Outsourcing Solar Roofs

GM's new outsourced solar roof

Based on much of what I've read and heard lately about renewable energy sources, I am becoming much more positive about Solar. While it's very small right now, Solar power is one of the few renewables that can scale to meet a large proportion of our energy needs. It is one of the few area that I can envision technology getting better and less expensive over time, unlike the physical limitations of biomass derived energy.

The major barriers for many residential and commercial buildings to place solar on their sun drenched roofs is the upfront costs. People and businesses have budgets for buying the electricity they need, but rarely do they have the resources to make a large upfront investment in something that will take years or decades to pay back. Creative financing and outsourcing to specialized firms is the answer. That's what GM decided to do:

Since June, the roof of G.M.'s parts warehouse in Cucamonga, Calif., has been host to a photovoltaic array with the ability to generate as much as 1.5 million kilowatt hours of electricity a year. The installation, which G.M. expects will provide half of the building's electricity, cost G.M. nothing.

A solar developer called Developing Energy Efficient Roof Systems -- commonly called Deers -- bought the equipment with money it raised from private financiers. Deers and its investors own the cells; G.M. signed a long-term contract to purchase the solar-generated electricity from them, at a discount to the prevailing rate for electricity in the region.

But this is not just using the current economics to make the deals work, there is an eye to the future where energy costs are expected to increase:

Companies must also persuade their own managements -- or in the case of leased buildings, their landlords -- to allow the installations. And, of course, the economics only make sense to people who think that prices for conventional energy will keep rising.

"We have an incentive to make sure the systems work well, because that's how we make our money," said Jigar Shah, who founded SunEdison in 2003 and is generally thought to have pioneered the solar services model. "But let's face it, we are putting a hole in their roof, so they have to trust we can do it properly. And if you think electricity rates will go down, these long-term contracts don't look good."

and carbon might be taxed and carbon credits traded:

Other factors are involved as well. The parties generally negotiate who will retain potential credits for reducing carbon emissions. When the developers and their backers keep the carbon abatement credits, they generally plan to sell them to companies that might otherwise have trouble complying with rules planned in California and expected elsewhere aimed at limiting global warming.

The electricity users could do that, too, but some of them might also use the credits to offset emissions from other parts of their operations.

But the same logic underpins all of the deals: The electricity users get a clean, reliable source of energy. The developers and their backers get an equally reliable return on their investment -- which can be as high as $6,000 per kilowatt hour of capacity -- as well as the tax credits and rebates that California and other states offer for renewable energy projects.

Which means that some of this is speculative, but if they are right that energy prices will continue to rise and carbon will become a taxed or traded commodity, they have a long term asset that will deliver positive cash flow and a cleaner environmental image.

As a result many other businesses are getting interested in this roof outsourcing concept as a no upfront cost, zero-risk way to put solar on their roofs.

"The energy is clean, and the fixed-price agreement doesn't fluctuate," Ms. McDonnell of Whole Foods said. "Seeing whether solar would work is now on our check list for every one of our new stores."

This is the model that NYC should embrace for creating more solar roofs. Stimulate local businesses to provide the engineering and financial know-how to building owners interested in allowing solar on their roofs in exchange for long term rooftop leases and fixed electrical prices.


I've been looking at the Mall and Warehouse rooftops around here thinking about exactly this plan.  I'm glad it's started!

As a landlord, I've looked into Solar Hot Water, and hope to get it soon, but have been wondering about a tax implication.  In Maine, we do have a rebate program for SDHW, but if I was installing a system for our one, and the two additional apartments, wouldn't I also be eligible for a 66% business expense deduction or amortization on the equipment?  A tax preparer was sceptical, but how could this not be a valid business expense?


I'd think of it more as a capital investment than an expense. Usually expenses are for little things that you use up, and capital is something that is amortized over several years...
Understood, but the question remains.  Whether it is expensed or amortised, is this something that could help encourage Landlords to make the investment?  Here in the northeast, a lot of people buy what was once a One-family, and is now a 'resident-landlord income property'.. I'm trying to find any advantage I can to convince both my wife and my neighbors that we need to be fitting out homes with this kind of heating system backup.  

Does a big tax writeoff in the form of a 5 or 10 year (??) amortized property count on top of the standard (In this case, Maine) State and Federal rebates, incentives?

Otherwise, it's a lot rougher to get moving on a $10-30K investment.

Anybody out there know the tax ins/outs about this?


One way to deal with some of these issues is to live in the property for a year.
Federal Tax Credits
and Accelerated Depreciation


Residential Solar Electric Systems:

Federal Income Tax Credit - 30% of the Total Installed System Cost. ($2000.00 cap)

California Energy Rebate is currently $2.60 per watt. Jan 1, 2007 the Ca Solar Initiative takes effect, giving the PUC control over all rebates with a starting rate of $2.50 per watt. This will be funded by all utility users and will be reduced about 10% each year until 2017.

CEC and PUC Rebates are considered taxable income by the IRS but not by California.
Newly constructed active solar systems are exempt from California Property Taxes.

Solar water heating, except for pools and spas, is eligible for a separate 30% Federal Tax Credit. ($2000.00 cap)
Download the Seia Tax Manual for more information.


Commercial Photovoltaic Systems:

Federal Investment Tax Credit - 30% of the Total Installed System Cost. (CEC and PUC rebates are considered taxable income by the IRS but not by California)

California Energy Commission Rebate is currently $2.60 per rated watt for systems up to 30kW. For larger systems the PUC rebate is now $2.50 per watt.

Accelerated 5 year Depreciation on the Total Cost of the System less 1/2 of the Tax Credit.( or 85% of the System Cost)

Newly constructed active solar systems are exempt from California Property Taxes.
Download the Seia Tax Manual for more information. We strongly suggest you contact a tax professional to minimize your net system costs.

Thanks, Wharf Rat!
   That makes sense to me.  I hope it makes sense to my accountant, who thought it was too much to ask to get depreciation on anything that had already gotten a Tax Credit.  But I keep thinking 'It is a business expense, right?' (or 2/3 of it, in our case)  It just seems that with alt energy, you get into a mentality that says 'this is different from other kinds of expenses, and doesn't count.'

So that means a $13k (estimate we got for sdhw, 3apt) installation is getting an immediate tax credit of  $3,900 , (leaving $9,100 ) and over 5yrs, 85%, or $11,050 x 2/3 = $7,359 gets amortised/depreciated.  Of course, there's a Maine SDHW rebate that comes off the front end, too, and I have to see if these can all work with each other.

I draw mice and build camera gear.. this stuff is a little alien to me.


I was just thinking that we need more posts on solar. I agree with you that it has real long-term staying power, and is in my opinion the only realistic shot we have at long-term PO mitigation.

I have seen some solar insolation maps, and if I recall correctly the Northeast had relatively low insolation compared to the rest of the country. Does anyone know if there is enough insolation there to make solar worthwhile? Are there any businesses or homeowners who have had success in use of solar?

  Actually, New England/Northeast has a pretty favorable insolation, compared with our neighbors around the great lakes and the Northwest.  

August  (NREL Map from 1961-1990 data)


We're about 1/3 below the Broiling Southwest, but don't show up much worse off than Atlanta or Houston.  Here on the Southern Maine coast, I think we're sunnier, but I don't have any maps that prove it.  Add to that, PV yields better current in colder air, and the North gets another little shot in the arm.

Bob Fiske

As someone just reminded me by e-mail, Germany has even less solar insolation than the Northeast states, and they have made solar work in a big way. I should have remembered that since I lived in Germany for 2 years.

I was sent a map showing Germany and U.S. side by side, but it is too small to make out details. If I can get the original source, I will post it.

Yes, the Germans know a good deal when they see one.

Even in overcast conditions, those panels are 'makin money'.. (if your electronics are smart enought to use it).. and I fully suspect that the panels that live in cloudier towns will be up there that much longer, too.

I was in Westphalia as an exchange student, 1983, and I don't really even remember much direct sunlight.  But every sunset was lovely, with the Sun as a distinct, Orange ball that looked like it was painted onto the gray sky.

"All's for the best in this Best of all possible worlds, of which I might say Westphalia is the center"

 -Dr. Pangloss, Candide

..and while I have the libretto in hand..  (OT alert..!)
(Our men are brave. The war is over, but we still have six divisions of artillery ready to start another war. It's been a long and bloody war, but if men didn't fight they would never know the benefits of peace, and if they didn't know the benefits of peace they would never know the benefits of war. You see, it all works out for the best.)

Only 4 weeks ago the largest installation of solar panels in Germany was opened near Munich, serving 700 households with 2.2 megawatts. (Link to german spoken page).
I still do not get 'solar'.  I guess after the land mass that is the continental USA has been moved southward, and the planet's rotation stopped with the aforesaid land mass direcly under the sun, it would be perfect, but hey until then...
Well, You might not get it until you've got it.. or till you really needed it.  But I've got some of them, and wouldn't trade that security for much of anything.  Mine aren't even up on the roof yet, but I know I can have power a few minutes after the grid fails, were it to do so, and could be getting juice for years to come from those panels, with little or no maintenance, and just a couple of branches and ropes to balance them on, if need-be.  The payback isn't even really an issue for me, tho' I can get my money back with them pretty easily, generating for myself, renting them, and could resell, likely at a profit, as well.  But people pay a very wide range of prices for electricity already, particularly for the convenience of 'remote power'..  if you saw the KWH price for your AA batts or for a Laptop battery, Cell phone, flashlight, WalkieTalkies, that .08/kwh would be balanced out with a much broader reality of what we shell out for electricity.  The weather and the chaos of the world energy relationships could bring that reality home to us very quickly.

Talk about the perfect being the enemy of the 'Really, very good'..  even on the equator, PV is not ever perfect, and it's not cheap.  It's just a good way of getting some watts.  No moving parts, long lifespan, not 'terribly' complicated.  You can just connect a panel to a couple batteries with paperclips, if that's all you've got, and it will charge, assuming they are somewhat matched up.  

Best to you,

'He's so contrary, if I heard he fell into the river, I'd look for the body upstream'

If there was a 'perfect' replacement, there wouldn't be much to discuss here, now would there?
Hello ImSceptical,

I have a 2.28 kw grid tie system in Southern Maine. After all the State and Federal rebates the system cost around $12,000. My theoretical payback was around 24 years. I will update the estimmate after I have a year's data. This is not a good return but I believe electricity rates are going to go up sharply making it look good in the future. And I'd rather spend my money on this than on a fancy car. The downside with a grid tie system is you don't have backup when the power goes out. To prevent islanding the systems are required to go off line in a blackout. But adding batteries and additional electronics to the system for backup really kills the economics. Plus you have to replace the batteries every 5+ years. It is expensive ($2k) and a hassle because the batteries my installer uses weigh 150 pounds each. I asked my installer about the NiMh batteries new for commercial backup. He believes these will be available for home use within 3 years and cost about $5k for a home sized bank plus a new $3k inverter / charger. Very expensive when you think about it but they would last a very long time. If the electric grid becomes as unreliable as some are predicting the cost may be worth the insurance. Hope this helps.

The equatorial regions of the planet are often cloudy and not very good for solar use. The US has some of the prime solar real estate in this world.

I think your thinking about solar is mostly clouded by a failure to inform yourself about the facts. There is no easier way to keep oneself in the dark than to believe in ones own "imachinations" rather than reading a good textbook on the subject.


There is probably no "one" solution to Peak Oil. There are probably at least 4 components to any solution: 1) conservation, 2) wind power, 3) solar power, 4) biomass, 5) nuclear etc.

It is probably a good idea to be open to all possibilities and evaluate each one on its merits.

Conversation really covers way too many concepts -
*smaller/more fuel efficient/human powered personal transportation
*less leisure transportation
*more efficient appliances
*change of behavior towards use of appliances
*rise of mass transportation
*change in building practices (eg, superinsulation)
*change in zoning practices (eg New Urbanism, mixed use, higher density)
*Reduction and elimination of population growth
*the rise of home gardening in the suburbs
*A population shift away from hostile environments
*Business getting smart about easy convervation measures, (eg excessive lighting, 24/7 computers, 24/7 AC)

Very little of this is achievable by fiat - there has to be high energy prices pulling people towards it as well.

The death of meat as a staple food.
More efficient community-based utilities like hot water where feasable.
Thermally adaptive building and HVAC processes (eg thermal-mass incorporation, waste heat capitalization, solar water heating, windcatchers)
More local food.
Sorry, but meat isn't a 'staple food' nowadays, at least when compared to our evolutionary ancestors, who ate at least twice as much meat as we do and no grains.

This is basic 'paleo diet' stuff. Google Loren Cordain, paleo diet. Amongst the other readings, look for an article titled 'Cereal Grains: Humanity's double-edged sword.'

Any planet where people eat grains and not meat (i.e. the current one) is a planet that people were not meant to live on.

The tiger does not live in a cage, and the human being does not live on bread, at all. That is nature, and all else is a perversion.

Yes, one can live a perverted life ... but that is another question entirely.

You may justify abstention from meat on 'moral' grounds, but not on natural (evolutionary) grounds. To abstain from meat is therefore the ultimate moral choice...


Takes up 3 of the 5 bars at the top of the Paleo Diet site.

I never suggested that one abstain from meat on natural grounds - I find it curious that you would read that into my post.  I suggested that reducing the 'it isn't actually a meal[just a side dish!] without some form of beef, pork, or chicken' belief that pervades American culture is a key form of conservation.  In an agriculture crunch, it's not going to be quite so justifiable to spend 9000 calories of highly-subsidized corn on 1000 calories of beef.  Which is what we currently do with 80% of our grain harvest.  Meat is a necessary part of our diet, but not in the portions consumed now - look at Eastern diets.  A fat upper class Bangladeshi eats an order of magnitude less meat.

I don't do morality on the PETA level - they can't present a substantive moral framework, it's all particularly photogenic objections and slippery slopes (so was that bug I just squashed a crime?  I know that baby seal being clubbed was bad, but think of the fish you just saved!).  I'll eat my steaks for as long as they're affordable, my point is that they won't be.

  Hey got some good photos and interview with my neighbor....

The Silicon in PV panels, how do they mine/produce it and what is the process? Also is this (in your opinion) going to be outclassed in a few years by nanosolar? Also everyone talks about stirling engines and concentrators etc, where are they and if they are so good why is nobody selling them?


Hey got some good photos and interview with my neighbor....

I am anxious to hear the details. Were you convinced?

On your questions, I just don't know. My old research advisor at Texas A&M, Mark Holtzapple, was always working on Stirling engines. I think he has tried to sell some of his prototypes, but I don't know if he has had success.

Everyone talks about stirling engines and concentrators etc, where are they and if they are so good why is nobody selling them?

Let's restrict ourselves to Stirlings.

And the correct question is: why are they (the masses) not buying them?
Plenty of sellers are out there trying to "sell". (Wow, learned something myself tonight ... that the rhombic guys closed shop.)

Step back and imagine yourself as a drop of gasoline.
You know how you got here, from oil well through refining, trucked to the gas station, pumped into tank of a car, etc.

Now you are sitting in the fuel injector, about to get squirted into the combustion chamber of an ICE engine. All your energy is still there, the teeming chemical bonds between your carbon and hydrogen atoms being fused into the lowest energy state they could find; ... until now.


You're in. Getting squished. Introduced to a new friend: oxygen atoms. They look so nice and friendly. Ignition. You break yourself up to mate with your new friend. In the frenzy of mating, all this energy is released: heat, pressure are released ... you find yourself pushing against a compliant piston.


You're out. Still burning hot. Still full of high pressure. The piston took out only a small part (30%) of your energy as payment in kinetic form. Then the exhaust valve popped open. Now you feel different. You feel used and dirty. It all happened in a split of a second. You are now a cloud of carbon dioxide atoms, and a few more noxious compunds, spreading thin into the atomosphere, diffusing, disappearing. Your energy is entropizing itself out into the ambient.

You feel oh so "used".

It happened too fast. "They" rapidly sucked a small portion (30%) of your energy ... and then threw you out. How inefficient, but yet how super fast. Behind you was another drop, and then another. Boom. Boom. Boom.

Enormous amounts of energy were released rapidly. All so some car can go Zoom Zoom Zoom.

The owner of that car enjoyed the "rush", the surge of fast "power". That's why he bought you. He enjoyed the adrenalin rush. He "valued" it. He paid "money" for the rush.

Had you been a drop of working fluid in a Stirling, they would have kept you circling back and forth, well, almost forever. But the speed of cycling will be so agonizingly slow as heat energy has to diffuse into your body and later seep out. Your human "owner" is unhappy. No more Zoom Zoom Zoom. The energy now comes as drip, drip, drip. Efficient, but slooooooow. He does not "value" slow. How boring. So he does not buy.

So the sellers sit and wait.
One day. One day, they think. The buyers will develop a new "values" system; when the zoom zoom drug is gone.

Eh?  Did somebody mumble Stirling engine?  Gotta wake up and reel off my standard comments.
Just between you and me, here is the straight skinny re stirling and money people

Q- Have they been around a long time with no commercialization?
A -Yes.
C- Very, Very Bad.

Q- Has somebody invested a lot of money trying to commercialize- and failed?
A- Yes.
C- Very, Very, Very Bad!  Us money guys don't want none of that kind of opportunity.  G'by.

My comment-  Very myopic attitude.  Sure, stirlings have been around for close to 200 years.  So has a whole bunch of stuff been around a long time with no commercialization- think of thermoelectrics, fuel cells.  What you have to answer is WHY- and are things different now than then?

The answer is obviously yes, very different, like $60/barrel rather than $ 16/barrel.

Then another one that seems to completely escape people since it is slightly technical.  There are two kinds of stirling engine- crank types, that take lubrication, and free piston types that slide on a gas film and/or an aligning spring that don't take lubrication.  Crank stirlings don't have long life, and free pistons do.  That simple.  Don't believe me?  Look it up yourself.  Dean Kamen knew about both,  made the wrong choice, spent a lot of money, and had to quit, and now must be feeling like a fool.

It happens that right now, the only free pistons are little things used by NASA, but that is a mere accident of history.  Free pistons can be made as big as anybody would want- like biomss fired tractor engines, one of my favorites.

Other near term applications that the money people ought to be excited about;
domestic cogen.  Why burn gas at 85% availability  and get only heat?  A thermodynamic atrocity!  Get your house electric power as well.
Solar!  Look at that big hot spot in the south west.  Stick a bunch of stirlings there- way cheaper than PV.  (sad to say, the SES people are using cranks, and they crap out.  How utterly predictable- and utterly stupid!)
Heat driven heat pumps.  Lots of clever ways to use stirlings to do that, with excellent overall efficiency.
And many more.

OK, did my chore.  Goin' back to bed.

to wimbi,


The CHP (Combined Heat and Power) industry may be one of the most under-funded, undertalked about new growth industries in the world, and soon.

It is already well underway, and is getting the "money people" to take notice.

It mixes well with the ideas fo distributed generation, energy security, flexibility, renewables, and de-regulation.

For a great starting place go to

Look at the FREE back issues, and then register for their FREE print magazine.  It is EXCELLENT, with a great open mind to wind, solar, Diesel, nat gas, propane and Stirling methods of co-gen CHP.

It was an eye opener to me how far things are already developing.

Roger Conner  known to you as ThatsItImout

Good reference.  It quotes a Japanese CHP based on an IC engine that needs an overhaul at 40,000 hrs.  That's excellent for an IC engine, but actually mediocre for a free piston stirling, some of which have near 100,000hrs on them.  And they are almost noiseless, not just quiet.  Also, stirling CHP in a restaurant could be eating garbage, and not be needing refined fuel.

I am looking forward to another run of my 1kW free piston tomorrow.  The first runs were ok but we found some silly tuning errors of the kind I should have caught but didn't, and got about 500 watts.  Oh Boy, next run should be great!

This one is for my wood stove.  My house uses about 350 watts electric, steady state.

"It is one of the few area that I can envision technology getting better and less expensive over time, unlike the physical limitations of biomass derived energy."

Good point. With bio fuels, the first steps are the cheapest, as cheap excess capacity is used up (as in used french fry oil that is discarded now). But with scaling, the costs rise as you compete with foodstuffs for energy.

Similiarly, as demand rises for coal, the railroads are overtaxed, excess capacity disappears and prices rise.

But with solar, economies of scale can drive prices down, at least theoretically. Right now, unfortunately, the worldwide shortage of silicon is making PV cells much harder to find. And some of the alternatives to conventional silicon use rare heavy metals which could become bottlenecks.

Let us hope that some of these new PV technologies prove to be both viable and scalable.

With bio fuels, the first steps are the cheapest, as cheap excess capacity is used up (as in used french fry oil that is discarded now). But with scaling, the costs rise as you compete with foodstuffs for energy.


And you are right about the bottlenecks. Does anyone have any ideas on how that situation will play out?

Here is what I am talking about:

Most of the Northeast is in the 3,000-4,000 Watt/hrs per square meter range. West of the Mississippi the average looks to be 5,000 or more. I don't know what is required for viability. I suspect that since the Mars rovers are using solar cells to charge their batteries, even the most overcast areas of the country could produce solar energy. But you will get more bang for the buck in Arizona, New Mexico, and Southern California.

Damn clouds!

Thanks for the map RR. That sure is a nice sweet spot down in Southern California, Arizona and New Mexico.

The other thing is that the region is sparsely inhabited. A lot of it is desert. You could put a lot of solar plants out in that region.
And it doesn't have much water to spare for biomass crops.

And they probably get peak load around the same times that insolation is highest too.

Solar could be the saving grace of the dry southwest.

We live in the dark red area in southern Arizona, and solar works quite well. I'm surprised to see just how little insolation there is in the north east.

by the way, the PV ratings are misleading. The current coming off the PV is 17 volt, but the batteries can't take more than 14.1 or so; if you use a MPPT (maximum power point tracker?) controller you can translate some of that voltage to current, but you lose some of it. Plus, the batteries lose a percentage both charging and discharging.

Just something to keep in mind... I still wouldnt' trade it for a power line, even if it was free. I like being independent.

 Maybe you meant to say you have a 17 volt module and the batteries are rated at 14.1?  The amount of current that the module puts out will simply determine how fast you charge the batteries.  I guess the point you were trying to make is that any voltage over the handling capacity of the batteries is essentially wasted in the sense that it is converted to heat.  Which is a valid point.  However, all the current us used.  The more the merrier!  I guess the other point you were trying to make is that the efficiency of the solar pannels is a misleading term and here we agree completely.

The efficiency is generally defined as the power out divided by the incident power. In essence what fraction of the incident power is converted to electricity.  However, that value is for a standard spectrum (no clouds, bright sunny day) and at a constant temperature (usually 25°C).  

And, as you imply, if you want to know how much electricity you can expect to get out of your system, you also need to know the efficiency of all the other components, the batteries or other storage device, plus the inverter.  All of this is why the efficiency of the cells matter.

The efficiency also assumes that the panel is running at its optimal voltage.

You can run the output of a 17-volt PV panel into a 14.1 volt battery, but you'll get less than the rated power that way; P=I*V, and the current increases very little compared to the cut in voltage.  That's what power-point trackers do:  they take the extra energy from that voltage drop and use it to increase the total current into the batteries.

OK, sorry to be a spoil sport, but I have to bring up a subject that worries me concerning solar panels.  Theft.  I'm sure you've thought about this, Jim, since you're off the grid.  If we do go through a rough chaotic period up ahead, I'd think one of the first things people might want to steal would be solar panels.  
The desert southwest is ripe for solar thermal.  In areas with reliable sunlight they can produce a lot of power during the day while storing some for the night in thermal mass (such as molten salt).  NM, AZ, and NV have great potential to produce and export electricity.
I was involved with the development of Luz solar thermal power plants in the Mojave desert in the late 1980's and I can recall that it was far more important to provide electricity and capacity during the summer peak hours, which fortunately are when the insolation is at its highest.  

"Saving" the heat for later in the day was not given much or any consideration in designing the plants.  Rather, the plants used allowable natural gas input (25% of total energy input) to supplement solar input during the peak periods and thus maximize "Capacity Payments" by the utility.

I was also involved with a couple of the Luz plants.  I remember it was the Standard Offer 4(?) that gave investors a 10 day guarentede rate, and then after that it was avoided  cost of electricity, which was natural gas, the bubble which was expected to burst by 1992 at the latest.  The peak production for AC/office load had it seem such an excellent investment.  Tsk, tsk...    At least it wasn't my money.....
The California Standard Offer 4 contracts gave a 10 YEAR period of price protection, with what turned out to be attractive rates.

Luz also developed two 80 Megawatt solar thermal projects under standard offer 2 contracts which had no such protections.  When Luz's inventory of contracts run out in 1990, the company dissolved.

Great, 'kill more life' seems to be America's motto.  Depriving the local flora and fauna of sunlight would destroy whatever life there is in the desert, and it's not neglible in the US southwast!
Do you live in a house on planet Earth? If so, how is the local flora and fauna faring underneath your house?
Actually, PV panels aren't necessarily bad for the environment here in Arizona. If there is some shade, there is less evaporation and more plants can grow. Animals like the shade, and you'll find quite a bit more biodiversity there.

The issue is cost per square meter. When I drive across the scrub brush covered plains, I try to picture them covered with PV panels, and it boggles the mind. Even if the price dropped by an order of magnitude, getting enough power for Americans' insatiable power desires would bankrupt the global economy.

I kind of think the answer is covering structures with PVs, paired with conservation.  

" I try to picture them covered with PV panels, and it boggles the mind."

"At present levels of efficiency,  it would take about 10,000 square miles of solar panels-an area bigger than Vermont- to satisfy all the United States' electricity needs. But the land requirement sounds much more daunting than it is. Open country wouldn't have to be covered. All those panels could fit on less than a quarter of the roofs and pavement space in cities and suburbs."

National Geographic, Aug, 2005


My father-in-law lives in Phoenix, and I'm just stunned to see how few rooftops are adorned.  Ok, stunned, but not surprised, if I may say so.

As I said above, New England 'isn't all that bad' as far as solar goes, and does have the added benefit of getting better performance from the panels it does use, due to the cooler conditions, which lowers the resistance in the PV (all) circuitry, I believe.  Panels on Arizonan rooftops could also keep the homes more shaded, which could also help reduce demand.  There are some systems which cool the PV panels with  a coolant liquid, which is then transferred to preheating the Domestic Hot water supply, benefitting the user in 2 or 3 ways at once! (If you're counting the shade-benefit)

Bob Fiske

Yeah, you noticed that too, huh? :-)

Right behind LA, San Fran and the largest concentration of electric consumption luxury lovers in the world!  What a market for solar!  And what a chunk of electric power (and with plug hybrid technology, transportation fuel the solar techies are getting ready to pick off...and what a relief on the fuel strain right there....it's getting ready to get interesting....does anyone wonder why the Saudi's keep grumbling about this "green energy" craze that seems to be taking hold....as the military officer in the movie said "we got to get a handle on this or this peace bug could really start to catch on!"

Roger Conner  known to you as ThatsItImout

There's a nice red spot in the Hawaiian islands, too. It seems a bit odd that the weather would vary much from one island to another, but I'd guess that it does vary quite a bit with altitude ...
It varies with which side of the island you are on. Most of the islands have rather large volcanoes in the center, which drain the tradewinds of moisture. So one side will be very wet, the other dry.
A while back I saw some maps showing average wind power, and to some degree and in some areas it appeared to be almost an inverse of the insolation map you presented.  The Northeast coastal areas, Great Lakes region, and parts of the Pacific Northwest have quite good average wind power.

This further reinforces my belief that solar and wind power are complimentary and can be beneficially integrated into a combined system. Cloudy wintery days along the New England coast might not generate much solar power, but would really have those wind turbines spinning to the max. Conversely, summer days in the Southwest might not be too windy but would really have solar collectors cooking.  I suspect that the area of maximum combined average solar + wind power lies somewhere in the central plains, perhaps in Kansas, Oklahoma, or Texas panhandle.  

It shouldn't be too difficult to optimize a combined system for the proper ratio of solar to wind power. One goal would be to damp out some of the more severe peaks and valleys, particularly those that can last quite a while and play havoc with energy supply, e.g., a week of overcast weather, or those breeze-less summer doldrums.

Good point. Here in Ariz, I had thought of getting a Bowjon/Windlift windmill for pumping water; but after seeing the wind map I gave up, and am counting solely on solar. The windmap goes from 0 to 10, and we're 0! Conversely, the sun shines 300 days a year, and the moonshine is more or less constant ;-)
Just curious since you brought it up.  How effective are solar cells in picking up Moonlight for energy generation?
Moonlight supplies no appreciable energy. It is a tribute to our sensory perceptive abilities that we are able to see and function in both sunlight and moonlight. Sunlight is approximately 5 million times brighter than full moonlight.
So we can't run an Oil CEO off moonshine?  I think he operates better sans sunshine.

joule said,
"This further reinforces my belief that solar and wind power are complimentary and can be beneficially integrated into a combined system."

golly damm, now we are startin' to GET IT!  It's the confluence, folks, that will overcome most of these little grumbles you keep hearing ("gee, what if the wind don't blow....gee, what if the sun don't shine...", golly gee shiit, what a bunch of whiners...they never ask, gee, what if Saudi buffoons go nuts and blow up the oil production facilities...compare that to the likelyhood of the sun not shinin'...idiots).

Now, let's talk a bit of a really pretty confluence here...take the solar map, take the windmap, take the brownbelt areas around every formerly industrial city large and small, take the sewer gas and the landfills and the agricultural factory farms and processsing plants...mix 1/3 wind, 1/3 sun, and 1/3 renewable methane from waste product and sewer gas...gee, does that start to fill in the "variability" problem a bit....huh, does, it huh, huh?

O.K., fine, your still a bit nervous...o.k.....go down the Ohio and Mississippi River and spot out some good valleys....now, about 12 to 24 manmade lakes, with pumped hydro storage using the wind and solar....and of course, we still have the remaining nukes throughout the region, so instead of building any new ones, we modernize and add units to the ones where they are, since, well, no one exactly seems running scared of the ones already there, but they sure as hell don't want a new one in a suburb full of folks that has NEVER even seen one up close...is it startin' to sound like a plan, huh, is it?

So... up to our azz in renewable, storable energy, and methods to have the single most stable grid and comfortable old farts on the planet...did I miss anything....oh yeah, the small scale distributed generation that will stabalize the grid and make it almost terrorist, storm, natural disaster, and supply interruption proof (with some large propane and methane tanks well scattered throughout the system, all built over that great stable base....distributed power, stability, diversity, and price and market leverage....a case hardened energy system to last the next century...just what I have been pushing from my first days forking this line on TOD and lovin' every minute of it, and now, folks are starting to GET IT!  :-)

OPPS, something has to be lacking, it cannot be this good, this easy, where is the fly in the ointment?

Well, there is one problem, sadly.  It's not that it won't work technically, or that it is financially undoable (helll, we could have done the whole thing for half the cost of the Gulf War or the Ray Gun defense buildup, and gotten far more in return, and been more powerful than the above would have made us), no, the problem is this:  since about 1970 to 1980, we decided that them there egghead intellectuals and technicians were gay weirdos and sure didn't want our brats to be one of them lefty leaning enviro book readin' types....so we didn't bother with the ole' edukashoon system much...in fact, we perty much decided them book learnins is what caused that whole campus radical thing, and that peacenik bug and that global warming crap....and now they talk about peek oil or something like that, and them peekers, who did seem to understand the problem, got so down they decided it was a waste to send juinor to college, better to teach him how to plow with a mule, or harvest turnip greens, or develop a taste for grasshoppers,  or some such shiit....so, here's the problem...


Noooo, we decided to teach him to live off the land, like Hank Juinor or something, instead of being a dammed bidness man.....

SO NOW TO BUILD THE ENERGY SYSTEM THAT ONLY AMERICAN CONDITIONS CAN PROVIDE, AND DOES NEED, WE WILL HAVE TO GIVE THE MONEY TO A BUNCH OF IMPORT CHINESE AND INDIAN TECHNICIANS....who by the way, will be livin' large in the best neighborhoods and shackin' the upmarket girls....while your boomer doomer son is doing what....smokin' dope in a log cabin by a wood stove, chuckin down beans and turnip greens, waitin' for the crash...

yeah, well, for him the crash is already here...


Roger Conner  known to you as ThatsItImout

(p.s.  I have had a very hard week....you will never know how much fun writing that was for me! :-)

ThatsItImout -

"(p.s.  I have had a very hard week....you will never know how much fun writing that was for me! :-)"

Gee, I never would have guessed!  You should really try to put more feeling into your writing. :-)

One one point I'd have to disagree with you a bit. There is plenty of technical expertise right here in the good 'ol US of A; it's just that much of it is underutilized.  Look how many experienced and talented engineers and scientists are engaged in either non-technical or marginally technical jobs because of corporate cut-backs and outsourcing. The limiting thing to implementing some of these alternative energy schemes we've both talked about is the unwillingness and/or inability to mobilize the huge amounts of capital required.

Having said that, I would still have to agree that the public education system in the US is abysmal, and that higher education, to a large extent,  has become a very expensive racket.  

40% of engineers and scientists are immigrants. The US system has a long history of piggybacking in top of other country's educational systems.

One could also say it otherwise: the US cheats a lot of its young people out of an education....

Downright Poetic, Roger!


During the runup to Y2K I consulted for a very large state electric utility corporation. It had been recently absorbed by another utility and I was shocked at what then transpired.

They almost immediately starting shedding all the EE's(electrical engineers). Their statement appeared to be"if someone wants something different in their power arrangement then they can either take what we have already or go elsewhere".

IOW they didn't need any damn inovation.

This was corporate philosophy as to making the quick buck and screw the rest of Amurkah and what they might need.

Guess what? The are still doing it. Engineers and programmers bit the dust long time back. In fact between Y2K and now and its still happening.

All to increase the 'bottom line' so the execs and CEOs can run to the bank laughing as they merrily go while we get to eat ashcakes.

Hey its the AhMurican Dream , non mon ami?

If industry(what industry?) doesn't hire then you certainly do not train or educate and industry(what industry) certainly isn't hiring.

Couple days back a truck mechanic  said to me" boy we can't hire any good mechanics". Funny thing. That was just bullshit. They don't even put out ads. They don't WANT to hire any except the lowest paid mech thats willing to work for almost nothing.

Folks its all the front office(ivory tower boyz) who are putting us here. I don't see Bush behind it. I dont' see red states behind it. I see corporate ASSHOLES behind it.

I say tax the fokkers to hell and back. Let them eat 1040 IRS forms. Find their little offshored havens and make them pay. Put the rest in jail like Skilling is. Hang whats left.

According to today's NY Times they are trying their best to put themselves beyond the law.

airdale said,
"Couple days back a truck mechanic  said to me" boy we can't hire any good mechanics"."

Several years ago, when I was in the auto service trade, I put in for a job at Volkswagen dealership, at the request of the shop foreman.  I got no replies, so I talked to him on the side, since I knew him personally, asking if there was anything wrong with my application.

"No", he said, "they decided they are not going to hire anybody", even though the foreman had  told the owner/operator of the dealership they needed people badly, because customers were being made to wait long periods for service.  The owner had told him, per his accounting of the conversation, "So?  Let them wait, where in the helll else they gonna' go?"

On a small scale, that about sums it up, don't it?  (by the way, I am no longer in the auto service trade.)

Roger Conner  known to you as ThatsItImout

I do(did) some computer work for a local auto dealership which was both a Chrysler and a GM(Chevrolet) Dealer.

So the lineup was Chrysler,Dodge,Jeep, Chevrolet in its variants(pickups,vans,suvs,etc).

I spent 5 ,12 hr days installing the Star Mobile scan tool for them. The latest CAN(Controller Area Network) vehicles(2004 and up) for Daimler/Chrysler lineup no longer use the DRBIII tool but must use the Star Scan or Star Mobile.Most I suspect use the Star Scan with an ethernet connection to the Tech Station(desktop).

I had to install an AP(access point),additional router and a switch plus put on all the upgrades for the tool.

There were a lot of bugs but I got it going and it was fantastic in operation. The servive mgr could sit as he desktop in his office,have someone else plug the Star Mobile into the OBD-II connector,even it the vehicle was in the parking lot. He could look at the whole network of modules(about 40 of them) in the vehicle and query each one plus active every actuator in the vehicle. Like accelerate the engine,turn various lights on and off and just about everything but drive the car remotely.

Now its obvious that a mechanic can walk up to a customers vehicle , open the hood and look at it and not be able to diagnose a damn thing. He can just stare at it and thats about all. If a shadetree mechanic is so stupid as to try to repair a vehicle with full electronic modules he will certainly destroy it. So the service mgr and then check the DTC,put up graphs, like to chart the O2 sensors vs rpm and so on. He then discovers the problems(usually via the store DTCs) and then yells at the mechanic as to what to repair or replace.

This is extreme high tech. Not only that he can have the tool go online to the manufacturer, download EVERY flash for the VIN , send them over the wireless AP, have the Star Mobile install each and every one with full checkpointing and with no failure possible due to caching the flashs and installing but not applying until the full flash is at the module. In other words Fail Safe.

Yes very high tech and most all mechs are not aware of the technology available to them nor how to really use it. The vehicles are way way way beyond their capabilities.

Now the end of the story. The week after I did all this work the dealship dropped the D/Chrysler line. Pulled one of the shops Tech Stations,shipped out all the parts.

I decided on my next visit to DROP the account. I realized that the front office were a pack of fools. I was not going to take any more calls from them nor schedule anymore hours there. Let them fight the technology I put in place on the rest of the network. Last time I was there some idiot was pulling desks out and slashing thru all the nework wiring. Even knocking the server desktop around. I just picked up my briefcase of tools and walked out.

This is the way it goes. No need fighting it. If I ever return it will be only for a threefold increase in my bill rate. I don't have to charge a measly $30/hr bill rate for such idioticy. I prefer to not just take the calls and I likely won't.

I surveyed the rest of the region as to their install of the same tools. I drew blank stares speaking to the service mgrs at the other dealerships.

Its no wonder we are in deep kaka in this country.

You want to read out your DTCs? Oh..thats $56 or more at a dealer for a 5 minute job. You want a SKIM key(ignition) key? Thats $48 plus $20 to cut the key(a 3 minute job). You want it programmed for the 'pin' code and this must be done)thats an additional $38.

Thing is that you can read your own major DTCs on chrysler products by simply switching the key on and off 3 times and it reads out via the speedometer LCD. They never tell customers this.

Again..why we are in deep kaka and circling the drain. Stupidity.


Here's another way of looking at NYC:

Every two days, more energy falls on New York State from the sun's rays than the total amount of energy consumed by the state all year (Perez, 2002). Each square foot of New York City receives the equivalent of 160 kWh of sunlight per year. This solar energy could be converted into over 125 thousand gigawatt-hours of electricity, or more than 2.5 times the city's 2005 demand (Perez, 2001).  

The challenge for New York City is therefore not whether there is enough sunlight to power the city, but how to best capture and use the city's solar energy resource.

According to recent estimates, there is enough commercial and residential roof space to host between 8,500 MW and 15,700 MW of photovoltaic (PV) installations within the New York City area (Chaudhari et al., 2005; Plunkett et al., 2003b). If the correct policy incentives were put in place and market barriers were removed, a recent report prepared for NYSERDA estimates that 7,736 MW of PV could be installed within New York City
by 2023

Source: CUNY (pdf)

And that's just within NYC!

Careful with those numbers. PV power is usually defined as PEAK units. In NYC you probably get less than one eight of the peak power on average. So 8.5GW peak make not much more than 1GW CONTINUOUS.

Are your numbers corrected for that?

In any case... PV are expensive and to use them in environments where they are utilized to 60%, at best, makes little sense. Put PV on roofs in the Southwest first. It is by far more sensible an idea than to cover the northern states.  

Here in Vermont my impression in the last few years is that the climate is changing towards less sunshine (and more rain), especially in May, June and October.  This year the growing season has been especially bad.  (Plants are solar panels too!)  Of course it is dangerous to extrapolate from a few years to the future climate, but this is consistent with the climate-change models.  Big worry here for both agriculture and PV.  Wind power seems like a better bet here.  And the famous "negawatts" (conservation).  And firewood of course, the Original Biofuel (tm).

BTW, cooler PV panels is of no help while they are covered with snow...

But they look pretty!  It could be our new 'Covered Bridge' look.  .. Now come on, those kids you pay to mow the yard in the summertime, don't they shovel in the winter, too?

During the Icestorm in '96(?), a guy we know in the Bethel area had his hot water panels working just hours after the storm, giving his neighbors showers, when many in Maine would have dark homes for weeks afterwards.

.. but who knows about the sun/cloud question.  I agree that with the 'winds of change', that a storm-tolerant turbine might be a really good part of the portfolio.  That's why I have been looking at those verticals I linked the other day.

This is a nice map! It clearly shows where food can be grown. Uh, the heartland is where the majority of food can be grown.
Now the definition of Heartland is another story!
Note to self, stay away from West Texas, New Mexico, Arizona, Nevada, most of Colorado and Utah as well as California for agricultural reasons!
Hey, Don't quit at the border!  Lots of good sun in Mexico, and could put lots of good Mexicans to work so they wouldn't have to cross that hot spot to get to jobs here.
I see that the panels are horizontal. Does that make sense?  Perhaps it is because the roof is horizontal.
At a recent demonstration, a solar installer showed me a chart that described the power falloff of PV when off-axis to the sun, and it was surprisingly lenient.

The sites I just found seemed to say that you lose .5% for every degree you go off-axis, but I think this is shorthand, since it is unlikely to be a linear progression.

I recall that the power drop when the panel was 15deg off-axis still left you with over 95% of your output.  Siting the panels as they have may have saved them as much structurally as using fewer panels standing to face the ideal azimuth.

One addition I haven't heard much about, which I'll be trying with mine is how much extra light a panel can accept without getting cooked, so that those flat-mounted panels could have a row of standing mirrors at their north end, giving them a boost up to some 1.25 to 2 suns of input.

Geometrically it is a cosine relationship, which means that the power drops off with roughly the square of the angle when measured relative to the optimum incidence. But again, that is mediated by the fact that solar cells do no only pick up the direct radiation from the sun but also diffuse radiation which makes up a lot of the total flux when averaged over a year in non-desert loacations. That is why fixed panel systems do not suffer a deadly penalty when compared to heliostats.

Mirror concentrators generally require some form of heliostat and very careful planning. They also loose most of the diffuse radiation. I don't think they are viable in any but desert environments.  

Even flat mirror concentrators only work well with special concentrating cells. Solar cells need a top electrode to collect the charge carriers from the PN-junction of the cell. This electrode is made out of a combination of transparent, low conductivity films and metalic meshes. The cell area under the metalic mesh is lost and the effective cell efficiency is limited by the non-transparent part of the electrode. These electrode materials have an ohmic resistance and there is an I2R loss when current is flowing through the cell. In a concentrator cell the geometric structure of the mesh and the quality of the transparent electrode are optimized so that I2R losses are much less than in a cell made for direct illumination.  

On top of these losses, concentration greatly increases cell temperature which means that the output voltage drops, again decreasing efficiency. Higher temperatures also mean reduced lifetime for these cells unless special measures to control cell temperature are being taken like air/water cooling and far IR reflective coatings (to minimize absorption of radiation that the cell can't convert anyway). Not to mention that there are secondary and tertiary reflections of surfaces which will illuminate cells inhomogeniously, another source of power loss AND potential destruction. Also, please keep in mind that unless you know what you are doing a concentrator system can easily set a house on fire...

There are many reasons why concentrators are less interesting for residential use than in power plants. I could only mention a few technical problems. I have, by the way, done a few experiments with commercial solar cells and 2-3 times concentration with flat mirrors. The results were dissapointing, at best. After a few seconds the temperature rise on the cell practically reduced the efficiency to such a low number that there was barely a net effect. And the temperatures were so high that the cell lifetime would have been measured in weeks, at best, not 25 years.

None of this holds for concentrating cells. But even then the gain in efficiency is offset by far by the complexity of a heliostat and the MUCH higher price for the currently available cells.

I'm fairly sure you arent aware of the state of the art in photovoltaic concentration. VMJ cells and thermophotovoltaics work efficiently at 1000 suns or more, and bandgap tuning is easy with dichroic filters.

And a heliostat is far less expensive than the silicon panels themselves. Oh sure, there are applications for flat panels, but the cheapest per amortized kw/hr will all be concentrator based.

Yes. I am aware. My post was restricted to what can be done on a rooftop with standard cells. Most of the ecologically non-invasive solar area we have is roof tops. I don't think the L.A. fire department will like hundreds of thousands of solar concentrators with 1000 suns and temperatures way beyond the flash point of tar paper and wood (in case of a failure) in the middle of the city.

I don't think there is much research in that direction, either. Most of the photovoltaics market is silicon panels and will stay silicon panels for the near future. I don't expect to see other than thin film technologies to pick up much of the capacity anytime soon. For now that is fine. By the time we have 30-40% efficiency, the old panels are ready to be replaced.

I might be wrong, though. I wouldn't mind a few GW comming from large plants. It would certainly raise awareness, if for no other reason than it's impressive scale.

I share the enthusiasm in the above posts.  When I posted this story on drumbeat a few days ago, I titled it "The future is now."  It seems that solar could play a huge role in allowing us to power down more gently.  But, isn't solar technology a bit of a peak technology?  Will it be possible to produce these panels 250 years from now?
I also find irony in the fact that it's powering the GM facility, which, in turn, helps keep our cars on the roads.
And, I love the Thomas Edison quote we always see "I'd put my money on solar energy...I hope we don't have to wait til oil and coal run out before we tackle that."
  1. I understand much of the material in a solar panel is recyclable, and there'll be some easy mining when all the landfills we've packed with 'cheap' electronics start looking more and more precious with all the various materials we've seen fit to discard.  There's a lot of Si out there in old tv's and answering machines (and Pentium 3's for that matter) that could be reprocessed and put up on the shingles.

  2. Let the wealth of GM buy a bunch of roofloads, and you be first in line at the fire sale.  Those panels will outlive the company; immortal corporate 'personhood' or not.  I want us to use what oil energy we can to be building up our 'next-generation-generation', so I see this as a step in the right direction.

The most common elements in Earth's crust are oxygen (46%) and silicon (28%). They are followed by aluminum (8%) and iron (5.6%). Together these elements are essentially enough to make the bulk of solar cells and their carriers.

We will never run out of solar cells until we manage to strip the planet down to its iron core.



There are lots of different varieties of PV technology.  Some are better suited to areas of low insolation and others are better suited to areas of high isolation.  Right now the market is dominated by a sort of plain vanilla flat plate silicon module.  It will probably stay that way for some time at the current rate of investment in advanced R&D.  But there are lots of promising alternatives, particularly for areas of high insolation.  And a changing investment environment may stimulate research and development in a number of already well defined paths that would lead to really spectacular performance levels.  As an aside there should be a NOVA special on concentrating photovoltaics airing sometime early next year.  They were out filming at NREL last month.
There has been a lot of excitment about the new thin-film CIGS (copper-indium-gallium-selenium) photocells. Gallium is extracted as a trace element from rocks mined for other reasons (e.g., bauxite). Gallium is the rarest component of the new photovoltaic cells (copper-indium-gallium-selenium). The total world gallium production is about 250 tons per year (compared to oil production of about 150 tons per second).  The cell phone and dotcom bubble craze drove the price of gallium to quintuple in 2001, leading to gallium recycling (from waste water, trimmings, cracked chips), but then the price dropped, causing huge layoffs in the gallium recycling business (AKA the genius of capitalism). The new-style photovoltaic plants currently under construction will use a substantial portion of the world's gallium supply. All current gallium extraction and recycling is fossil-fueled. It remains an empirical question whether the gallium usage of industrial civilization (and the silver, zinc, copper, palladium, gold, and other metal usage, all of which are recyclable to some extent) is truly sustainable over 100 or 1000 year periods. Probably no way to know until we succeed or fail.
The In is problematic as well.  The saving grace is in the "Thin-film" nature of the technology.  Absorber films are generally on the order of a couple of microns thick.  The Ga is a rather small fraction of the compound, I forget how much they need to add to straight CIS to raise the band-gap from its value at CIS with no Ga at about 0.95 eV to the common bandgap value of 1.15 eV which seems to give the best efficiency under the global spectrum, but it isn't much.  In however is another story.  No getting around the requirement there and it is rather expensive.  I think it is primarily a by-product of Al extraction.  And there is only so much of it.  The opto-electronic industry uses InP based materials for lasers and such.
There is no need to use either element in large quantities. Silicon does just fine for most applications. If we have a strong need for high efficiency solar cells, it is in concentrator applications where we have 400-1000 suns of concentration. The amounts of material needed for those are miniscule compared to rooftop arrays.

And please don't forget... one can tune the band structure of a semiconductor FAR BETTER by structuring the surface/bulk than by choosing different chemical elements. We will most likely see modified silicon/germanium cells far sooner than we will run out of trace elements. And the residential application sweetspot will probably be around 30-40% efficiency, anyway.

We still have the big issue of storing solar and wind energy for that matter. I think that this is the biggest stumbling block. The technologies for both could be underwritten today but until we get a good storage strategy we still don't have a solution. Pumped storage on the grid looks useful. Hydraulic storage looks interesting. Flywheels.

I of course like condensed gas storage.

Maybe super capacitors could work ?


At least we can  'Make hay while the sun shines.'..

We're very accustomed to having very storable fuels.  We might have to accept some change in that model.  If the energy is there to do work, we might use it most when it's available, freeze icecubes, drive loads, boil the water, and use the 'downtime' to process the yields, or sleep, play soccer.

I am curious to see what the flywheel tech is up to  these days.. and I still think gravity is an easy constant to store the energy inputs with.  (Hang weights.. lots of them).. or pumped hydro, hydro permitting. (Tidepools)


"At least we can  'Make hay while the sun shines.'.."

I thought you were going to talk about biomass:  it's very inefficient for liquid fuels, but very efficient and easy to store for electrical generation.  It could handle 20% of our electrical generation relatively easily.

You could literally make hay, and store it until winter, or weather lulls, for generation...

I'm too concerned with the Water and Topsoil issues to want to lean on crops for energy, but I've been toying with a 'Kudzu reclamation model', where this invasive, roadside crop is both plentiful and is accessible to transportation.  I guess it would depend on the success of Cellulosic Ethanol Tech.. but it would at least serve a couple of parallel purposes.

No, I'm really into my 'suspended weights' idea.  We could even combine it with a personal storage facitily, so the more crap you've accumulated, the more potential energy storage your 'portfolio' represents.  Make your spare stuff work FOR you, by golly!


A bit of good planning on when to use those energy sources with storable or at least for which the time of use is controllable (hydro, nuclear, pumped storage, battery powered devides etc.) could go a long way to integrating wind and solar into the electric grid.
Flow Cells anyone?
Flow Batteries Ahem~

Just got off work :P

Solar PV is economical when you think about the cost of firing up those NG peaker plants on hot summer afternoons to run air conditioning.  Solar can shave off those peak loads.  If we had "time of day" pricing for electricity, then PV would spread more rapidly.
Good point. Not all kilowatts are the same! And if the solar panels sit on the top of buildings that consume that power, there isn't the efficiency loss as with power from far away.
Solar-thermal can drive the A/C directly, and even make ice for later.  If the entire A/C load can be taken off-line, it sure beats shaving the peaks.

Solar and A/C are a natural match. In this use case you could even make ice for later cooling. And tying a solar unit to AC could be used to chill water vapor out of the air providing a clean water supply.

This use case alone is enough to justify solar panels.

We just need to underwrite the high initial costs.

It seems PV and wind turbines, remembering that the sun doesnt always shine or wind blow, are best suited to have their power used locally, probably via DC to run HVAC compressors and fans primarily, then to charge batteries, and then finally converted to AC for general use or to go to the grid. Is this whats happening?
I remember driving by Barstow CA in the summer of 1984, out in the desert was a large solar thermal power plant. It had acres of mirrors shining on a large central tower. There was so much sunlight shining on the tower from all the mirrors that it was almost painful to look at. Like I say, that was 1984. So what ever came of that installation and its associated technology?
I think you are talking about this.
Here's a recent article on thermal solar electricity generation.  http://www.businessweek.com/technology/content/feb2006/tc20060214_533101.htm
Here's a recent article on thermal solar electricity generation.  http://www.businessweek.com/technology/content/feb2006/tc20060214_533101.htm
Right.  The line focus vapor solar electric idea has always seemed to me to be a better one (in bright sun) than PV.  These people are getting 400C vapor, which can get them about 20% thermal efficiency, at a lot lower cost than PV.  Ought to be getting more attention.
PV is probably better for distributed generation on businesses and houses, etc, solar thermal makes sense for larger grid-tied generation. Solar thermal would clearly require regular maintainance, which is affordable in a large scale power system. One of the great benefits of a pv system is no maintenance for decades.

Again I think we need to look at all alternative sources and what fits best where. I am tired of arguments against one or the other. Each should go where it works best. We ultimatly need all the renewable we can get from all sources.

Agree -each should go where it works best, and we need everything.  Problem is, for every mention of line focus solar thermal or other equally good ideas, we hear 100 or more mentions of PV, as if it were the only solar game around.  I'm just asking for fair and balanced enthusiasm (and money), not poo-pooing any candidate.
Good points
Regarding Solar power in the Northwest, Dana Brandt of Ecotech Energy Systems comments in Whatcom Watch:
We get a skewed perception of how much sun we get here because of our dreary winters. Here's why it's not as bad as it seems--over the course of the year every place on earth gets an average of 12 hours of light and 12 of night each day. Here in Bellingham we get most of our light hours during the summer when we have 16-hour days and eight-hour nights. During the winter we only have 8-hour days and 16-hour nights. It's only during these short winter days that it's so cloudy here. It's bright and beautiful during those long, 16-hour summer days. This is when we generate most of our solar electricity. So, if we generate all our electricity in the summer, what happens in the winter? PV production doesn't stop in the winter, but it does slow down. This is where net metering comes into play. We turn our meters back all summer and then use those credits during the winter.
Being out of Phoenix AZ and involved in the energy field I can tell you it all comes down to cost of installed systems that is the issue.  Present installed pricing is in the $7 to $8 per Watt range for residential grid tie,  commercial is in the $6 to $8 per Watt range.  These need to be halved to be completive with the traditional fossil fuel based generation industries.  On the 31st of this month there is big vote at the ACC downtown on making the utilities increase their renewable to 15% of total generation by 2020.
In Maricopa County that Phoenix is a part of in Arizona, it can accommodate the whole of the USA electrical energy needs using PV.  The present cost base does not allow this event to occur though.
That said the grams of silicon required per Watt is still trending down.  The increased silicon costs due to supply demand issues will reverse in 07.  The Balance of Systems is still trending down and streamlining at a utility level will also help.  Cells efficiencies are still increasing marginally as seen the San Jose show last month where Kyocera announced it was able to get a cell to perform at over 18.5% up from 14.5% in 1989.  I must say the show this year was a blow out event by way of attendance and new products.
Other exciting events include a battery that under testing conditions doing 100% discharges and charges every 6 minutes, over 15,000 times still maintained 85% of the original charge capacity.  Under these test conditions that is a battery that will last a stunning 40 years, the real world model is projected to still give 20 years of real use.  This battery is designed to handle temperature extremes from -60F to 165F, with the same Watt Hours per KG as the NiMh (Nickel Metal Hydrate) batteries.  The 1st generation batteries being manufactured will find their way into the automotive field.  I will be at the SEMA show in Vegas this week and this manufacture will be there if others are going check them out at the Boshart Engineering booth.
Southwest Wind power also at the San Jose show has a grid tied turbine that in a 12 mph wind area will produce at 9 cents per kW hr.
On top of this there is a technique being implemented in the USA today that will boost reserve extractions from certain fields many fold.  
There is plenty of events going on out there, we need to support them to keep this engine going as cleanly as possible.
Geoff S
The article was not too clear about the pricing. First it said GM was getting "a discount to the prevailing rate for electricity in the region." So that sounds like a good deal, electricity less than off the grid! But then it contradicts itself: "the economics only make sense to people who think that prices for conventional energy will keep rising." That wouldn't be true, if the rate was already lower than conventional energy. But then, it contradicts that last statement: "if you think electricity rates will go down, these long-term contracts don't look good." Now the claim is that it makes sense only if rates don't go down, not that it makes sense only if rates do go up.

All in all it's pretty muddled, and this could have been addressed very simply by saying what the rate is that GM is paying.

I agree - I guess they didn't want to completely give away the business model.

I assume the element they are not talking about is that the rates they charge will rise over time. From a cash flow perspective, this is like renting instead buying with a mortagage. Sure the rent might be lower the first year than the mortagage would be but the mortagage stays flat over time while the rent increases. So if you assume that electrical rates will go up, this seems like a winner financially for both sides.

The other aspect they seem to be factoring in from the outsourcing company's perspective is that they might have new revenue sources if carbon trading happens.

Thanks for this upbeat update. I think people talk too much about the price coste. Cost will come down and real cost is rarely an issue when the nation's (world's) power grid is at stake. I don't think investors were pesky about cost when Edison got started. People were willing to pay the cost of nuclear (which is still not clear) and they will go for solar energy just the same way. Hide the first wave of solar in a $0.01 per kWh rate hike and nobody will complain much. That is plenty of money to get started.

And that battery sounds promising. Too promising, maybe. Where is the catch?

The catch is that the energy density (kwhrs/kilo) is still lower than conventional li-ion.

OTOH, that's not so important.  With regenerative braking and electrical motor torque you don't notice it that much.

A123systems's batteries in Dewalt power tools have the same profile: high power, long cycle life, better safety, lower energy density.

Firefly's batteries may beat them all: they're a spinoff of Caterpillar, and promise to start large scale manufacturing next fall. They promise high energy density, high power, long cycle life, and much lower cost than li-ion (cost near that of lead-acid, without the disadvantages).

I got to look into these. I have a battery based product in the market but we built it on NiMH technology (for cost). Current life cycle is 2-3 years and battery replacement is not particularly profitable for us. The customer does not like it, either, a technology with longer life would be welcome.

Thanks for the hints!

Good News, re: Clouds.  At any given time 55% of the Earth's landmass is in sunlight and cloudless.  Given an advanced superconducting worldwide electric grid system solar farms around the world could be linked together so that power could flow all over the world 24/7.  IE., when it's dark in Arizona, the solar farms in Australia and Siberia should be up and vice-versa. If we could distribute the power across national boundaries no one would go w/o electricity anywhere in the world.

Bad News:  The human race consomes a bucketload of energy.  I've done some rough back-of-the-grocery bag calculations on the matter.  All other factors aside, based on the world's current energy consumption I figure the 430MW solar cell plant Nanosolar is building in California could completely replace all other energy sources with solar in something like 6000 years.  On average it could (almost) replace one average power plant per year but there are A LOT of average zized power plants in the world.

"based on the world's current energy consumption I figure the 430MW solar cell plant Nanosolar is building in California could completely replace all other energy sources with solar in something like 6000 years."

True, but we like to think that if the business model is successful, that will not be the last solar cell plant ever built.  Let's set a goal:  When the number of solar cell factories matches the number of auto and truck factories worldwide, we will consider that phase one and then re-evaluate where we stand...and my back of the grocery bag numbers tell me that it probably took under 6000 years to build those car and truck plants! :-)

Also, we assume that other types of energy will be in the mix too, such as wind, and methane recapture, and efficiency efforts will begin to kick in, such as earth bermed housing and business structures, passive solar and daylighting, and ground coupled heat pumps.  And guess what?  There will still be a few BTU'S of fossil fuel such as nat gas, oil, and propane here and there for quiet some time...of course coal is plentiful for awhile, but the carbon release issue should mean that carbon sequestering is a must, and we would still have to concern ourselves with the complete blowing up of whole mountaintops that coal brings with it.

But, I think your major point is essentially correct...it is going to be a tough squeeze, no matter how you look at it...not impossible, but damm tough.

Roger Conner  known to you as ThatsItImout

The key to understanding the 6000 year timescale is exponential growth. Today it takes 6000 years, next year, at 30% growth, it will only take 4600 years. In ten years time that number will be down to 200 years and in 20 years, again at 30% annual growth, it would only take 31 years. The truth is that we can expect a shift to a solar economy within 30-50 years. How long did it take to get away from the steam engine and to power everything with electricity in the late 19th century?
'06 PV installations are about 2.4GW (peak)and growing at 40% growth per year (05 was 1,727 MW), or doubling about every 2 years.  In 10 years at that growth rate, you get 77 GW per year (or about 15 GW average output), or about half of the 2% average growth in electrical demand.  In 20 years, at that growth rate, you get 2,400GW installed PER YEAR, or about 450GW average output.

Given that worldwide average output is only about 1,700 GW, we're not that far away.

I would shy away from 40% growth being sustainable for two decades. But we can probably keep the 30-40% going for a couple more years and then expect something in the upper 20% bracket for a decade or so. It would, of course, be great to get more growth. Theoretically there are few limits. Raw materials, processing technology and assembly are rather low-tech and well understood for silicon technology. It looks like we will pass the 1GW average output growth per year in just a year or two. From then on one can really count solar energy in power plant equivalents. I think that will make accounting and advertising a lot more efficient.

Solar and renewables in general have come a long way since they were discussed seriously in the 1970s and 1980s.

Take a look at this thread from top to bottom so far.  Many, many good  highly informed, enthusiastic notes on PV.  Once in a while a little comment on solar thermal.

But isn't it true that solar thermal gives us more kw-hrs/yr by far than PV at this time?  And isn't it true that solar thermal, like PV, has lots of potential for improvement?  And isn't it true that solar thermal is cheaper by far at present- all costs included, including upkeep? And isn't it true that the horse leading the race at the start is often the winner at the end?

And not to forget, if you are going to use a point concentrator, a stirling, right now (see NASA) can give you 35% efficiency at an engine-alternator cost of about $200/watt (manufacturers estimate based on materials, fits, etc)- AND a life of about 100,000hrs.

So, how come so much here on PV and so little on solar thermal?

Again, I'm not trying to belittle any solar technology, just asking for a fair allocation of time, resources, enthusiasm, insight, innovation, brains, and all that good stuff- maybe in proportion to delivered kw-hrs/dollar.

Or maybe solar thermal just ain't hard enough.  PV, like fusion, is a lot more challenging and hence more fun and hence gets more  brain power and  more talked about?

But is talk our goal?

Interesting questions.

I guess I like PV better than thermal for the same reason I like electric vehicles better than bio-fuels (even if bio-fuels didn't have other problems): they're a consumer-side technology, rather than supplier side.

PV can take off without any involvement at all from utilities, individuals can make a difference, and they can take charge of their energy costs & supply.

That said, you're right: solar thermal could be just as useful as wind in the right locations.  It has seemed not very advanced, but of course the recent CA projects are pretty large.

I'll have to research it.  Any suggestions for particularly good sources?

"an engine-alternator cost of about $200/watt "

Am I reading that correctly?  That would suggest that a 1 kilowatt system would cost $200,000.

Nick, you are too polite.  $200/watt is a goof.  Here I was again in the wee hours, typing in a semi-blind condition, and making the same kind of error I have poked jibes about when others do it.  Let him who is without sin cast the first sneer.  I meant $200/KILOwatt.

And of course the next question is " What's your source for that number?" .

Source is the rustbelt dirty handed guys who come by and look at the drawings and say "This ain't nothin' unusual.  I know how to make stuff like that, and for such and such numbers of units I can give you so and so price,"

And of course, that's the price of the engine-alternator only.  The concentrator, tracker and rest of system has to add to that-quite a bit.

So, as I and others have said.  thing to do is set up a huge competition, wherein  everybody  who wants to play brings their favorite solar converter to the same place at the same time and has a big shoot-out, with the winner taking home say E8 bucks.  Then cut 'er loose and stand back.  Everybody wins.


Don't stop posting about solar thermal.

Each time you say something, you give me new ideas. Thank you.

You say: "the rustbelt dirty handed guy who comes by and looks at my drawings and says "This ain't nothin' unusual.  I know how to make stuff like this" "

And I say to myself: why? why does it have to be the usual usual? Can't we revisit the situation from an unusual perspective? Does it always have to be the same old engine-alternator design? is there another way? and if so, what are the implications? Thank you.

(Painting entitled Tunnel Visions)

I was only trying to get across the point that a conventional manufacturer looking at any variant of a current stirling would not see anything scary to make, even tho the configuration itself might be quite unusual.

Not scary can be translated to mean not expensive.

Here's a slightly unusual one- take a 3 or 4 piston double acting free piston stirling and have it pump gas over a remote much bigger turbine-alternator being fed by a slew of such engines, each working from some modest sized point focus collector that won't be too much to handle in a wind.  So maybe a dozen such gas pumpers feeding one turbine-alternator.

The double acting stirling gas pumper is very simple and does away with such things as displacers and concentric fits that bug standard designs. I made a toy version of this config and it worked great.  Nutation was a bit of a bother, so I rejected this design for my living room wood stove generator and used instead an opposed twin ( more parts but no vibration).

well, I'm going to cry uncle over that description ... it's way too fancy for my understanding. Don't give up though. keep plugging away. a simpler design will come into mind.
"So, how come so much here on PV and so little on solar thermal?"

Uh...the thread title is, "Outsourcing Solar Roofs".  Unless you want to talk about solar water heaters then solar thermal is kind of off-topic.  >:)

Mainstream electricity is generated from concentrated heat.
It can go on a rooftop.
Click image for more.

This is exactly the attitude I was arguing about- most people don't even think of anything but PV when they see something like "solar roofs", when in fact, line focus solar thermal fits fine on roofs, and could beat PV on roofs just as it does on the ground- given a lot of clear sun, of course.

Another nice thing about line focus solar thermal- it can be driven by combustion heaters when sun is not there.

"I would shy away from 40% growth being sustainable for two decades. "

It's all a question of costs.  If subsidies are required at present levels then growth will have to taper off.

OTOH, it looks like cost reduction is going to accelerate.  From new entrants like Nanosolar, to the currently largest producer Sharp, there is a consensus that costs will fall dramatically: Sharp recently projected a 50% drop in costs by 2010, another 50% by 2020, and another by 2030.

"BERLIN - Japan's Sharp Corp., the world's biggest maker of solar cells, expects the cost of generating solar power to halve by 2010 and to be comparable with that of nuclear power by 2030, Sharp's president said.

"By the year 2010 we'll be able to halve generation costs," Katsuhiko Machida said on Thursday.

"By 2020 we expect a further reduction - half of 2010 - and by 2030 we expect half the 2020 level.

"By 2030 the cost will be comparable to electricity produced by a nuclear power plant," said Machida, speaking on the fringes of the IFA trade fair in Berlin, the world's biggest consumer electronics fair.

Asked how the costs were likely to compare with those for producing electricity from fossil fuels such as coal, Machida replied: "Fossil fuel resources will be totally out by then.""

CitizenRe has launched a solar outsourcing service for residences. They install, own, and maintain the photovoltaic system on the customer's house and charge the customer based on their monthly KWH usage using a fixed rate that is locked in for a 5-year or 25 year period. Under the 25-year rates, the price per KWH is competitive and often better than that offered by traditional electric utilities, even in states like Virginia that have relatively low electric rates. I am paying 8.91 cents per KWH over the next 25 years for a PV system that will be installed next year. I am currently paying VA Power 9.44 cents per KWH. Take a look at www.affordablephotovoltaics.com and see how you can save money and CO2 by purchasing outsourced solar electric power.