Will Residential Power Systems Disrupt the Grid?

This is a guest post by Steve Piper. Steve has a M. S. in Public Management and has been a consultant in the utilities business (primarily electricity) for the last 20 years.

A couple of months ago, posters on The Oil Drum raised the question of whether installing large amounts of grid-connected power at the residential level (solar panels, small wind turbines, and the like) would disrupt the grid.

There is a standard (IEEE 1547) covering safe interconnection of small power facilities to the grid. Comparing the amount of increase likely in solar panels and in residential wind turbines with the allowances for disruptions of various types in standard IEEE 1547, it appears that the adding these devices should not be unduly disruptive. The only exception might be in areas with unusually high grid penetrations of these auxiliary devices.

Market Prospects for Residential Power Systems

Policy initiatives in electricity generation have increasingly encouraged installation of residential/small power systems as a way of reducing reliance on central-station fossil fuels. Many of these systems, including solar photovoltaics, small wind turbines, or low head hydro, produce no greenhouse gases when they generate electricity, allowing them to be included in Renewable Portfolio Standards (RPS) promulgated in many states. According to the U.S. Department of Energy’s Database of State Incentives for Renewable Energy, 29 states have enacted explicit targets for renewable energy production, and 16 states of the 29 have goals for production of energy from ‘distributed generation’ or generation below the substation level.

To meet RPS standards, several states (either directly or through their jurisdictional utilities) have rebates, leasing programs, and other incentives to encourage residential renewable energy systems. Additionally, the recently enacted federal stimulus package eliminated the $2000 cap on residential renewable energy systems, leaving in place an Income Tax Credit equal to 30% of the total project cost. These provisions of the stimulus legislation expire at the end of 2016.

The combination of state incentives and the federal tax credit can make residential renewable systems attractive to homeowners. DOE’s National Renewable Energy Laboratory (NREL) recently forecast that these incentives would drive cumulative pv capacity installation to 24 GW by 2015, an eight-fold increase from today. While this would put solar pv at about 2% of installed generating capacity by that time, pv would contribute a bit less than 1% of total electricity. Where states encourage residential renewable energy systems we might expect higher rates of penetration, balanced out by lower rates in states that don’t have RPS and/or provisions for distributed generation.

Technical Issues for Interconnecting Residential Power Systems

Electric utilities recognized at the start of the decade that increasing penetration of power systems below the substation level could present problems to the electric grid. The standards-setting body IEEE (for Institute of Electrical and Electronics Engineers) convened committees to determine minimum characteristics for safe interconnection, referred to now as IEEE Standard 1547. There are a number of technical provisions of IEEE 1547, but the most noteworthy standards are as follows:

1. If interconnected distributed generation causes backfeeding or ‘islanding’ the generator must be able to disconnect until the condition is cleared;

2. Total distributed generation feeding the distribution circuits cannot contribute more than 10% of the circuit’s maximum fault current.

3. Total distributed generation feeding the distribution circuits connected to a given substation cannot total more than 15% of the substation’s annual peak load;

‘Islanding’ describes a matching of generation and load within the distribution circuit system that creates a subsystem essentially independent of the grid’s central control. One might expect this to happen when local generation is high and grid usage is low, if no built in cut-off of the auxiliary devices takes place. Islanding causes reliability and quality problems in managing grid power.

Bullet item 1 amounts to a technology requirement. Modern grid tie inverters are certified to IEEE 1547, meaning they can respond to backfeed and islanding by shutting off the distributed generation. Grid tie inverters are most often associated with solar pv systems but can be used for small wind generators and other systems that produce DC power.

Other types of distributed generation (micro turbines, wind, or small hydro) can deliver synchronized AC power to the grid, but require upgrades to the circuit to address backfeeding and islanding. These upgrades include addition of reverse power relays and directional power relays that detect the adverse conditions and reduce or shut down distributed generation.

If the number of homes installing distributed generation off of a typical substation remains small (100 or fewer homes) backfeed or islanding conditions resulting in disconnection would be highly unusual. A typical substation might be rated for 10 MW of demand and serve 3-4 thousand residential customers. Disconnections for backfeed would occur during power outages on the circuit.

The current and load limits (bullet items 2 and 3 above) restrict the amount of distributed generation that can be installed on each circuit. Grid tie inverters contribute no fault current, so they are governed by the load limit. DG that does not use an inverter is governed by the current limit.1

The load limit of 15% will act to limit penetration to levels lower than 15%, because of the uneven nature of locally generated power. Solar pv systems, for instance, run close to their full output at the height of a sunny day, but contribute relatively little energy (15-20% annual capacity factor). Homes that wanted to tie to the grid and offset substantially all of their utility usage might have a 5 kW system installed. For our 10 MW substation this standard might accommodate 300 homes (300 X 5kW = 1500 kW, or 15% of substation peak load). The indirect result of Bullet 3 is that instead of being able to add 15% of resources such as wind or PV, one can add perhaps half this, depending on the variability of the resource.


Some areas of the country are experiencing increasing amounts of distributed generation, especially solar pv. Even with the rapid penetration of distributed generation expected by organizations such as NREL, it does not appear that it will approach limitations on circuit capacity (per IEEE 1547) soon. However, the load and current restrictions may pinch in areas where interest in (and subsidy of) distributed generation is very high. At the same time IEEE 1547 is a work in progress, and will likely be revised as utility experience with distributed generation grows.

1 Many thanks to John Kueck of Oak Ridge National Laboratories for his guidance on these aspects of IEEE 1547.

Thanks for investigating this.

Has anyone run into a situation where putting flow back on to the grid is an issue? I know in Hawaii, the issue came up, because quite a number of people were using solar panels, because of the high price of petroleum.

This is link to an article I saw about US solar panel use:

I know in Hawaii, the issue came up, because quite a number of people were using solar panels, because of the high price of petroleum.

This issue is hardly based on technical facts.

In Germany a single family house with an electric hot water heater has to be capable to draw 34 kVA from the grid.

So obviously a single house can also feed 34 kW into the grid, which however is almost impossible as the area on the roof is simply not sufficient to generate 34 kW with PV or a small wind turbine.
Besides, even if it was possible, an average German household requires 3500 kWh per year, so there's no reason to put significantly more than 4 kW of PV on ones roof. (Besides, even if each house had a monster-PV-system on its roof, since each PV system has a different angle, different shadowing, and different modules peak power of all PV systems will never be reached at the same time.)

And even if American houses had puny electricity connections, which is doubtful since the electricity consumption per capita in the US is doubled compared to Germany, most PV system would obviously be placed in regions with high sun irradiation which are also regions where lots of air conditioning power is required and thus more PV will reduce the load on the grid and not increase it.

And since most American households are inefficient, they are more likely to buy efficient appliances than to put a PV system on the roof in the first place. No-one in his/her right mind puts a PV system on his/her roof just to power an inefficient air conditioner, an inefficient fridge, an inefficient freezer, an inefficient hot water heater, an inefficient electric heater, inefficient lighting and ignores proper insulation.
It is cheaper to save electricity than to produce electricity.

In addition, PV is more expensive than solar hot water and Americans don't even install solar hot water (which btw doesn't feed electricity into the grid), so why even worry about PV installations on US houses in the first place?

Solar hot water capacity added worldwide (2008):
China: 80.2 %
USA: 0.5 %

In Germany a single family house with an electric hot water heater has to be capable to draw 34 kVA from the grid.

Thanks for providing the link, but I'm confused by this. Why would a house need a circuit capable of drawing an amount of power that is 90 times the household's average hourly load? Peak demand on a single residence is typically 1.5-2 times average hourly load. I translated the page, but feel like I'm missing something...

Because it is designed for the worst case scenario, if everything is turned on at the same time:
Electric water heater, oven, stove, vacuum cleaner, hair dryer, fridge, freezer, washing machine, laundry dryer, dish washer, electric iron, sauna, 500W halogen lamps etc.

In Germany a single family house with an electric hot water heater has to be capable to draw 34 kVA from the grid.

But that jut gives up an upper bound for a single house. The grid is more concerned about all the houses on the substation. Any decent analysis will look at the variances, and covariances of the component to come up with a model for the variation of the whole system, which percentage wise will be very much less than the variation of the individual components. Obviously solar will add more variance, but reduce the average load, so the system variance as a fraction of total will lieky rise. Also the solar covariance is quite high. Most panels will be facing south or a little off from south, otherwise the economics of the panels is poor.

I'm sure the existing standard is designed with the spirit, keep the penetration below X%, and you (grid manager) need not worry about it. Beyond that they have to start carefully managing it in order to insure system stability.

Also the solar covariance is quite high. Most panels will be facing south or a little off from south, otherwise the economics of the panels is poor.

And some will be placed on a facade and others will be placed flat on a roof and others will be placed in any angle between 0 and 90 degrees (facing south) and some will be covered by shadow.

Beyond that they have to start carefully managing it in order to insure system stability.

For instance that the hot water heater would automatically turn on at full PV power, which doesn't sound too difficult to control at least not in 2030 when you may experience a high PV penetration.

You say:

No-one in his/her right mind puts a PV system on his/her roof just to power an inefficient air conditioner, an inefficient fridge, an inefficient freezer, an inefficient hot water heater, an inefficient electric heater, inefficient lighting and ignores proper insulation.

There are plenty of sane clueless fools in the world. I have no doubt that plenty of houses with PV on them have inefficient appliances.

My experience and conversations with others with respect to PV installation is that you can get a kind of "Prius Effect", once you have the instantaneous data you start connecting the dots of what is using power when and you start engaging the throttle in a more nuanced manner. If I tell my spouse that the use of the dishwasher and washing machine is essentially free during the day (a gross simplification) or "carbon free" (more simplification), we both begin to shift that usage. We also begin to reconsider our use of certain things like the microwave as we see our load go from a steady 500watts to 2000 watts during its usage (I think the response was "wow"). The efficiency of appliances that break become a REAL conversation. While we had long ago changed our lighting and water heating, and more recently put in plug load control

http://www.wattstopper.com/products/productline_list.html?category=122&t... (a device worth its weight in gold)

we became more diligent in finding vampire power usage once we had that instantaneous monitoring, having that little screen on in the kitchen just makes
one more sensitive in this area. Maybe I should make the argument that the grid tie system with the screen without a single panel might be enough to change
some people's psychology on saving energy.

I have no doubt that plenty of houses with PV on them have inefficient appliances.

Even if this were to be the case, this just increases the chance that the power from the roof is not fed into the grid.

Can anyone explain why there seems to be such poor take up of Solar thermal domestic water heating in the US especially when most of the states have such Ideal conditions.
Considering the installed cost per Kw is less with effiency of 70~80% versus PV 8~15%. A 200l (45 gal)tank can store up to 14Kw/Hr for up to two days. No need for complicated solar controlers which will be come increaslingly had to maintain post Peak. The main draw back with grid tie PV systems is when the mains goes it automaticaly cuts off you PV system.thes system only works with a BAU mains.

As a side note it is very easy to set up PV systems to dump excess power directly to your immersion using a current sensing relay. Any decent electrican shoud be able do do this for you. But most instalers go blank when you ask them as they are only intersted in fitting the basic systems uot of the box

Hi Rib,

I think the short answer is that the economics work against it. We're quite frugal in our use of hot water, so our water heating costs are less than $150.00 a year -- approximately 1,200 kWh @ $0.12 per kWh. If a solar system could cut these costs by two-thirds, our savings would be less than $10.00 a month; triple our consumption so that it's more in line with a typical household and we net about $300.00 a year.

If DHW costs represent any significant portion of the monthly household budget, affordability will likely be the key stumbling block. Alternatively, if one is of sufficient means, then hot water costs are not on the radar (some other motivation would be required).


Thanks for the reply.
I see what you mean it would take about 15 years for the average used to pay off a system.
I check my own bill just my bills to confirm our prices. I am paying $0.08Kw/Hr for gas $0.25Kw/Hr for power and use about 1200KwHr for water heating so after rebates (300EuroM2 vacuum solar) I hope to pay system off in about 5-7 years depending on power price
There is no rebate system yet for PV in Ireland.
Also just to make your day we are paying $6.27 GalUs for Gas 95 Oct and loos as thoug we are to get a Carbon Tax on fuel of $0.43gal from Nov.

Thanks, Rib, for confirming your energy costs and congratulations on the purchase and installation of your DHW system; it sounds like a smart investment. There is no natural gas service in this province, except for a few hundred homes served by a small distribution system, so fuel oil and electricity are our two principal choices. Fuel oil retails for about $0.75 per litre and electricity is priced at just under $0.12 per kWh (elsewhere in Canada, it sells for as little as half that).

Most Canadian homes are equipped with natural gas or electric storage cylinders and their operating costs are extremely low by world standards; the downside, of course, is that there is no real incentive to use hot water wisely and renewables are priced out of the market. The situation may improve over time, but it won't happen overnight.


Gail -

I fully recognize that all sorts of problems can arise once solar and/or wind power exceeds a certain percentage of a grid's normal power output. It is not a trivial problem. I do not have the expertise in power distribution to comment on the reasonableness of the recommended limits set forth in IEEE Standard 1547.

However, like most industry trade group standards, these are very likely the work of a committee and are probably quite conservative (after all, a standard-setting group doesn't want to be criticized or held liable if someone follows the standard and thing still go wrong).

We must also recognize that for the most part the US electrical power industry loathes solar and wind power, for a number of reasons, including but not limited to: i) grid problems as discussed in the post, ii) solar/ wind power is a disruptive interloper, interfering with what they're used to doing, i.e., burn fuel to make and then sell electricity, and iii) with solar/wind there are no cute games that can be played with fuel price escalators and fuel surcharges.

The established electrical power industry is hardly a friend of renewable energy. Many have spent a considerable amount of time, money, and political capital trying to scuttle proposed wind power projects that might chip away at their control and bottom-line profits.

Hi Joule -

I don't think it is quite as black and white as you say. Keep in mind we have a few hundred electric utilities across North America. Many of them behave exactly as you indicate, many are simply resistant to change, and some are supportive of expanding renewables.

The IEEE 1547 standard itself seems conservative. I think this is more reflective of a conservative engineering culture whose primary mission is high reliability rather than a deep-seated antipathy to renewables or distributed generation.

some are supportive of expanding renewables

If people produce their own power on their roofs, utilities obviously lose business. I don't see why an utility would support this.

Under traditional utility regulation, you are absolutely correct.

However, states with a revenue decoupling/true-up mechanism, such as California, are positively incented to pursue the least expensive means of delivering electricity services, including energy efficiency (=lost sales). It is one of the reasons California utilities can pursue solar wholeheartedly.

Eight states have a revenue/sales decoupling mechanism in place, and another 16 or so are investigating it.

In certain areas of the US, it can be difficult if not impossible to build new power plants. This can be because of siting issues, and EPA and other regulations. With an expanding population, the utility company could have a hard time meeting new demand. So rather than expanding production, they are looking at ways to cut consumption. Where I live, the electric utility will provide a $1,000 cash rebate if you install a solar hot water system. They also have rebates for energy efficient appliances and for light bulbs. Our City Council has waived permit fees for solar PV.

I don't see why an utility would support this.

Sometimes it's crammed down their throats. Colorado voters approved an initiative that requires a certain portion of the electricity provided by larger utilities to be solar, and a portion of that to be generated at the customers' location. The utilities are required to provide a rebate program with a minimum of $2/watt for customer-installed generating capacity. Xcel, the largest utility, offers $3.50/watt in order to increase the number of grid-tied installations.

Despite that, earlier this year Xcel issued a request for bids for 600 MW of commercial solar power capacity, which will be constructed in the southern part of the state where solar flux is best for the purpose.

steve_piper -

While there may be some electric utilities out there who take a favorable position re renewables, I strongly suspect that most have the mindset of our own Delmarva Power, the main power provider for Delaware and parts of Maryland and Virginia on the Delmarva peninsula.

To make a very long and shameful story short, a company called Blue Water Wind had proposed to build an offshore windfarm off the coast of southern Delaware. Previously enacted legislation would have required Delmarva to buy a certain amount of power from renewable sources, so if Blue Water Wind built the wind farm, Delmarva would be locked into a negotiated contract to buy power from Blue Water.

Delmarva did everything in its power to scuttle the whole thing. They really pulled out all the stops. Their lawyers were lawyering, their consultants were cranking out documents favorable to Delmarva and unfavorable to wind power, and their lobbyists were busy working on Delmarva's chums in the legislature down in Dover. A lot of unseemly and nasty politics was taking place. To add insult to injury, Delmarva tried to get the expenses it incurred in fighting the wind farm dumped on its customers. For a while, it looked like the fix was in. Only steadily growing public support for the project, combined with public disgust at the antics of Delmarva and the boys in Dover, prevented the whole thing from being killed before it even got off the ground.

As it is, Blue Water's parent company is in financial trouble, and with financing the way it is these days, it is unclear if the wind farm project will ever get built. Delmarva may get its wish after all.

So, as you can see, my own local experience with electric power companies vis-a-vis renewables has been anything but positive, to say the least. And I'm sure this is hardly an isolated case.

joule --

It sounds to me like an unholy mess. It reminds me of the whole Cape Wind fiasco, in which wealthy Nantucket islanders mounted an aggressive campaign against a proposed offshore wind project. Even the Kennedys, with all their green cred, were enlisted to fight the project. I think it also gained approval but is having similar problems to Blue Water.

If Blue Water's project could be seen within a 20 minute yacht ride of Rehoboth Beach, then herein may be the problem. (sigh...)

steve_piper -

No, unlike the Nantucket situation, it wasn't residents' opposition that was the driving force (though there was indeed a tiny amount of that), but rather a concerted and well-organized effort by Delmarva and its political cronies in Dover to strangle this baby in its crib. It almost worked.

Throughout this whole sordid episode, good faith was in very short supply.

Simple as that.

Steve volunteered to look into what the obstacles were. He ran across this industry standard, and he is saying it does not appears to be a huge problem.

I don't think anyone is saying anything about the reasonableness of IEEE Standard 1547. Steve mentions that there are possibilities is may change in the future.

In the leadup to the Iraq war, president Bush warned the 'coalition of the not-yet-willing' that their refusal to join could leave them increasingly isolated in world affairs. My reaction to his saying that was that the opposite problem was the real concern, that the US (and allies?) would ultimately be the isolated ones, while all the 'littler' nations formed stronger bonds in order to remain secure around such a neighborhood bully.

This is the problem I have with the presumption of this post. It is being outlined as distributed generation threatening the power stability offered by the grid, when it seems to me that it's the insecurity of relying entirely upon the grid that has created the market for DG in the first place, while another level of 'power insecurity' keeps the utilities that run the grid intent upon hamstringing the growth in this sector. Frankly, this could be a useful and productive growth area for the economy that could productively displace some of the lost activity in the auto sector. If there's really a limit to how much DG the utility wants to accept, there are surely ways for a homeowner to use their power directly when the sun shines, and just keep a limited amount connected to the grid-tie inverter. (heat water, cook food, precompress refrigerant for the icebox,)

This isn't solar/wind/microhydro's problem. This is the utility/grid's problem, and if they don't want to miss the boat and see increasing numbers of homes go off-grid entirely, they can find ways to keep themselves from getting isolated. 'Too much solar', as if! ..that should be the worst of our problems.

I refer to this phenomenon as the "enronization" of the grid -- in the '90s Enron lobbied for regulatory changes (please don't call it "deregulation") which would allow them and a few others to build enormous utility generating and "trading" monopolies, foisting off the burden of grid maintenance on the public. Enron is gone now, but a few of its cousins survive. Nothing was ever done after their collapse to correct the regulatory distortions they created.

So we have the same problem as with the financial industry, the utilities are "too big to fail" and require massive inputs of money in order to survive...

The problems that could be caused by unregulated connections to the grid are real and technically based. They're not simply boogey men made up by the utilities to discourage DG -- even if they may sometimes be used that way. If those who were dissatisfied with grid service really wanted to go off-grid, that would be their choice. Nobody would have a problem with it. But that's not what they want. They overwhelmingly want to be able to draw grid power when their own DG resource isn't producing, and sell power to the grid when their DG is producing more than they need.

That can be accommodated as well, but it requires rules and standards that most DG advocates don't understand. IEEE 1547 provides a workable basis, as long as the degree of DG penetration is small. For higher levels of penetration, there is no existing standard. One could and should be developed, but it's the familiar problem of trying to herd cats. It's certain to involve added equipment costs and restrictions that the DG community will resist.

The problems that could be caused by unregulated connections to the grid are real and technically based.

So if a homeowner installs a sauna and a whirlpool and randomly increases the load on the grid, that is no problem at all, but if the same homeowner installs a PV system on his roof and reduces the load on the grid, that may lead to a grid collapse...

If a homeowner does anything, no one cares. If a whole lot of people place a lot of unexpected load or put a lot of unexpected power into the grid, then that is a problem for grid stability. And if we are not talking about widespread adoption, then who really cares?


The problem I'm having with the setup of this post, is that it is angled like those pieces that tell you if you save your money, you're hurting the economy. Put up solar, and you might hurt the grid. It's backwards.. it SHOULD read, How can we make the grid better so it can support DG?

Even in your response above, you implied that this is countering some defense of unregulated grid connections. I'm sure there are some rebels out there who still want to go commando with their systems AND grid tie it.. but EVERYONE I have ever run into and talked Solar PV with has been more than willing to accept that if we own our own source of generation, we have a responsibility to keep the power we output clean and safe.

The idea that it's going to overwhelm local substations, when in the US, we don't even have single digit penetration in more than a couple markets -sounds like an alarm that's being rung for a different fire.

.. it SHOULD read, How can we make the grid better so it can support DG?

Agreed. That's the question we want to be asking.

It already has a partial answer: IEEE 1547. All grid-tie inverters sold commercially, I believe, conform to that standard, and it does include "anti-islanding" provisions that address the key safety issue that utilities raise with grid-tied solar installations.

Unfortunately, it solves it in a way that is guaranteed to cause trouble, if the regional penetration level for grid-tied solar installations gets too large. Exactly what "too large" means, or even what defines "regional", is hard to pin down. Going at it from the other side, what one can say for sure is that if the contribution from DG to a local distribution subnet is no more than 10%, then DG resources tied in through IEEE 1547-compliant equipment will be safe and will not cause any problems with grid stability.

There's also an answer for higher penetration levels: responsive energy storage. But there's no standard for how that's to be done. Nor is there any common agreement for who's responsible, or how the cost is to be borne.

"Responsive" implies some degree of knowledge of the state of the supply and load at the point where the storage is connected. That knowledge could come simply from monitoring the frequency, voltage, and power flow in the distribution line at the connection point, or it could come more directly via the utility's SCADA computer system (System Control and Data Acquisition). If the SCADA system is used, there are various options for how the data link should work and whether the channel is one-way or two-way. Getting all the essential players lined up on these issues is where the problem of "herding cats" comes in.

From a technical viewpoint, and also in terms of cost efficiency, I'm strongly in favor of the "neighborhood area storage" approach that DIYer mentions elswhere in these comments. That makes a lot more sense to me than requiring that each individual system that's tied in include some amount of responsive storage.

thanks for the reply, roger.

your Energy Pulse article was very informative, by the way.

i'm not an ee by any means, but i still shuffle some thoughts around the question of structuring the communications that would make a more stable and resilient system, be it on a subcarrier freq on the powerline itself, web-based, phone based, radio etc. I would tend to lean towards a paralleled system, which might mean both/and, not either/or.. while I realise that means a much more expensive and probably complicated solution.. but I would also suggest that if we have gotten to the state where the penetration of DG is as high as that 10-20%, that there would already have developed a number of tools for this kind of power management from at least the other end of the equation, as these producers would have become more aware of their contribution, and would insist on data and control apps which would allow them to sell and buy power with regard to price, etc.. leading me to conclude that many such programs would be web and computer driven.

but overall, i agree that newer, smarter controls are increasingly needed. I am just going to press my point once more that it's unfortunate that many of these topics seem to start in with a tone that says 'tut, tut, Solar might be bad for us, is Windpower dangerous?' Sure, i'm probably oversensitive to criticism of renewables.. but some of the things they are getting criticised for are such distraction arguments. 'I won't touch milk. I know a guy who choked on it.'

anyway, thanks.

Roger - Who actually owns "the grid"?


Well, that's the problem, isn't it. No clearcut answer.

Frankly, this could be a useful and productive growth area for the economy that could productively displace some of the lost activity in the auto sector.

Interestingly in Fremont California, which is reeling over the closing of the NUMMI automobile generating plant, Solyndra ( glass tube mounted thing film PV) is expanding and expecting to employ something like 2000 (NUMMI had employed 4700), they are looking at the NUMMI plant as a potential production plant.

I think there's a place for Neighborhood Area Storage here. NaS batteries on the corner alongside those Telco RT boxes. A reasonable peering arrangement with the larger utility grid could allow them to operate independently as legitimate "islands" if need be for a few hours at a time.

The NaS boxes could shave the peaks and fill in the valleys, relieving the burden on the grid.

It cost much more to store power than the average costs, It's .14-.20 USD/kWh to store in Lead Acid Batteries. I guess the 2 costs will meet
at somepoint.

Have to look at PV in a new light, it's a different game now since prices have fallen so much in last 8 months. I'm installing PV where 12 months ago I was planning on small wind. So few places actually have great wind resources.

Also Of Interest - the latest Summary of Feed In Tariff's.


It's .14-.20 USD/kWh to store in Lead Acid Batteries.

Thus the need for NaS batteries. I don't think we can reasonably evaluate the cost per kWh, since they are still considered "exotic" and not many companies make them. But the prospects are good for NaS prices to fall, however, since they are made of abundant materials: sodium, aluminum, oxygen, sulfur, and stainless steel. A little copper for the wiring, maybe some nichrome heating elements. The insulation can be fiberglass or rockwool. More exotic things like vanadium-redox batteries depend on less-abundant vanadium, for example.

That and the neighborhood approach: rather than each homeowner trying to manage an acid-spewing toxic stack of golf cart batteries in his or her garage, you have one battery array for maybe several dozen households. Might be useful for grid relief even in the absence of universal rooftop solar arrays.

But the prospects are good for NaS prices to fall, however, since they are made of abundant materials: sodium, aluminum, oxygen, sulfur, and stainless steel. A little copper for the wiring, maybe some nichrome heating elements.

I am not quite as optimistic as you about falling NaS prices although there are probably some economies of scale that can be achieved. NGK Insulators is the only manufacturer, but they have been doing it since 1995. My impression is that the expensive part of the process is the manufacture of the ß-alumina electrolyte tubes which separate the sodium and sulfur electrodes. The materials are abundant (aluminum and oxygen) but the manufacturing process is difficult.

In a recent announcement of an agreement by NGK Insulators to provide 150MW of NAS batteries the the French electric power firm EDF the midrange of the quoted cost is US $365 million or $2433/kW. The quoted power ratings are for 100% DOD. At a more likely operation point of 85% DOD the power rating is 10% higher so the cost per kW is US $2190. At 85% DOD the quoted lifetime performance is 4500 cycles of 6 hours length. Therefore the cost/kWh is $0.08 plus the cost of interest.

In addition the batteries are only 75% efficient in AC mode so that you have to add on 1/3 of the base generation cost for any kWh that resides in the battery.

Keep also in mind that many of these feed-in tariffs are strictly capped.

(For instance Switzerland has also feed-in tariffs for PV, but since they are capped, the entire years budget was used up in one day.

Interesting also:
UBS saved by the tax-payer due to their record loss paid 7 billion CHF in bonuses (2008).
Swiss feed-in tariffs for PV (2009): 0.01 billion CHF ).

That's the rub: the utility monopoly won't invest more than a token amount in grid improvement unless it will increase its revenue. DG does not increase its revenue, so it will "harm the grid".

In March 2005, EnergyPulse published an article I wrote about IEEE 1547. It discussed its limitations and the eventual need for something more advanced. The article is here.

Hi Roger --

Thank you for providing this link and your input. It's useful to have more understanding of how grid issues interact with DG supply.

Excellent article, Roger.  Kudos.  I'm going to be using this as a resource for people not up on the issues.

The combination of state incentives and the federal tax credit can make residential renewable systems attractive to homeowners.

Make that "attractive to wealthy homeowners".
Large "tax credits" are virtually useless to large numbers of people. Retired people may have large semi-liquid assets which would enable them to purchase such systems, but they have very low incomes which have little or no taxes assessed and therefore "tax credits" do them no good at all.
"Tax credits" are one more sop to the well to do.

"Tax credits" are one more sop to the well to do.

In some cases, but I can't agree entirely. Not many people consider the mortgage interest deduction a sop to the well to do, but something that helps the middle class afford a home.

PV systems cost around $6000/kW installed, and prices are falling. A homeowner could get 3 kW for an installed price of $12k with just the ITC (no utility rebates). Maybe tough to afford in a recession, but not out of sight for the middle class...

There was a company in CA that was approaching large box stores and warehouses, installing PV panels on the roofs at their cost and getting the utility customer to agree to pay the going rate of electricity for a period of say 7 years (that # is a guess, I haven't looked at the program in years). At the end of the lease the customer owned the panels and the investor who paid for the panels got a nice return.

The problem was that it was so successful that it sucked all of the available solar incentives from the market leaving everyone else scrambling to mop up what incentives they could before they were used up.


SunEdison is one of the companies doing this in various states. I believe their standard contract is for 20 years, roughly the expected life of the PV panels. SunEdison seems to be focusing recently on government installations for cities, universities, etc, where the client has a large adjacent area of land that is not going to be developed. For Arvada, CO, they will be putting in and operating 3,300 panels on an area adjacent to the water treatment plant.

This type of arrangement seems to make a lot of sense, financially. The customer gets a long-term fixed rate on a portion of their electricity, with all costs for maintenance and such incorporated into that single charge. SunEdison has a long-term contract for each of the installations, assuring the revenue that will allow them to repay investors.

I think the idea of sodium sulphur batteries at substations should be investigated further. Real time records need to be kept of how much each microgenerator owned the stored energy. That energy could be used immediately, sold to others or saved for later.

Conceivably thin film solar could get cheap enough so that it generated enough for each household even on an average winter's day. Excess energy from summer and autumn could be carried over to winter. Online records would say "Fred & Betty Smith, 310 kilowatt hours in storage". Software in the home PC could buy, sell or hold electrical energy according to current prices.

The questions are how much would it cost and would it be secure?

Small storage solutions do exist:

But at this point the grid has no storage/capacity issues.

I am looking to put 600-700w of PV on my garage roof this autumn. This should at my latitude give approximately 550 kwh per annum. The power will be fed via a grid tie inverter (Soladin). No export meter - anything that does go there will be a freebie to the national Grid.

To minimise freebies I have considered my daytime base load wich is

2x14w wireless routers
1 x solar water heating pump - 50w (effectively daytime baseload)
plus 20w of miscellaneous other sources.

I have 2 regrigerators and 2 freezers and intend to put these on time switches to ensure they are drawing power in the daytime.

Also the washing machine and dishwasher

The central heating pump for hot water if it is needed 9rather than in the evening.

Work from home 2-3 days a week so there is the draw from the PC.

Storage is an interesting area to look at, since anything that improves the effective capacity factor of DG will allow more of it to be accommodated. Predictable flows from a battery are an improvement over generation that varies with cloud cover, etc.

Thanks for that link to Deeya Energy. Nice specs; very well suited for off-grid home.

No description of the technology, beyond "patent-pending NASA-derived flow-battery technology". Not sure what that would be; I wasn't aware of any active players in the flow battery arena since VRB Systems went under. The high electrolyte weight in this Deeya Energy system -- 1.4 tons -- is consistent with a vanadium-redox battery. Is this perhaps the Phoenix rising from the ashes of VRB systems?

No AC output. "Inverters not included". And no info on price (of course). I'd love to see a quote.

Here's a presentation about this technology:
(They use a liquid electrolyte without heavy metals but don't appear to disclose more details). This system is, for instance, meant to provide a server with power during a power outage.

As long as hydro power and gas power capacity is order of magnitudes higher than the installed PV-power and as long PV systems are installed in regions with air-conditioning and as long as load can be adapted to the power availability (e.g hot water tank, air conditioner) there's no reason to electrically store PV-power anytime soon.

Thanks again! Good stuff -- though I got very impatient with the slow, drawn-out pace of the presentation.

It wasn't until the very end, in the Q&A session, that someone finally asked the bottom line question about cost. Answer: $12 - 15 thousand for the 2kW / 24 kWhr system that they're currently shipping. Future target $2500 / kW for large containerized systems in the 500kW to 1MW class. That would quite attractive for "firming up" wind farm output and providing ancillary grid services. If they can meet it.

He did describe the technology a bit. It's an iron-chromium redox chemistry studied by NASA in the '70s. Unanswered: why, if the technology is so attractive, did it sit so long on the shelf? (There's reference early in the talk to a recent "breakthrough" in the technology, to which Deeya owns the patent rights, but no indication as to what that breakthrough might be.)

This is silliness. We would be lucky if the current available tech covering one's roof could even offset 25% of the homeowner's power in the first place. I speak for the average case of course. When EV or capacitor cars come, we also have a storage system. Or how about just heating water? The suggestion that the average homeowner could make his home self-sufficient and then contribute a significant surplus to the grid is silly. I don't envision a 1.5 megawatt wind turbine in anyone's backyard soon.

Edit: Sorry, I accused Gail of writing this and would like to undo that.

We would be lucky if the current available tech covering one's roof could even offset 25% of the homeowner's power in the first place.

Not at all silly.

In plenty of locations (though not all), solar pv can provide capacity factors of 15-20%. Taking the average of 17% yields about 7500 kWh per year for a 5kW system. That is pretty close to an average family's usage and well more than 25%. I've had installers tell me that once a pv system goes in, families pay closer attention to their energy usage and figure out ways to net out to zero.

Not true at all. It's easily possible for a house to produce 2 or 3 times the energy used. 25% would be for a very small system.

Not true at all. It's easily possible for a house to produce 2 or 3 times the energy used. 25% would be for a very small system.

True but it could used somewhere else (e.g. office buildings, shopping malls etc.).

The electricity usage per capita in the US is 13,636 kWh.
If you have 4 people living in this house than their total electricity need (incl. work, shopping, travel etc.) is 54,543 kWh.

At 1500 sun-hours you'll need a PV system with 36 kW (even at 20% efficiency that's 180 m2).

This also shows: The US should really think about efficiency before thinking about more power. Efficiency does not affect lifestyle.

The orinal poster (EngineeringPhysicist) said that

We would be lucky if the current available tech covering one's roof could even offset 25% of the homeowner's power in the first place.

You go on to reference per capita electricity consumption and calculate a household consumption (incl. work, shopping travel etc.) at 54,543 kWh (I am assuming per year). That works out at 151.5 kWh per day! That cannot be the electricity consumed by the average US residence housing 4 peolpe so those figures are not relevant to this discussion.

What is relevant is the average household consumption per anum which I was able to get from this table from this EIA web page. At 10,656 kWh/y that works out to 29.2 kWh/day. In a few select locations this could obtained from a 5kW system with more kW being required the less annual average insolation you get. According to the U.S. Solar Radiation Resource Maps: available from the NREL web site a average household should should able to manage with a 20kW system IF IT IS IN ALASKA (worst case).

A typical 200W panel covers 15 sq. ft. so, 20kW would require 1500 sq. ft. of south facing sloped roof which would be difficult to come up with. However this is the system size to offset ALL the homeowners power use so, to offset "even 25%" of that would only require a quarter of 1500 sq. ft. (375) which works out at slighly less than a 20 ft. square area of south facing roof. Technically possible but, expensive since the panels alone for a 5kW system will cost at least $12,500. Since less than 700,000 of the US population of 300+ million live in Alaska, I'd venture that "current available tech covering one's roof could even offset" a lot more than "25% of the homeowner's power in the first place" if the homeowner can afford it. In the "sunbelt" it's definitely worth doing and makes more sense the further panel costs and other inputs fall.

Alan from the islands

Hi Alan,

The number of homes that could accommodate solar arrays of any size is probably a whole lot smaller than we thing. I'm guessing at least half of the homes in North America could be ruled out due to their east-west orientation, various complications with respect to roof angles and cuts and other architectural features, and shading issues (I strike out on all accounts). On top of that, there are aesthetic concerns. Lastly, the question of economics and access to capital -- I don't have $12 to $15K sitting in my cookie jar and given that my utility costs are quite reasonable in relation to my other monthly expenses, I would rather invest my monies where they will do more good. If we could generate even a small fraction of the 1.2 trillion kWh of electricity U.S. households consume each year that would be a truly Herculean accomplishment.


Understood. I was just responding to the OP's assertion that "The suggestion that the average homeowner could make his home self-sufficient and then contribute a significant surplus to the grid is silly." and anyone's 5x overstating of average US household consumption in this context. As all regulars on this site know, your area of expertise is in picking most, if not all of the low hanging fruit and I agree with you that this is the lowest cost "renewable energy" you can find. Using energy saving techniques and efficiency gains alone, North America could probably cut household electricity use by 25% or better.

My own experience has been instructive. I have a desktop computer that I use to log data like the temperature of my concrete slab roof, wind speed and more recently household power consumption. As a result it was never turned off and was consuming 2.88 kWh/day. The CRT monitor attached to it consumed an additional 80W when it was on but was set to go into power saving/standby mode after 3 min of inactivity. I bought a laptop (refurbished), a wireless router and a new very low power "netop" computer to replace the aging desktop. I also figured out how to use remote desktop to access the netop from my laptop over the network so, I very rarely use the CRT attached to the netop.

As a result the netop and wireless router consumes less than 1kWh/day, a savings of 686 kwh/yr. Add to that the saving from using the laptop and instead of the CRT and I'm saving .05kwh for every hour of computer use, maybe another 150 kWh/yr. Based on local high tier electricity rates($0.25), I'm saving more than US$200/yr and with all the stuff costing less than $1,000, costs will be recovered in less than 5 years. The netop alone pays for itself in less than 2 years! In North America where electricity rates are much lower than where I live, the payback period will be double or more. Still replacing power hungry desktops with low power netops is a very sensible move especially when the computer is just being used for office work and web browsing.

Alan from the islands

Hi Alan,

I agree completely. Larger suburban homes where the majority of these bigger arrays would be sited use significantly more electricity than their urban counterparts, i.e., more than the national average. As I believe someone else suggested earlier, a standard 3-ton CAC could easily consume more electricity than what a 2 or 3 kW array might produce in the course of a given day. I think we can safely say there will always be sufficient local load to mop up whatever might be leftover.

Congratulations on your energy savings. Well done! I have an older desktop PC and 24-inch LCD monitor; with the brightness set at its lowest setting, it uses an average of 130-watts. By comparison, my two ThinkPads consume some 25 to 30-watts (my ten-year old 770Z with its 128 MB of RAM and Pentium II processor could be outrun by a passing butterfly, but it continues to soldier on and I don't have the heart to toss it).


and anyone's 5x overstating of average US household consumption in this context.

I didn't say household, I said electricity consumption per capita. Remember, I included shopping malls, office buildings etc.

And I certainly wouldn't dispute that a household can work with less than 500kWh/year and person.

I'm not sure I understand the point you were trying to make. The OP wrote

We would be lucky if the current available tech covering one's roof could even offset 25% of the homeowner's power in the first place.

I understood him to be saying that current technology was incapable of supplying enough power. conservationist responded

Not true at all. It's easily possible for a house to produce 2 or 3 times the energy used. 25% would be for a very small system.

You then responded concluding

At 1500 sun-hours you'll need a PV system with 36 kW (even at 20% efficiency that's 180 m2).

This also shows: The US should really think about efficiency before thinking about more power. Efficiency does not affect lifestyle.

I assume that this would be the size needed for the average home-owner to supply their household's share of the total national consumption. That wouldn't make sense since the whole thrust of this thread is DG. Households generate electricity to offset their own consumption and commercial buildings would do the same. In that context I'm just wondering why you would want to bring commercial requirements into the discussion of a home-owner offsetting his own household consumption?

Alan from the islands

Not true at all. It's easily possible for a house to produce 2 or 3 times the energy used. 25% would be for a very small system.

I agreed with this statement from the very beginning. I can't do more than agreeing, can I?

In that context I'm just wondering why you would want to bring commercial requirements into the discussion of a home-owner offsetting his own household consumption?

Why not? As long as I solely refer to the total consumption per capita and not to the household-consumption there's no reason for you to get all disturbed by this.

Besides large office buildings are probably not capable to provide their power needs with their roof/facade area alone. So an employee may need to install a surplus of PV on his roof to cover his office needs as well.

The number of homes that could accommodate solar arrays of any size is probably a whole lot smaller than we thing.

Actually, I remember reading that 120,000 km2 of the US is built.

If only 10% of that area has roof area, you end up with 12,000 km2.

At a PV efficiency of 15% that's 1,800 GW.

Hi anyone,

There are roughly 53 million owner occupied homes in the United States equipped with central air conditioning systems, which I think is a reasonable starting point. As a simple guess, perhaps half could be ruled out due to issues related to orientation, an unfavourable roof profile and shading. Climate could shave this a little further, e.g., Halifax experiences an average of 122 fog days a year. From this, we can cross off those who have aesthetic objections or who are uninterested for whatever reason. Now we're down to those who can afford to purchase and install such a system and for whom the financial and other perceived benefits are sufficiently attractive to warrant such an investment. Where does that leave us? I have no idea, but I bet it's a tiny fraction of the above.

As I stated elsewhere in this thread, a solar DHW system would save me $100.00 a year on our utility costs, which just ain't gonna cut it. For perhaps one-half the cost, I could install a heat pump water heater that would eliminate the need to run our power guzzling dehumidifier eight months of the year and, in the process, provide all the hot water we require at effectively no charge.


That's the point.
It's not a question of area. It is a question of financing.
And Germany solved this problem with feed-in tariffs.

Hi anyone,

I don't believe generous feed-in tariffs are a sufficient incentive in themselves, although they are critical component. For example, in Ontario, the solar feed-in tariff is stunningly generous; to whit:

Rooftop systems
* Less than 10 kW - 80.2 ¢/kWh
* 10 - 100 kW - 71.2 ¢/kWh
* 100-500 kW - 63.5 ¢/kWh
* Greater than 500 kW - 53.9 ¢/kWh

Ground level systems
* Less than 10 MW - 44.2 ¢/kWh

These rates are guaranteed for 20 years.

The number of Ontario homes feeding power to the provincial grid? Maybe a couple dozen? (I don't honestly know, but my impression is that there hasn't been a whole lot of interest.)


Are you sure that those feed-in tariffs are not capped?
(Many countries have capped feed-in tariffs and thus many PV-proposals sit on a long waiting list.)

Regardless: Ontario may be better suited for wind than for PV.

No cap and Ontario reportedly receives 10 to 15 per cent more sunlight than Germany.


Well it seems that people in Ontario miss an opportunity.

I just did a quick search on Ebay and found complete PV (incl. converter, cables etc.) systems for €2400/kW:

At 25 years warranty you can expect a lifetime of 30 years.

If you assume 1000 sun-hours per year you'll collect 30'000 kWh per kW.

That's a revenue of $24'000 per kW at $0.8 per kW.

I don't disagree. Sadly, most Canadians are completely oblivious to the cost and use of energy or, if they are, grumble a bit and that's largely the extent of it. Europeans are years ahead of us in recognizing the benefits of renewable energy and in their willingness to invest in it.

With respect to wind power -- and we have some of the best wind potential in the world -- we now have 2,854 MW of capacity in place, so we have a long way to catch up to Germany on this front too.

Source: http://www.canwea.ca/farms/wind-farms_e.php


The wild card is, what happens if there is a major discontinuity in world energy supplies like Ghawar going into steep decline and all the crap that would ensue? Your approach assumes a continuation of BAU and no major changes in electricity availability or cost. Given the major sources for electricity in your area, such factors may not be important to you but, other people might want to look at their own situation.

I was going to install a grid tied solar PV system but have reconsidered and will be installing some battery backup as well. God knows what will happen to the largely oil fueled grid on my tropical island when TSHTF.

Alan from the islands

Hi Alan,

If I sound critical of solar energy, it's not because I oppose it — far from it. My point is that it hasn't faired all that well in North America thus far, Canada in particular, and its growth has been stymied for a variety of reasons, not just with respect to its economics. Even in the context of Ontario's generous feed-in tariffs whereby customers are paid ten to twelve times more for the power they produce than that they consume, there's been surprisingly little interest. If solar is to play a larger role in our electrical mix (and that's my hope), we need to better understand the barriers to its adoption.

And, of course, North America is not the world; what works well in Europe and elsewhere may not generate quite the same results in this market and vice-versa. Our individual circumstances vary widely, which ties back to my first point.


Actually, solar wouldn't make sense for me either if I were where you are. Areas at high latitudes just can't make as much power from electricity as areas closer to the equator without significant additional cost.

As for barriers to adoption, there are people on my island who think that driving an SUV and living with their family of 4 in a 5-6 bedroom house with a pool, is more important than owning a PV panel. I know on guy that even has a heated swimming pool but, he doesn't own a single PV Panel.

Point is, there are a fair amount of people who could and would purchase PV systems if they thought "Peak Oil" was a clear and present danger. Fact is most people, unlike most of us here, just don't have a clue as to the challenges we face.

Alan from the islands

We need to distinguish at least three different power levels here.
(1) The direct electrical energy usage of the home.
(2) The total per capita electrical consumption per capita.
(3) The total national energy consumption, including non-electrical energy per capita.
Arguing for residential DG to be compared to (2) or (3) is silly (although if one is trying to become carbon neutral (3) is the relevant number). Clearly commercial/manufacturing sites can also host PV, and more remote utility scale generation sites would also be part of any mix that has overall high renewable penetration.

Per capita figures include industrial and commercial users. Residential use is a fraction of that per capita figure. My household of 3 has an average draw of 1500 watts or 500 watts per person. That is only 4300 kwh per person per year or less than 1/3 of your figure.

Hi Thomas,

U.S. residential consumption as at May 2009 stood at 1.38 trillion kWh/year (source: http://www.eia.doe.gov/cneaf/electricity/epm/table5_1.html). I believe the current population of the United States is 305 million so, if my math is correct, that works out to be just over 4,500 kWh per person. There are roughly 105 million U.S. households, so per household consumption is just about three times that. As I recall, Canada's per capita consumption comes in somewhat higher, so we set an especially poor example.


Written by EngineeringPhysicist:
We would be lucky if the current available tech covering one's roof could even offset 25% of the homeowner's power in the first place.

The roof area of my buildings and porch are 146 m2. With 1,000 W/m2 isolation, 15% efficient PV's and the PV's pointing in a fixed direction, my roof could produce 112 kW·hr / (sunny day) of electricity. If one needs heat, substitute some solar thermal panels for greater efficiency and put a cloths line in the yard.

What is so different in principle between a country being 75% dependent on imported oil and a household being 75% dependent on 'imported' electricity? In both cases the import dependence may be the cheapest option for the moment but there is a heavy cost to supply interruption.

Another poster on TOD once said the advantage of home generation wasn't so much the actual kilowatt hours but the change in habits it produced. If your solar panels are producing 2 kw on a summer's day instead of turning on your 2.5 kw air conditioner to the max you might sweat it out. That way you won't dread getting your power bill.

The problem is that microgeneration costs may not come down. Spain and Germany have said subsidised feed-in tariffs are too expensive. I like the idea of daily allowances for water heating, thermal comfort, cooking, electronic entertainment (eg the internets) and so on. Again it could be expensive if houses have to be rewired.

Spain and Germany have said subsidised feed-in tariffs are too expensive.
The feed-in tariffs are reduced every year and they are not subsidized by the tax-payer. The feed-in tariffs are paid for by the electricity consumer. In Germany it is less than $5 per month per household what they pay for feed-in tariffs. And a study from EON has shown, that if wind power wouldn't exist the households would actually have to pay more than those $5, because wind power (which is paid for independently) reduces the electricity price more than what the consumers pay for the feed-in tariffs as less of the most expensive power plants have to turned on (merit-order effect):

The feed-in tariffs are an excellent tool to increase the PV share on existing roofs and to boost the development in this market.
PV-prices have been coming down rapidly, which wouldn't have happened if wide spread adoption of PV wouldn't have existed in some countries due to feed-in tariffs in the first place.

Keep in mind: If the the feed-in tariffs are low or the penetration of that power option is low (which is still the case even for PV in Germany), its costs are also low.

I talked to our local electric coop about solar. They were only willing to pay 3 cents per kwh for solar power, when we all know that solar is probably some of the more valuable power around, especially compared to peaking power.

Gail, there's a lot of regulatory roadblocks to distributed power generation, such as capacity charges, lack of reasonable rates for power generated, etc. I think posting an article on those issues would be of value too.

Juneau, AK just installed a new hydroelectric plant that increases power capacity by 15% (baseload is 100% hydro also). The power has gone out several times over the past weeks, once they admitted it was difficulty starting up the system. Nobody cares.

So the problem is real, but it is also inconsequential. Deal with it when (if) it happens.

I agree with the Delaware discussion, this seems like spin by power companies to slow subsidy. But subsidy in a declining economy is a dead horse anyway. Look at Spain.

Cold Camel

But subsidy in a declining economy is a dead horse anyway.
It certainly worked for Goldman Sachs and its recent record profit thanks to the generous taxpayer bailout:

Look at Spain.
Spain decided to cap the feed-in-tariffs before the economic crisis started. Besides the solar industry in Spain got $1.5 billion last year and produced jobs and power with it. The worldwide Banksters got several $1000 billion and produced absolutely nothing, but paid themselves record bonuses with it.

I'll take you seriously. You seem to suggest that striving for subsidy/bailout may be a potentially successful PO mitigation approach. Setting the moral issues aside, you still have to contend with the constant brainwashing efforts that tend to backfire. While you personally may understand how to leach off the system, your significant others will take the bait and fail to hedge. They will believe bailouts are eternal and socially good. Just like any Ponzi scheme, you have to understand that to succeed, you have to constantly skim off profits and take them off the table. How many Goldman Sachs wonder boys had their own private SUSTAINABLE Idaho, where none of the neighbors know their day job? Actually, I wouldn't be surprised if a few do.

I doubt there are many GS alumni lurking here, but other TOD regulars do lobby for money for their pet project. I say all social subsidies are wrong, including ones for rail, wind, etc. They are just like the GS boys, just not as successful.

Comparing Spain to the Banksters is a weak arguement, like accepting robbery instead of a bullet. We're looking for solutions, not lesser evils. Try again.

Cold Camel

Feed-in tariffs are no subsidy.

1. It is not paid by tax-payer.

2. It is transparent and it's paid for through the electricity bill.

3. Feed-in tariffs can only be collected if one produces kWh's.

4. If one fails to produce kWh, he'll get absolutely nothing.

5. If one fails to produce kWh, he won't get bailed out.

6. If one fails to produce kWh, he won't get a bonus.

7. If a competitor offers the renewable kW product for less, he'll lose despite the feed-in tariffs.

Btw, Germany introduced feed-in tariffs for wind over 15 years ago.

1. Wind power generated close to 100,000 jobs in Germany:

2. German wind manufacturers EXPORT over 83% of their wind turbines with PROFIT.

3. Wind power reduces Germany's dependence on imported fossil fuels.

4. Wind power reduces Germany's GHG emissions.

5. Wind power is still showing a double digit growth.

6. The most important point is however: Wind REDUCES electricity costs more than what consumers pay for the feed-in tariffs:

Facts clearly show that feed-in tariffs proved to be a successful instrument without supporting losers and without complicated bureaucracy.

We're looking for solutions, not lesser evils. Try again.

If reduction of dependence on imported fossil fuels, an export rate of 83% and cheaper electricity is an evil in your opinion, what is your solution and what is your proven result?

I say all social subsidies are wrong, including ones for rail, wind, etc.

Maybe, but if you want to live in a subsidy-free society, where not even investment-banks get subsidized, you'll probably have to move to a country like Somalia.

I agree, there is no subsidy-free society. But we should stick to the issue of whether some social subsidies are good, like your feed-in-tariffs.

On an aside, I've been to Somalia, and relatively speaking, most Somali will thrive post-Peak. Since they are dropping like flies, it can't get markedly worse.

Actually the amazing thing about Somalia is that CLAN STRUCTURE WORKS, if they could just get rid of the external interference, and once all the non-clan members die. Peak Oil will probably allow that to happen if no oil is discovered. But this is way off subject. Most people refuse to learn from impoverished regions. Like Cuba, we might ought to study Somalia.

Cold Camel

I keep thinking about two things regarding higher penetrations of both solar and wind, for your consideration:

1) With their inherent intermittency it seems they provide none to very little installed capacity; that is, we drive these to their maximum production at any given time and don't have the capacity to drive them further in the event of an unanticipated increase in load or the loss of any other resource. I can't shake the thought that large-scale renewables can't displace the building of other forms of non-intermittent capacity to meet system demand. Sure, we might not have to run them as often but the fixed costs of that capacity are still present.

2) PV through a grid tied inverter cannot provide for any system inertia -- today provided by all the kinetic energy stored in all our rotating turbines and rotors in our system -- and necessary to provide damping for system disturbances such as faults. Wind, I believe, also does not provide this if using variable speed turbines, which effectively decouple the turbine's inertia from grid frequency. The increase of these sources combined with the presumed decrease in the use of centralized resources necessitates the re-introduction of inertia...I can see this managed readily, say, by other spinning reserves but again, this is another cost that's not normally applied to discussions of higher renewable penetrations.

We aren't going to be burdened with these considerations anytime soon, in my opinion, but I would think they need to be re-engineered back in.

I can't shake the thought that large-scale renewables can't displace the building of other forms of non-intermittent capacity to meet system demand.

Wiser & Bolinger, ref. 8, p. 27, document 11 recent U.S. utility studies showing that even variable-renewable penetrations up to 31% generally cost <0.5¢/kWh to “firm” to central-plant reliability standards. The two studies that found costs up to 0.8¢ didn’t assume the sub-hourly market-clearing that most grid operators now use.

Besides it's not like these problems do not already exist and do not already have to be taken care of:

Seven German nuclear plants have failed to generate any electricity this month due to technical breakdowns. They have about half the production capacity of Germany's 17 nuclear reactors, but Germany did not suffer any power shortages.