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Even more recent events in Solar Power
November 17, 2011 6:51 PM   Subscribe

Some interesting things have recently happened in the world of solar power: Evergreen and Solyndra have gone bankrupt, panel cost has gone sub $1.00/watt, and China has vastly increased production capacities.

Before getting to the much-publicized Solyndra, let's see what happened to Evergreen. Evergreen built a hugely expensive facility in the Boston area. Certain parts of Evergreen's assets have already been auctioned off, including 7.8 megawatts of 200W to 215W panels which were purchased by SunElec, a wholesaler in Miami. These were sold off in a couple of days at 78 cents/watt, minimum quantity one pallet.

What went wrong with Evergreen? They received tax breaks from the state of MA to set up a facility there. Unfortunately, economies of scale couldn't compete with vertically integrated solar firms in China. Their string ribbon panels maxed out at a wattage density of around 130 to 135W/square meter, while current generation budget panels from China are pushing 155 to 165W/square meter.

In the past year, solar panel costs from China have dropped from $1.65/watt to sub $1.00/watt. This has driven prices down worldwide. It's now possible to buy low quantity (quantity, one!) solar panels made by Sovello for $1.04/watt from US distributors. The relative simplicity of assembling a solar panel of 60 or 72 156mm cells has lent itself to highly automated production in China. Basically, take a plastic solar module backsheet, place a series of aligned and tabbed solar cells on it, laminate with EVA, add aluminum frame and rear junction box, package the finished product.

For the electronics manufacturing industry in China this has not been difficult to scale up to very large size plants. Making a solar panel is actually quite a bit less complicated than making a basic multi layer $80 ATX motherboard for a desktop PC.

How quickly has China scaled up? Canadian Solar recently supplied the modules for the world's largest solar plant in southern Germany. The cost drops on solar PV mean that the Blythe Solar Power Project, which may cost as much as $6 billion, has recently changed plans from using concentrated (mirror-reflected, steam turbine) concentrated solar to PV. First Solar has put out a few press releases about supplying up to 1.0 gigawatts of CdTE thin-film modules for the Blythe project.

And now for Solyndra. I was recently asked:

"Tell us about why Solyndra was a terrible idea both technology and economically. I have my thoughts on the matter but would love more input from a other person in the field".

Politics aside, here's my technical opinion (as a person that works with solar) why Solyndra in general was a bad idea:

1) The weird cylindrical tube manufacturing process was very expensive both in capital equipment costs, time, and labor.

2) The relatively low power density of the individual assembled modules meant that it was only economical for very large roofs. It had a density more comparable to amorphous Si panels on glass, not 155W/square meter polycrystalline Si 60 or 72 cell modules.

3) The power rating of each module was only with a white painted roof. If you look at photos of the larger examples of Solyndra installations the roof was always painted reflective white, and this was required for any large installation. This added to installation costs and also meant that any installed solyndra system would slowly start generating less power every year as the roof got dirty. There was no practical way to pressure wash a white roof once it was covered in wired-together modules.

4) Its lunch was eaten by $1.20 to $1.50/watt poly and monocrystalline Si modules from China that anybody could buy, while Solyndra continued to only sell its modules through specially approved dealers and at mounted costs of much higher than $2.00/watt for just the modules and feet.

5) It was only suitable to one type of roof. You can mount a 60 cell aluminum framed module in almost any way - on your house, on angle mounts on top of a home depot, on the bimini top of a sailboat, vertically on the wall on the side of a telecom equipment shelter, etc.

Basically, Solyndra created a completely proprietary product that had a terribly expensive manufacturing process, and built a huge factory to scale up their technology at exactly the same time that various Chinese competitors were scaling up the mass production of 156mm polycrystalline and monocrystalline cells. Digitimes, a Taiwanese semiconductor industry trade journal reports that polycrystalline 156mm cells are now sub $0.55/watt, and monocrystalline cells are approaching the $0.60/watt figure.

Three US firms are working on thin film technologies which have the possibility of approaching the magical $1.00/watt figure and even going below it.

Ascent Solar, Global Solar and Solopower have built pilot lines which produce flexible CIS/CIGS solar modules that can be glued directly onto flat roofs. These come in rolls, with a single Global Solar module measuring 5.7 x 0.5 meters and with a wattage density of about 106W/square meter. Solopower has received a $197 million loan guarantee to build a fab in Oregon to produce their modules. They're not shipping in commercially viable quantities yet, but all three of these companies (which make a very similar product) are going to face stiff competition from the abovementioned $1.00/watt 300W solar modules from China.

On the high end: Sunpower has produced a 327W panel now commercially available which has a density of 200.5W/square meter, far exceeding anything available from China. This is produced at a fab in Malaysia, in a joint venture with AU Optronics, a major manufacturer of flat panel LCD displays. If the race to the bottom on price isn't a viable business plan, some firms have decided to compete with better technology. The Sunpower modules are particularly interesting as the positive and negative contacts for each cell are entirely on the back sides of the cells, eliminating the vertical lines seen on common solar cells. Every few percent of added efficiency is helpful.
posted by thewalrus (103 comments total) 133 users marked this as a favorite

 
Amazing and informative post. Thanks! My one other question is whether there is a simple resource for estimating annual kWh production based on orientation and azimuth, location and historic weather patterns. It seems like there should be a google maps type resource for this, does such a thing exist?
posted by meinvt at 7:03 PM on November 17, 2011


Other than things like powering remote call boxes & providing power where copper wire delivery would be unfeasible or impractical, what exactly is the overriding appeal of solar?

As far as I can tell, it's still hugely expensive (though that will certainly change) and requires so muc energy & resources to produce that the "break-even point" (where the unit has finally produced more energy than was used to manufacture it) may be undesirably distant. Also, although not the same as a greenhouse gas, I have to imagine that it would contribute (in its way) to global warming, as it basically relies on keeping more heat & energy Earthbound.

Is there a good primer (perhaps amongst the above links) that explains why solar is a preferable (or even viable) option for any kind of large scale use?
posted by ShutterBun at 7:05 PM on November 17, 2011


For a basic estimation, use PVwatts version 1 from the US DoE NREL. Give it your array size, azimuth, tilt angle and it'll estimate each month's kWh production. This takes into account historical weather data for your area and sunlight hours/day. Notice that at latitudes above 40N, production sucks in December and January. It's hard to get around that, particularly on the shortest days of the years - but that mattered a lot more when solar panels cost $3.50/watt, not $1.04/watt...
posted by thewalrus at 7:05 PM on November 17, 2011


Basic $ > all. How isn't this apparent?
$? is foisted upon others.
posted by Mblue at 7:10 PM on November 17, 2011 [1 favorite]


PVWatts version 2 is also good because it lets you select a location from a map and isn't limited to selected sites, though it is only for locations in the US.
posted by Rickalicioso at 7:11 PM on November 17, 2011 [1 favorite]


"Other than things like powering remote call boxes & providing power where copper wire delivery would be unfeasible or impractical, what exactly is the overriding appeal of solar? "

Link here that may explain why:

"It takes power to make power—even with a solar grand plan. From the mining of quartz sand to the coating with ethylene-vinyl acetate, manufacturing a photovoltaic (PV) solar cell requires energy—most often derived from the burning of fossil fuels. But a new analysis finds that even accounting for all the energy and waste involved, PV power would cut air pollution—including the greenhouse gases that cause climate change—by nearly 90 percent if it replaced fossil fuels."
posted by troll on a pony at 7:16 PM on November 17, 2011 [5 favorites]


It's now possible to buy low quantity (quantity, one!) solar panels made by Sovello for $1.04/watt from US distributors.

This link is broken. I know because I jammed my mouse on it as hard as I could because WANT WANT WANT.
posted by DU at 7:17 PM on November 17, 2011 [1 favorite]


requires so muc energy & resources to produce that the "break-even point" (where the unit has finally produced more energy than was used to manufacture it) may be undesirably distant.

Oh lord, not this ridiculous myth again.
posted by DU at 7:17 PM on November 17, 2011 [5 favorites]


DU:

Oops. It was supposed to be a link to the Sovello AGwebsite, which has the datasheets and TUV/UL certifications, but you can buy the panels for between $1.04/watt and $1.10/watt from SunElec.
posted by thewalrus at 7:18 PM on November 17, 2011 [2 favorites]


AFAIK photovoltaic solar has very low operating costs, and no emissions from the generation site. This makes it attractive against oil and natural gas which can have large fluctuations in price, and coal, which only exists because we don't price externalities properly.

Also the real technical problem that needs to be cracked is storage.
posted by Grimgrin at 7:26 PM on November 17, 2011 [3 favorites]


Off the top of my head I think the world's current energy needs are one ten thousandth of the energy the earth receives from the sun. Over the last 30 years the efficiency of solar panels has doubled about every two years. If that trend continued over the next 16 years the world could run on solar power. There are a lot of empty deserts which could be the power stations of the future, as well as greatly reducing the problem of carbon emissions from fossil fuels. I'm not saying this will happen, I am saying it could. That's why it's important ShutterBun.
posted by joannemullen at 7:29 PM on November 17, 2011 [4 favorites]


I have a gable roof whose south-facing side is approximately 20' x 50'. Unfortunately, trees to the west shade half of it from about 3:30 onwards in the summer. Slope is 4:12. Hm. I'd be excited to put solar up there. Maybe that day will arrive sooner than I thought.
posted by maxwelton at 7:32 PM on November 17, 2011


Storage is a big problem. Lead acid batteries suck. Pumped water energy storage is only viable in a few places with the right geography. Liquid Metal Batteries seem promising but operate at very high temperatures.

In off grid locations where it would cost anywhere from $25,000 to $300,000 to extend grid power to a remote site, spending $4500 on a bank of lead acid batteries and replacing them every six years is not so bad...
posted by thewalrus at 7:35 PM on November 17, 2011


what exactly is the overriding appeal of solar?

From the perspective of the work I do [the lower income market in Sub Sahara] - there are two key drivers for what is happening here and one interesting finding from the field, which may or may not have implications for Chinese manufacturers, further down the line, time will tell.

1. A country like Rwanda, say, is rapidly bootstrapping itself in order to achieve its goals of becoming the next 'Singapore' - however, only 5% of population is on the grid and the rest of teh country is mountainous. How do you rapidly deploy access to energy for light, first and then heat?

2. Given that China has already perceived the huge untapped opportunity in Sub Sahara, similar to that of the mobile phone [in that, the vacuum in existing infrastructure and the need for speed imply a leapfrogging over existing technology], the motive power exists for the massive push for the most affordable devices. The market is such.

However, and interestingly, I walked into an electrical shop in a tiny market town in rural Kenya a couple of weeks ago just to talk about solar (in preparation for a response to an RFP by a consumer oriented brand) and it seems that its not purchased by brand, and though price is indeed important, its German manufacture that is sought after - for quality and performance. After all, once you hook your entire new home up to this system, the last thing you want to do is buy cheap Chinese and have to replace it in a couple of years in the harsh environment.

The Germans have definitely made it in and established themselves in this relatively mature market so it will be interesting to see how it plays out at the household level with China. On the other hand, good brands, if they establish themselves by name, may not have the challenge of overcoming the "Chinese mfr" issue - even Nokias and iPhones are made in China these days.

[For context, you can get a basic starter kit for under a $100 and the worst you can do for a full home set up [lights, fan, TV, Fridge etc] would be $400]
posted by infini at 7:38 PM on November 17, 2011 [9 favorites]


Oh and fantastic and timely post, thewalrus
posted by infini at 7:41 PM on November 17, 2011 [1 favorite]


Not all the Future of Solar is small, individual installations. There's a big Solar Farm (1500 acres within an 8-square-mile protected area) getting built not far from me, even though the company building it, SunPower, is on shaky ground. Expected to start supplying power in a year, and when it's fully running in 2014, it should power most of the county of San Luis Obispo (100,000 households) or its equivalent, through the wires of existing power company PG&E (the same people who run the Diablo Canyon Nuclear Power Plant that worries many of us 'round here). Not sure who's specifically making the panels.
posted by oneswellfoop at 7:48 PM on November 17, 2011


oneswellfoop: Sunpower is providing the modules (aka panels) and probably sourcing the inverters and balance of system components (mounting, wiring, combiners, disconnects, SCADA), the rest of the article says:

NRG Energy of Princeton, N.J., assumed ownership of the project Sept. 30, although SunPower will build the plant and operate it for the first two years after completion. San Francisco-based construction giant Bechtel is the project’s building contractor.
posted by thewalrus at 7:53 PM on November 17, 2011


"Over the last 30 years the efficiency of solar panels has doubled about every two years. If that trend continued over the next 16 years the world could run on solar power. "

That's not going to happen. The doubling, I mean.

As I understand it, there is a practical limit to squeezing the juice out of sunlight, and much of the heavy lifting has happened already in terms of getting more efficient conversion. If we get 20% better efficiency with commodity solar over the next 30 years, that would be awesome.
posted by Glomar response at 8:06 PM on November 17, 2011


Currently, if you are on the grid, storage is not an issue. You sell un-needed energy back to the utility. This will not always be a solution, but it works for now in many places.
posted by Mei's lost sandal at 8:13 PM on November 17, 2011 [2 favorites]


because WANT WANT WANT

The Miami retailer mentioned in the FPP - Sun Electronics - doesn't just sell panels by the pallet. They have a warehouse you can walk into and buy individual panels - i picked up 60 and 90 watt 12 volt panels while I was down there this summer. Those particular units happened to be a tad over $2/watt at the time but it was still much, much less than they would have cost in Ontario. I've done a lot of eBay trolling over the years and as far as I can tell they've got the cheapest prices.
posted by CynicalKnight at 8:20 PM on November 17, 2011 [2 favorites]


Has anyone worked on floating solar power plants? The impression I get is that replacing all the energy consumption in the U.S. (including gas stations, etc., if electric vehicles become widespread) would require a significant fraction of the land in the country, at least a few states worth. It seems like, if the engineering issues could be worked out, it might be practical to site at least some of the the plants offshore.
posted by XMLicious at 8:23 PM on November 17, 2011


Is it possible to set up a grid-tie system where you can later buy and add more panels to it yourself, without getting anyone else involved?

I'd like a grid-tie system, but I'm put off by the talk of inspectors and the like. Can you get the inverter bit that ties to the grid installed and inspected and stuff, and then just do whatever you like, whenever you like, with adding and removing panels from it?
posted by -harlequin- at 8:24 PM on November 17, 2011


would require a significant fraction of the land in the country, at least a few states worth.

If you're east coast, ok. If you're southwest... less than one :-)
posted by -harlequin- at 8:26 PM on November 17, 2011


Solar panels don't have to operate on Earth. The insolation received by our planet is a very small portion of the total output of the Sun. The real "break-even point" will come when we can send solar panels up into space for less energy than they can send back to us via power beam transmission.
posted by xigxag at 8:28 PM on November 17, 2011


Has anyone worked on floating solar power plants?

IANAS but this is a bad idea on face for a number of reasons. 1) water and electricity don't mix well, and 2) blocking sunlight from reaching the ocean has effects that hasn't been studied yet I'm sure. At the very least it would create a dead-zone underneath the panels.
posted by gen at 8:29 PM on November 17, 2011 [1 favorite]


Over the last 30 years the efficiency of solar panels has doubled about every two years. If that trend continued over the next 16 years the world could run on solar power.

Like Glomar response already mentioned, this is not feasible. I can't find it right now but there's a great blog post floating around out there explaining that 30% efficiency is probably at or near the physical limitations of the technology.
posted by odinsdream at 8:37 PM on November 17, 2011


*And the Puppeteer hid both his heads when he heard xigxag*
posted by infini at 8:38 PM on November 17, 2011 [5 favorites]


floating solar is really unnecessary, when a recent study has shown that thorough use of rooftop solar on all buildings could meet half of new york city's electrical demands.

The US has a lot of unused roof area...
posted by thewalrus at 8:38 PM on November 17, 2011


"Over the last 30 years the efficiency of solar panels has doubled about every two years. If that trend continued over the next 16 years the world could run on solar power. "

Not really. Prices have dropped dramatically for photovoltaics. But even the best polycrystalline and monocrystalline cells seem to be stuck in the range of 15.8% to 20.5% efficiency, which we're not going to get past without some very novel nano/micro structures on the top surface of crystalline Si cells. Let's not even talk about 30% efficient triple junction gallium arsenide cells, which exist, but are so expensive they're only used on spacecraft.

It's better to look at $/watt, $/kWh, lifetime kWh produced vs. capital equipment cost, and density of watts/square meter (eg: can you fit enough modules on top of your house to power everything?). If the lifetime kWh cost for you to buy and run a gridtied solar system is 16 cents a kWh and your grid-supplied power costs 21 cents/kWh during peak hours, that's the important figure to know.
posted by thewalrus at 8:41 PM on November 17, 2011 [2 favorites]


I spoke with someone in the industry about the decreasing cost of solar. He said this is happening because China is dumping. However once the dumping is over, prices will stabilize or go back up. So a lot of planning is being done now with the assumption of falling prices that may not actually happen.
posted by stbalbach at 8:47 PM on November 17, 2011


I didn't realise that the company developing those stupid solar tubes was Solyndra. Things make more sense now.
posted by -harlequin- at 8:52 PM on November 17, 2011


Oh lord, not this ridiculous myth again.

Hey, it was an honest question. I think the "myth" is that a solar panel will *never* break even. From a bit of searching, it looks like the breakeven point depends a lot on what kind of solar technology we're talking about. Something like 1 year for one kind of panel, but up to 10 years for other kinds. I deliberately used the phrase "undesirably distant" to address the latter situation.

Obviously, things are moving in the right direction, but insofar as solar power is still more or less a sales pitch, it would be a good idea to highlight this kind of stuff for those of us in the "is it worth it? (seriously, we want to know!) crowd.
posted by ShutterBun at 8:56 PM on November 17, 2011


Is it possible to set up a grid-tie system where you can later buy and add more panels to it yourself, without getting anyone else involved?

A relative has a PV grid-intertie system (used to be off the grid, until the grid extended out to where they live). I don't think the inspectors even look at the DC side of the system. Presumably if we added enough panels to need a larger inverter, they'd want to re-inspect that, but other than that what the DC side is fed with is not their concern. (Fire department or insurance inspectors might care, I guess. I'm just talking about the power utility guys.)

Rules vary though so your mileage will as well. Some utilities are hostile towards interties even if they're required to allow them; some are quite helpful; some are not intentionally difficult but don't really know how to handle you.
posted by hattifattener at 8:56 PM on November 17, 2011


would require a significant fraction of the land in the country, at least a few states worth.

If every damn huge flat roofed building--schools, apartments, and especially factories, warehouses, and big box stores would put up solar, we could see a significant change in how much power we use during the daylight hours. I'm sure there's a state's worth of acreage right there.
posted by BlueHorse at 8:58 PM on November 17, 2011


If you're east coast, ok. If you're southwest... less than one :-)

Are you sure? Just doing some quick calculations with Googled numbers I was getting 190 million acres, a bit less than a tenth of the total land area of the country, based upon the power consumption in 1990 (but with 2011 figures on a power plant.) My numbers could easily have been off but my impression has always been approximately that.

...blocking sunlight from reaching the ocean has effects that hasn't been studied yet I'm sure. At the very least it would create a dead-zone underneath the panels.

Wouldn't there be the same problems with such large plants on land? I was figuring you'd put as far out over the deep sea as possible where there's already no light at all reaching the ocean floor. Or, for that matter, you could put it over one of the dead zones we've already created.

As far as water and electricity, that kind of comes under "if the engineering issues could be worked out", but there are already working tidal generation systems so it's not so beyond the pale.

floating solar is really unnecessary, when a recent study has shown that thorough use of rooftop solar on all buildings could meet half of new york city's electrical demands.

The link doesn't work but that seems kind of surprising... wouldn't that mean that on average, covering one building's roof with solar panels would supply far more than that building consumes? (Given that the high-demand outliers would be leaning on everyone else.) The houses I've seen powered by rooftop solar are usually single-family dwellings that are constructed to be super-power-economizing, requiring minimal heating and air conditioning, etc., which doesn't describe most of the buildings I've seen in NYC.

(Also, I'm talking about all power consumption, not just electricity, so replacing all the gasoline and heating oil and everything else to get to the "replacing fossil fuels" scenario.)
posted by XMLicious at 9:02 PM on November 17, 2011


Very interesting, they've linked this scheme to having at least 60% of the components be made in the EU

Solar Subsidy in Europe to Stimulate Demand; Prices of Products with High Conversion Efficiency Remain High
posted by infini at 9:03 PM on November 17, 2011


we could see a significant change in how much power we use during the daylight hours.

Power use would remain the same. Only the source of the power would change.

And not to get all "fear of a black planet" about it, but can anyone point to any studies related to how lowering the Earth's albedo and generally increasing the amount of available heat & energy might (or might not) relate to our current temperature/climate problems?

(I'm betting it's better than burning oil to spin turbines, but by how much?)
posted by ShutterBun at 9:04 PM on November 17, 2011


If the price we paid for energy reflected its actual costs, without all the oil and coal subsidies, tax breaks, not to mention multi-trillion dollar wars fought in areas that we otherwise wouldn't give a rats.... care about, we would be conserving a lot more without anyone telling us to (I'd certainly drive a lot less if gas was over $6/gallon, and would be more likely to turn off my lights if my electrical bill quadrupled.

And solar power, at its present price, would probably be considered a bargain.
posted by eye of newt at 9:05 PM on November 17, 2011


Something like 1 year for one kind of panel, but up to 10 years for other kinds. I deliberately used the phrase "undesirably distant" to address the latter situation.

OTOH It might take ten years of design and construction before a hydro-electric dam even starts producing it's first watt, let alone paid back its construction and operation costs. I'd guess fifteen years at least to design and build a nuclear power plant before it can be started?
I suspect that for some applications, solar could be installed and pay itself back before the competition is even operational :)
posted by -harlequin- at 9:05 PM on November 17, 2011


The houses I've seen powered by rooftop solar are usually single-family dwellings that are constructed to be super-power-economizing,

OTOH they also generally have solar panels on only a small fraction of their available rooftop area.
posted by -harlequin- at 9:08 PM on November 17, 2011


Traditional photovoltaic solar power is not exactly a profitable business, anyone who says otherwise doesn't understand business. Photovoltaics can be compared to the DRAM computer memory market. Market participants are unable to differentiate and must only compete on price (they do not have a "wide moat" to use a term coined by Warren Buffett). That is not to say that it's a bad investment (and it definitely has a high chance of turning out to be an excellent investment from a larger global/aggregate measure), it's just not exceedingly profitable for an individual firm.

Photovoltaics are also seeing a long-run Moore's Law in effect where the cost per watt is being driven down at a systematic rate. We're at a point where solar is almost cost competitive with retail power prices without substantial government subsidies in really sunny places. It will be interesting whether photovoltaics continue to follow other silicon-based technologies such as DRAM and continue their steady Moore's Law reduction in cost, albiet at a slower annual rate than memory/processing. It is theoretically possible that an annual 7% reduction in $/Watt prices per year may cause solar to become the most viable alternative energy source. Solar may prove to be huge potential economic threat to oil/fossil fuels, 10 years from now it may be close enough to retail price parity it's only one step function technological discovery away from seriously threatening the profitability of high-fixed-cost oil producers such as deep-sea oil and tar sands.
posted by amuseDetachment at 9:08 PM on November 17, 2011


There's a bar/pizza joint here in Tucson that's 100% solar powered..they installed a nice array of panels on one side of the parking lot (which also provides shaded parking) and run the AC with the screen door open..all the while selling extra power back to the power company.

It's rad.
posted by chronkite at 9:10 PM on November 17, 2011


100% solar powered.

Even the ovens? The company that installed their system says it puts out 12,000kWh per month, which is FAR less than a typical restaurant apparently uses.
posted by ShutterBun at 9:28 PM on November 17, 2011 [2 favorites]


According to this the energy production in the US last year was about 4.2 TWh, so lets see how much solar would be needed to generate that. Of course the sun doesn't shine 24hrs a day, so you can't have 100% solar powered country unless we run a huge cable half way around the planet ... ok back to the first problem.

4.2x10^15 Whr/Year needed

Insolation for 1m^2 in average northern climes about 4x10^3 W/m^2/day. This is pretty conservative.

Assume about 15% efficiency.

So 4x10^3 x 365 days x 15% efficency = 2.19x10^5 Whr/m^2/Year

So 4.2x10^15 Whr/Year / 2.19x10^5 Whr/m^2/Year = 1.94x10^10 m^2

Which is a square sqrt(1.94x10^10) / 1000 = 139.3 km on a side

Or about about 87 miles on a side.

So fine a patch of New Mexico desert not quite 100 x 100 miles and pave it with solar panels. Where do I sign up for that project?
posted by Long Way To Go at 9:29 PM on November 17, 2011 [4 favorites]


I can't wait until the local utility plugs my PV array into the grid and I can score some of that sweet sweet 53c/KwH electric generator action.
posted by Wolof at 9:29 PM on November 17, 2011


gen: "...blocking sunlight from reaching the ocean has effects that hasn't been studied yet I'm sure. At the very least it would create a dead-zone underneath the panels."
XMLicious: "Wouldn't there be the same problems with such large plants on land?"

Yup, pretty much. 95+% of the bio-geo-chemical processes that keep Earth habitable are solar-driven. Even - in some ways especially - in deserts. And that's just the ones we understand or can explain reasonably. My personal opinion is that we'd have to consider things very carefully before reducing the insolation falling on allegedly "empty" desert.

For instance, I'm aware of people currently studying the contribution of microbial desert life to atmospheric gas composition - both "good", in terms of O2 production & nutrient cycling, and "bad" in terms of CO2, CH4, and other GG production. We might want to hold off shading huge areas of desert until we understand what'll happen if we do…

"I was figuring you'd put as far out over the deep sea as possible where there's already no light at all reaching the ocean floor. Or, for that matter, you could put it over one of the dead zones we've already created."

Most of the biological processes in the sea happen in the first few metres of water - the ocean floor really doesn't come into it. And the "dead zones" are only relatively dead compared to the rest of the sea - there's likely more biomass in the epi- & mesopelagic layers of a "dead zone" than there is in the equivalent desert area.
posted by Pinback at 9:35 PM on November 17, 2011 [2 favorites]


Working from Long Way to Go's rough calculations above,

Rather than blocking anything (ocean or desert), I'm going to take a totally unscientific guess and declare that the US has more than 19600 square kilometers of roofs. Distributed generation solves some of the problem of how to transport the electricity across the nation from a theoretical 140 x 140 km patch of New Mexico desert paved with solar panels.
posted by thewalrus at 9:39 PM on November 17, 2011


energy production in the US last year was about 4.2 TWh

Err...didn't it say 4200 TWh?
posted by ShutterBun at 9:41 PM on November 17, 2011


Why put solar panels in the desert? We've already covered up lots of land mass with buildings and parking lots. Just put the panels over these, and you are not covering natural environments, and are generating the power where it is getting used.

thewalrus just beat me to the argument, but he forgot parking lots so I'm still posting.
posted by eye of newt at 9:43 PM on November 17, 2011


Can Solar Cells Ever Recapture the Energy Invested in their Manufacture?

YES! Even though this article uses pretty old data to prove it.

More recent article (2000):

The use of photovoltaic systems on a large scale in order to reduce fossil fuel consumption and greenhouse gas emissions requires that the energy associated with the construction, operation and decommissioning of PV systems be small compared with energy production during the system lifetime. That is, the energy payback time should be short. The energy intensity and cost of PV systems are closely related. At present the energy payback time for PV systems is in the range 8 to 11 years, compared with typical system lifetimes of around 30 years. About 60% of the embodied energy is due to the silicon wafers. As the PV industry reduces production costs and moves to the use of thin film solar cells the energy payback time will decline to about two years.
posted by Long Way To Go at 9:43 PM on November 17, 2011 [1 favorite]


Err...didn't it say 4200 TWh?

Whoops, so it did. But I used 4.2x10^15 in the calc which is 4200 TWh.
posted by Long Way To Go at 9:45 PM on November 17, 2011


Yep, I was gonna come back and apologize, but your scientific notation skillz are much quicker than mine ;-)
posted by ShutterBun at 9:46 PM on November 17, 2011


1.94×1010 m2

According to a quick google, there's about 1.85×1010 m2 of rooftop area in the US currently. (And 1.6×1011 m2 of paved road surface.)
posted by hattifattener at 9:48 PM on November 17, 2011 [2 favorites]


Why put solar panels in the desert? We've already covered up lots of land mass with buildings and parking lots.

Absolutely!

It is cheaper on a $/W basis to build huge solar plants, which lend themselves to nice flat open land with no shading. However there are additional costs of transporting the energy to its users. I think everybody in the solar industry realizes that the optimal solution is a mix of residential/commercial buildings and utility scale installs in locations where it makes sense such as marginal but disturbed agricultural/industrial land. Nobody seriously plans to pave pristine wilderness.

My point was to give people an idea of how much area is needed and show it's quite attainable.
posted by Long Way To Go at 9:54 PM on November 17, 2011


It's easy to agree that if every structure was covered with high efficiency PV on the roof, we could meet our energy demands, but we need some kind of mass scale storage system for when the sun goes down. Several dozen massive liquid metal batteries installed in each major city, connected to the grid? Pumped storage water hydroelectric systems that pump water uphill during the daytime when solar is plentiful, and run it back through turbines at night?

Current battery technology just doesn't work on a large scale, when you look at any combination of $/Wh stored, Wh per kilogram, Wh per litre of volume occupied by the battery, etc.
posted by thewalrus at 10:03 PM on November 17, 2011


The impression I get is that replacing all the energy consumption in the U.S. (including gas stations, etc., if electric vehicles become widespread) would require a significant fraction of the land in the country, at least a few states worth.

Here is how I answer questions like this.

1. Search for "solar power efficiency". This seems to be the best result. Best seems around 14.5%, so let's go with 10% for our calculations.

2. Search for "incident solar energy". This link, which appears to be lecture notes from a class, is actually working through the calculations I want to do. I follow along with the math, and their figure of 180KWH per day in the winter with 100 m^2 of collectors seems reasonable. This assumes 6 hours of sunlight per day.

So, assuming 10% efficiency, that means a 100m^2 array should be able to do 18KWH per day.

3. Search for "us electricity consumption". I'm going to go with 3.741 trillion kWh for all of 2009.

4. I like to use google as a calculator for stuff like this, so I put "(3.741 trillion kWh / 365) / 18 kWh" into google and come up with 569,406,393. Now I put "569406393 * 100 m^2 in km^2" (cause I'm lazy) in google and come up with about 57,000 km^2.

According to wikipedia, the US is 9,158,960 km^2. So at 10% efficiency, we would need to cover 0.6% of the country in solar panels in order to provide enough electricity for the US in winter.

Obviously that's not the exact number. There's transmission and storage losses, and weather gets in the way. New Jersey is about 20,000 km^2, so it would take about three New Jerseies worth of solar panels to provide for the electrical needs of the US.

That's not small, but it's also not outlandish. For comparison's sake, there are an estimated 100 million to 2 billion parking spaces in the US. Assuming a low but reasonable figure of 500 million parking spaces and 15 m^2 per parking space, there are 7500 km^2 of parking spaces in the US. So that's about 10% of the way there.

And of course, while doing that I stumble upon this much better analysis.
posted by heathkit at 10:05 PM on November 17, 2011 [3 favorites]


Hrmmm...a lot of these studies seem to do a lot of rounding off, out of necessity, to make the very very large numbers easier to digest, but this site says that "a one square meter solar electric panel with an efficiency of 15 percent would produce about one kilowatt-hour of electricity per day in Arizona."

That means that in order to provide for the U.S. we'd need a little over 4 trillion square meters. (4200 Terawats being 4.2 Quadrillion watts) Or 4 billion square kilometers. Or a giant square over 63,000 kilometers per side.

I'm guessing one of us has misplaced a decimal point or two. I suspect me, but feel free to point out where I went wrong.
posted by ShutterBun at 10:08 PM on November 17, 2011


We need some kind of mass scale storage system for when the sun goes down--thewalrus

Do we? I thought most of our energy usage is during the day and much of our electricity generating capability goes idle at night.

That's why in many places when your house is empty and you are at work, you can sell your PV panel power back to the power company, and you can use that savings to power your house at night.

The power company becomes your 'storage'. It is really more of a lend/return system. You lend them the power when they need it the most, then take it back when they have plenty to spare.
posted by eye of newt at 10:09 PM on November 17, 2011


(oh, I think I just spotted it. Forgot to convert watts into kilowatts from the get-go, I think) Don't mind me.
posted by ShutterBun at 10:10 PM on November 17, 2011


I think rather that looking at it in the perspective of covering three new jerseys in solar panels, it's worth looking at it by individual structures. First, calculate for the square meters of roof space available, how many kWh can you generate in one month if covered in high-efficiency PV?

Second, how many kWh does the structure (whether warehouse, home, office, whatever) currently use in a month? How much can this be improved through insulation and energy efficiency modifications (100% CFL / White LED lightbulbs, turning off the lights at night, etc)?

Third, can the solar array generate more cumulative kWh in one month than the structure is currently drawing from the grid?
posted by thewalrus at 10:13 PM on November 17, 2011


Why limit it just to the square footage of roof space? According to this , Fibonacci and trees have already come up with a better arrangement. (though I suppose one would have to do some careful planning before installing an array, due to shadows & whatnot)
posted by ShutterBun at 10:18 PM on November 17, 2011 [1 favorite]


How much can this be improved through insulation and energy efficiency modifications (100% CFL / White LED lightbulbs, turning off the lights at night, etc)?

I did notice that by default, all the electrical shops selling the requirements for home installation, offered a variety of energy saver bulbs. Apparently what kills the system is ironing.
posted by infini at 10:18 PM on November 17, 2011


< proudly writes: "I'm Part of the Solution" on my wrinkly t-shirt
posted by ShutterBun at 10:27 PM on November 17, 2011 [2 favorites]


Here's a home built battery backup system. It's installed between the maker's breaker box and his connection to the power grid. He sets his battery system to charge at night (when power is cheap) and power his house during the day (when power is expensive).

I think the future of solar energy is decentralized. Every structure should have a system like this combined with some kind of on site generation - solar, wind, or geothermal, whatever makes sense. The local battery system acts like a buffer, buying supplemental energy from the grid as needed and selling back to the grid when there's a surplus.

Such a system could be supplemented with a few centralized power stations that only sell to the grid. Still, I think it's important to recognize that transmission loss is an important factor in our energy consumption. We could save tremendous amounts of energy by transmitting less and generating more closer to the point of consumption.
posted by heathkit at 10:27 PM on November 17, 2011


Fibonacci and trees

I think I remember posting in that thread - the main problem being that modern high efficiency solar panels are large, and catch the wind like sails. They're either 1.65 x 1.0 meters or 2.0 x 1.0 meters in size. Hanging a lot of them on a tree like structure would require a very significantly sized steel monopole (as currently used for cellular antenna base station sites), and a serious concrete foundation for it.

The mounting cost for several hundred 1.65 x 1.0 meter panels on a flat roof is already non negligible, if you wanted to hang them out in the wind on tree like structures, the mounting and erecting the mounting would probably cost more than the solar panels themselves.
posted by thewalrus at 10:29 PM on November 17, 2011


He sets his battery system to charge at night (when power is cheap) and power his house during the day (when power is expensive).

It's my understanding that "Time of Usage" metering for us residential folks is exceedingly rare though, no?
posted by ShutterBun at 10:31 PM on November 17, 2011


Long Way To Go, for whatever reason if you take the area covered by the PV power plants listed on Wikipedia and divide that by the amount of power produced yearly you get an output per square meter less than a tenth of the figure you're using there. Also, you started from domestic electricity production rather than total power consumption from fossil fuels which I'm pretty sure is substantially greater than just electrical production. (Not to mention that domestic production is leaving out everything we get from Canada... I'm not sure on the actual amounts there but I believe that NYC gets quite a bit of its power and water from Quebec and I would assume that it's going to be a similar situation with Detroit, Seattle, and other metropolises near the border.)

Yeah, looking at heathkit taking the same tack too as well as the analysis he links to, I really don't get why people approach this via some theoretical model involving the amount of energy in sunlight hitting the Earth's surface and the output of the surface area of a single solar panel. I mean it's not like it's 1970, we have actual large-scale optimized solar power plants now.

I think that solar power is a big part of our energy future, I just think that no one is served by fudging numbers by a factor of ten or sweeping the major engineering challenges under the carpet... storage, as people point out, is a big hurdle.

I like the point about parking lots and it occurs to me that we've got even more area in streets and highways, which also are already denuded of any ecosystem that might be harmed by blocking the sun... if we could roof over highways the way they do when they rig up parking lots for power generation that would get us a whole lotta acerage. (Though as thewalrus points out, wind is another big difficulty.)
posted by XMLicious at 10:36 PM on November 17, 2011


I'm guessing one of us has misplaced a decimal point or two. I suspect me, but feel free to point out where I went wrong.

Given an average of 10^3 WHr/m^2/day (Arizona is sunny!)

There are 365 days in a year. So that's 3.65x10^5 Whr/m^2/Year

So its 4.2x10^15 Whr/Year divided by 3.65x10^5 which is 1.15x10^10 m^2

Not to get confused converting between m^2 and km^2 (which is actually 1 million square meters). The square root of 1.15x10^10 m^2 is 1.07x10^5 m which is 1.07x10^2 km or simply 107km.

So a square 107 km (67 miles) on a side. Slightly better than my first calculation because of the stronger insolation available in Arizona.
posted by Long Way To Go at 10:38 PM on November 17, 2011


It's my understanding that "Time of Usage" metering for us residential folks is exceedingly rare though, no?--ShutterBun

It's becoming the standard with PG&E, which covers the northern 2/3 of California.
posted by eye of newt at 10:44 PM on November 17, 2011


I really don't get why people approach this via some theoretical model involving the amount of energy in sunlight hitting the Earth's surface and the output of the surface area of a single solar panel. I mean it's not like it's 1970, we have actual large-scale optimized solar power plants now.

That's reasonable, however it wasn't the point I was trying to make. I simply wanted to answer the misconception that you had to cover whole states (I mean proper states like we have out west) with solar panels to have a meaningful impact. You simply don't.

Of course real utility scale plants need space between the panels and have densities (square meters of panel per square meter of land) far less than unity. But the point was that is the area of solar panels needed, not the area of land. Expressing it as an area in square miles just makes it easier for people to grasp.
posted by Long Way To Go at 10:46 PM on November 17, 2011


Time of Usage is also standard if you have a residential solar system in California. It's what make it economic. "Sell" expensive peak time units to the utility on sunny summer days and for the rest of the time use cheap night and winter units from the utility paid for by those expensive ones.
posted by Long Way To Go at 10:48 PM on November 17, 2011


"Sell" expensive peak time units to the utility on sunny summer days and for the rest of the time use cheap night and winter units from the utility paid for by those expensive ones.

These patterns are also used by utilities to plan brownouts and rolling blackouts as they manage with limited power supply and infrastructural challenges.
posted by infini at 11:02 PM on November 17, 2011


Yeah, what Long Way to Go said. I generally do these calculations as pessimistically as possible, just to drive home the point that land use is not the limiting factor when it comes to solar power generation. If we could, for example, produce solar panels that were only 5% efficient but cost 1/10th as much as traditional panels, I think that would make solar an even more viable energy strategy.

Also, just to address it, sources I've seen (mostly wikipedia) indicate that 40% of our energy consumption is electricity. So if you want to talk about converting all energy production to solar, including fossil fuels, just double my stated figures (ie, 6 New Jerseies or a third of a New Mexico). And keep in mind all my figures assume 10% efficient panels and winter days. I don't work total energy consumption into my figures, though, because the numbers get fuzzier - I don't know how to compare efficiencies between gas and electric vehicles if you consider impacts on power transmission, battery charging efficiency, etc.

There's 140,000 km^2 of farmland in the US Conservation Reserve Program (ie, farmland that the federal government pays farmers to convert to vegetative cover to reduce ecological damage). An equivalent area of land could supply all of the US's electrical needs (and potentially transportation needs if we switched to electric vehicles).
posted by heathkit at 11:10 PM on November 17, 2011


The power company becomes your 'storage'.

That works for an individual today, but it obviously doesn't work if most of the grid is solar.
posted by hattifattener at 11:22 PM on November 17, 2011


The power company becomes your 'storage'.

That works for an individual today, but it obviously doesn't work if most of the grid is solar.
--hattifattener

This will pit me against the dreamers, but I consider the idea of most of the grid being solar as so far-fetched that I consider it a strawman argument. I'd be happy with 10%.
posted by eye of newt at 11:28 PM on November 17, 2011


My one other question is whether there is a simple resource for estimating annual kWh production based on orientation and azimuth, location and historic weather patterns.

FWIW...i read an article recentlly that i found interesting (engadget?) about a prototype solar panel mount (there was a pic IIRC) in which a smaller series of panels was mounted in an arrangement similar to the leaves on a tree (as opposed to a (standard) static south-facing mount or a (vastly more expensive) motorized sun-tracking mount)...the result? 140% more power than a standard static mount. (of the same total panel area)
posted by sexyrobot at 11:42 PM on November 17, 2011


There's 140,000 km^2 of farmland in the US Conservation Reserve Program (ie, farmland that the federal government pays farmers to convert to vegetative cover to reduce ecological damage). An equivalent area of land could supply all of the US's electrical needs (and potentially transportation needs if we switched to electric vehicles).

That's roughly the entire state of Iowa, just to put things in perspective.
posted by ShutterBun at 11:42 PM on November 17, 2011


That works for an individual today, but it obviously doesn't work if most of the grid is solar.

Wouldn't it be great if that were a problem we had to solve some day?
posted by Mars Saxman at 12:02 AM on November 18, 2011 [3 favorites]


Well, heathkit, I threaded back through the math and it appears that the figure you're using for power production per square meter is only twice what I got working from the power plant numbers, so in trying to track down the reason we have results diverging by more than a factor of two it looks like the culprit is our figures for total power use.

I worked off of the value given on this page of a total U.S. power consumption in 1990 of 86.6 × 109 gigajoules.

Normalized that's 8.66 × 1010 GJ of course. When I convert the 2009 value for electricity production you used, 3.741 trillion kWh, I'm getting about 1.35 × 1010 GJ.

So that comparison would give the total energy usage in 1990 as about six and a half times the electricity-only consumption in 2009, which is why I'm coming up with lots more New Jerseys than you. Does it look like I did that right, and that the primary difference is our sources?

If so one of them could be inaccurate or electricity being 40 percent of total power consumption wrong, though that's about what I thought it was too.
posted by XMLicious at 12:21 AM on November 18, 2011


> I can't find it right now but there's a great blog post floating around out there explaining that 30% efficiency is probably at or near the physical limitations of the technology

Don’t Be a PV Efficiency Snob
posted by Bangaioh at 12:53 AM on November 18, 2011 [3 favorites]


I wouldn't forget about Nanosolar yet. They may have been having some corporate issues but their technology is something special.
posted by cman at 1:18 AM on November 18, 2011


Bangaioh, that's a great link.
posted by smoke at 3:02 AM on November 18, 2011


Storage is a big problem.


Cable companies and other telcos have been using flywheel storage as UPS's at local switching stations for more than a decade, now. I'd think it would be ideal for small and medium solar applications.
posted by Slap*Happy at 4:23 AM on November 18, 2011 [2 favorites]


The houses I've seen powered by rooftop solar are usually single-family dwellings that are constructed to be super-power-economizing, requiring minimal heating and air conditioning, etc.

My 5.5 kW array uses less than half of my roof. (OK, it's most of the South-facing half, but if the roof were flat, I could have more panels.) This is in Massachusetts, and it produces more power than I use. My house was not built to be super efficient; it was built to 2005 standard practices in NE. I had already put in almost all CFW lightbulbs, but anyone can do that. The AC puts my energy consumption beyond what I generate, but only when it's on. When it goes off, the balance goes back to a surplus. During the brief period between when the utility installed the net meter and when they let me turn on the solar system,* I used 1500 kWh of their power. A year later, the meter shows about 400 kWh, so I have generated 1100 more kWh than I used. Heating is gas, so it's not much of a factor in the electricity. Gas is currently the big utility cost; it's $90 a month. I plan to get an electric dryer when the gas one wears out.

The installers estimated that the payback time for my system is 7 years, but that looks a little conservative to me. (That's payback of my $ costs, not of the energy costs to produce the panels.)


* Yes, I can turn the solar system on and off. Don't mess with me.
posted by Kirth Gerson at 4:59 AM on November 18, 2011 [7 favorites]


Solar is a real business. Solar cell production will be worse than making DRAM. The US should focus on generating solar energy and advancing technology. Let someone else invest capital in the Fabs.
posted by JPD at 5:46 AM on November 18, 2011


Don’t Be a PV Efficiency Snob

Yes! That's the one - thanks Bangaioh.
posted by odinsdream at 6:48 AM on November 18, 2011


These PVwatts sites linked above are really neat but how does one use that data to figure out how much power a system like this would generate?
posted by VTX at 6:49 AM on November 18, 2011


Solar is a real business.

The sample document linked is totally worth a look.

I expect, like the way mobile platform payment mechanisms and other innovative solutions emerged in developing markets first to fill the gap in the inadequate infrastructure, the same or similar is beginning happen with solar solutions and other renewables.


on preview, I'm hesitating over pushing publish, why increase the competition?
posted by infini at 6:50 AM on November 18, 2011 [2 favorites]


> how does one use that data to figure out how much power a system like this would generate?

It's got a DC rating of 3.22 kW (= 46 * 70). Choose you location, and plug that number in to PvWatts. For example, in Topeka, KS, that array might generate 4511 kWh/year.

Note that your price there doesn't include racking or installation.
posted by scruss at 7:12 AM on November 18, 2011


I know an engineer in Holland who recently installed solar on his house. He said his main motivation was it endeared him to his tree hugging hippie children, because it is going to take thirty years for the investment to pay out at current power company prices. I don't know anybody going solar in my neighborhood; the only application I see routinely is for things like the school zone temporary twenty-mile-per-hour-speed-limit-flashing signs.
posted by bukvich at 7:18 AM on November 18, 2011


Cable companies and other telcos have been using flywheel storage as UPS's at local switching stations for more than a decade, now. I'd think it would be ideal for small and medium solar applications.

Yeah, flywheel batteries seem like the best bet to me with long life, low maintenance, and high power density. It's still a big infrastructure investment that we haven't had so far but fortunately it's of benefit to wind and every other sort of power generation too. If I had a bank of flywheel batteries at my house here in New England the storm outages during the last month would have been considerably less annoying.

That reminds me, as an inspiring story: I went to visit a friend of mine who is cloistered in a monastery in southern Massachusetts. The place is mostly self-contained, with a fairly extensive farm complex. The first sight I was greeted to as I approached the address was a hundred-foot-tall wind turbine poking up over the trees. (Though I don't know if it supplies all of the power they use.)

Kirth Gerson, how much did your array run you? I don't have gas, so I don't know if I'd break even especially because my house is pretty heavily shaded, but I'd be interested to know about what it cost.
posted by XMLicious at 9:05 AM on November 18, 2011


Total installed cost: $44K
State rebate: -10.5K
Federal tax refund: -12K
State tax refund: -1K
Final out-of-pocket: 20.5K

I also get SREC payments. So far, I've made $1500 from those. That continues for 10 years, then stops.

There's no shade on my roof. Except for a month last winter when snow covered the panels, I've gotten bills from the utility for $0, and they put a credit of $10-15 every month on my account.
posted by Kirth Gerson at 9:35 AM on November 18, 2011 [4 favorites]


Installed cost for my 4.7 kW system was over $5 per. That's inclusive because I didn't want to break out materiel and labor.

Total Installed: $25K
State Rebate: $8K
Federal Credit: $8

Out of pocket: $9K - with some SRECS still due.

Overall, the system is providing 50% of our electricity (as designed) and I figure 10-12 years to pay for itself.
posted by Man with Lantern at 9:43 AM on November 18, 2011 [2 favorites]


Man with -

Those look to me like good numbers but I have one small semantic quibble.

2/3 of the system was paid for by the taxpayers.

10 - 12 years is time to recoup your out of pocket 9K, no?
posted by bukvich at 12:25 PM on November 18, 2011


2/3 of the system was paid for by the taxpayers.
10 - 12 years is time to recoup your out of pocket 9K, no?


Wow, it's just like a REAL power plant! :-)
posted by -harlequin- at 12:54 PM on November 18, 2011 [6 favorites]


Wow. The Congress, in collusion with the oil and nuke industries, actually managed to hold off US companies for so long that the Chinese (!) actually managed to beat us to the magic $1/watt. Marvelous. They will pretty much own all mass-market renewables energy production before long.

On a less dismal note, there are ways that people can group together to empower resilient communities. One is solar farming:

1.The community must own/operate the grid infrastructure that currently supplies them with power. Buy it back if you don't own it already. If this is impossible, you might want to think about moving...
2. Convert the local grid into a smart micro-grid. A micro-grid is a digitized, small scale version of the national grid....

posted by Twang at 3:39 PM on November 18, 2011


They will pretty much own all mass-market renewables energy production before long.

I disagree. A key element of solar panels is that they are modular down to a very low level. This lens itslef well to manufacture and shipping from a site (ie China) if it can achieve a notable cost benefit that offsets transport costs, and given transport is a low level cost the margin for China to capture this advantage is significant. In other Re technologies it is by no means certain that the dominant model will be central manufacture and distribution.

Wind turbine production is very diverse globally (having moved away from being largely EU dominated 15 years ago) and looks likely to continue to be so. Turbines continue to get bigger. Enercon, a major German company, are testing 7MW turbines for offshore use, the bigger the turbine, the bigger the blade, and the more difficulty attached to global dissemination, with the result that companies continue to manufacture on the continent where deployment is likely, effectively where demand is most driven. While this holds (and I think it will for a while to come) then wind will remain diverse.

Wave and tidal are much less technologically and commercially mature and neither are Chinese dominated currently. Again, the tech required will be large scale, so there may be some protection from Chinese market dominance.

In other areas, and particularly renewable heat, China has things sown up. China are massively (and I would say irretrievably) ahead on solar thermal and I would bet they will dominate what is a potentially huge heat pump market.
posted by biffa at 5:02 PM on November 18, 2011 [1 favorite]


When it comes to home based solar and ROI, what is the general opinion of Solar City's residential lease program? I've considered it, but somehow I think I may be missing the "gotcha". Anyone care to enlighten me?
posted by BrodieShadeTree at 7:14 PM on November 18, 2011


In the UK, the government feed in payments to solar installations is encouraging a huge take up of solar on larger installations like farms and industrial buildings. The hedge funds have worked out that they can invest in providing these installations for free to the building owners and earn back their money in 7 years (the installer earns all the feed in bonus after deducting the amount of power the building owner uses each month).

The building owner gets a free solar installation, maintenance and free electrical power for 25 years, the government gets to hit sustainable EU targets and the hedge funds get a nice juicy profit on their investment over the period. Sweet.

In fact the deal was so sweet, the government has just announced a reduction in the feed in tariff to rein in the installation rate. Even so, from what I hear the hedge funds have done a recalc and worked out that the repayment is still viable on a 25 year solar installation (around 9 years or so?). So solar installations are now back on track for the more lucrative installation sizes.
posted by Duug at 5:55 AM on November 19, 2011


(the installer earns all the feed in bonus after deducting the amount of power the building owner uses each month).

Actually the solar panel provider gets the basic tariff for every unit of solar generated, regardless of whether it is used by the landowner or not, they then get an extra 3p/kWh for every unit exported to the grid. (If the land owner buys their own panel they get the same deal.)

In fact the deal was so sweet, the government has just announced a reduction in the feed in tariff to rein in the installation rate. Even so, from what I hear the hedge funds have done a recalc and worked out that the repayment is still viable on a 25 year solar installation (around 9 years or so?). So solar installations are now back on track for the more lucrative installation sizes.

The tariff for installations in the 50kW to 5MW range where cut last August (by about 80% IIRC), which bascially put paid to anything above 50kW. There had been at least 150 projects in the 1MW range being planned in the first half of the year in Cornwall alone but only about 5 got built and the others quit. Oddly the government did this to save money so it could spend on smaller scale projects where the subsidy per unit of energy works out at 50% than for the multi-MW farms. The latest round of government review is to chop the prices for all the other scales, some by over 50%. The problem with all this dicking around is that it not only temporarily halts the market ir underlines market confidence by both those considerng setting up businesses or retraining staff but also by consumers who see the headlines and worry that the price will suddently plummet. As well as the PV tariffs the new UK Government has delayed the introduction of renewable heat policy, it should have started in April this year, first it was split in two, then the first half (commercial and industrial) was delayed until September then again until November, while the second half (domestic) will be delayed until sometime (late) next year.

Essentailly the lessons that the UK and others have spent two decades learning about what makes for effective RE policy (price stability, transparency, etc) has been thrown out and the result will be less new installed capacity and probably more expensive unit cost.
posted by biffa at 3:15 PM on November 19, 2011


Yeah, flywheel batteries seem like the best bet to me with long life, low maintenance, and high power density.

Not to mention entertaining failure modes.
posted by atrazine at 4:24 AM on November 21, 2011


Not to mention entertaining failure modes.

If some accident occurs that discharges all of the power in an energy storage medium at once it's going to be pretty destructive, whether you're talking about the dam bursting in a pumped water energy storage facility, dropping a wrench across the terminals of a lead-acid battery, a tank of gasoline or hydrogen being ignited, or a high-velocity flywheel shattering. I've always found it weird when people who want to put flywheel batteries in cars think that nothing much would happen if the car crashed, that it would just stop spinning or something.
posted by XMLicious at 5:31 AM on November 21, 2011


Some Formula One cars use flywheels. (Not many so far though, because taking advantage of the new regenerative braking rules is happening slowly.)
posted by -harlequin- at 11:33 AM on November 21, 2011


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