photovoltaic economics

ok.

alf

So it costs so much *energy* to make a solar panel. (Some number of Joules.) Will the solar panel make that much energy during it's lifetime? In the past the answer was NO. I have heard that now the panel can actually make more energy than it costs to make. This has nothing to due with the price of electricity... It's just Joules in and Joules out. (If the panel costs more energy than it makes then it's a bust as far as saving energy... it still may be useful in remote or other applications.) All this has nothing to do with whether the panel will save you any money. (The answer to that question is still NO.)

George H.

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It hasn't been the case for quite a while although the net energy gain is puny at high latitudes. Energy yield ratio of 4 in UK or 7 in a decently sunny country like Australia.

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Depends whether or not you include the daft subsidies that various governments have given to alternative energy. The ROI for UK PV installations last year (including the daft FIT) was over 8%! (and tax free - quite a market distortion and even worse in Germany)

This is utter madness as an energy policy but it stems from our civil servants and ministers being mostly classicists and lawyers who dropped maths and science at the earliest opportunity.

's ok.

n half

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dies

OK so the 4 year time frame for energy pay back quoted in the OP's link is at least a reasonable number.

Wow, I didn't know it was that 'good' in the UK. I heard that in Germany you were paid something like $0.50 per kW-hr for PV electricity you put into the grid.

Yeah, And shutting down all those dangerous nuclear plants after so many people died at Fukushima, :^)

Oh wait, no deaths. So why are nuclear plants being closed?

I was hoping for some sane energy ideas when Steven Chu was energy secretary here. (he didn't make much of a splash.)

George H.

This might help: It shows a payback in about 2.5 years which looks like the most optimistic possible estimate. Some details:

- 18% module efficiency is a bit high as it doesn't consider the drop in output over time.

- 80% overall efficiency is also a bit high, as it assumes that the system is operating at maximum rated power level. At lower power levels, inverters are not as efficient.

- It ignores the approximately 1% decrease in output for every 1C increase in temperature.

- Solar radiation varies radically by location. For the US left coast, about 1500 kWh/m2/year. Most of Europe is about half that.

Throwing in these considerations, my guess(tm) is about 8 years EPBT.

Well we are at least taking some small effort to follow China's lead in nuclear power plant construction. Not sure which energy secretary (if any) was involved in the loan guarantees that made our 4 new reactor projects possible, but from:

"There's no question it's a big deal," says Neil Wilmshurst of the Electric Power Research Institute in Palo Alto, California. "There were no new plants being constructed for decades, and now there is a new wave of building going on."

What seems like a sudden rush back to nuclear was actually put in motion years ago, when US utility companies began to pre-empt the possibility of government-mandated cuts in carbon emissions. But to get construction under way, the firms needed a big helping hand from the government. As part of President Barack Obama's goal of promoting clean sources of energy, he guaranteed $8.3 billion in federal loans for the reactors, which helps spread the massive cost of the projects.

All four new plants will be AP1000s. These reactors are descendants of the ones that have been in service since the middle of the 20th century. However, they have major safety upgrades, new pump designs and more straightforward circulation systems. More exotic designs remain on the horizon, such as reactors powered by thorium fuel, but the AP1000 and other more conventional designs are important for one simple reason: they are being built. That means adding reliable, low-carbon energy to the US grid on a scale that other technologies can't yet match.

Whether the construction signals the start of a US nuclear energy boom remains to be seen. Reactors are expensive and fossil fuels are cheap enough that utility companies are nervous about undertaking such long, costly projects. "It's a bet-the-company proposition," says Wilmshurst.

That's not the case in China, where massive government backing has allowed construction there to race ahead of the US. Across China, 28 reactors are being built, many of them AP1000s, including one nearing completion at the Sanmen Nuclear Power Station in Zhejiang Province. It will become the first operative AP1000 if it comes online later this year as planned.

It's not an energy policy. It's a relatively inexpensive way of conducting research into photovoltaic feasibility under real conditions at thousands of sites across the country. Much, much cheaper than a government research agency, and much more representative.

It's actually quite a clever idea.

Cheers

If the subsidy is high enough it will save some people money at the expense of other people. But it has no large scale benefit unless a significant fraction of the population does it, and then they're paying for the subsidy themselves.

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Our house (in Northern California) came with 2 kW solar panels, and earns a bout $1/day on average. The homebuilder told us the panels and inverter co st $11,475. (We didn't pay any extra for the solar stuff... it was a decis ion they made before they found buyers for the house)

So, figure $365/year... 10 years that's $3,650... oh, wait, assume the elec tric bill goes up 3% each year too, so... enjoy the calcs.

No. It is dumber than a rock. No-one in their right mind would install expensive photovoltaic systems at latitudes >40 degrees. UK is 50-60 N and fairly often covered in cloud. PV here is a waste of time in winter.

It makes sense for sub tropical latitudes with plenty of sunshine but it is insane to subsidise rich people in the UK to get 8% tax free on renewables at the expense of the average poor consumer of electricity.

We have a big scandal of aggressive payday loan companies targeting the penniless unfortunates with typical APRs of 2000+% and the generous offer of continued use of their kneecaps if they keep up the payments.

The OFT is looking into it, but like all our government "watchdogs" are toothless, supine, myopic and incompetent in about equal measure. BTW that is the opinion of the government committee that oversees them...

The people who make policy have always funded research agencies when they wanted research, so research was not their intention at all with these subsidies. Their intention was to make people do what they want.

Bollocks. Research is the only way to find out. You say, "PV here is a waste of time in winter" but that it, "makes sense for sub tropical latitudes", which may well turn out to be be true, but that's just assertion; we need measurements. Of course it's better where there's more sun, but who are you to draw the go/no go latitude line without real information?

And what the f*ck do payday loan companies have to do with anything?

Again. It is not an energy policy, it is a big experiment.

It is quite probably true that PV here is currently a loser. It is almost certainly true that it will become cheaper and more efficient. It is possibly true that it will one day be a winner. I don't know, and nor do you. It makes sense to run the experiments.

Cheers

The thickness of the wafers is a big deal. For your garden variety chip, they make the wafer thick enough not to "lose" wafers in processing, i.e. breakage. Where that thickness comes is some black magic. For mounting in a package, the water is back-lapped to make it thinner. [Not to be confused with the initial lapping just to remove surface cracks caused by the diamond saw.] But a solar cell isn't all that complicated, so they might be thinner than your typical silicon wafer. Given the energy to make the ingot is a fixed amount, the thinner the wafer, the less energy required to produce it. i.e. you get more wafers per the given ingot.

The much maligned Solyndra was NOT making silicon solar cells. They were making thin film solar collectors, a very energy efficient process. Unfortunately the bad press from the reactionary wing nuts has tainted thin film solar collectors. The problem was they couldn't compete with the Chinese Chinese crap.

The sunshine statistics are well known for the UK and have been since the 1970's OPEC induced energy crisis when the first proper research into the viability of solar was done. The result was that hot water was just about worthwhile provided you wanted it all in mid-summer.

PV was a non-starter then and remains so now - you need something like a return on energy invested in making it of 10:1 to be worthwhile. At present even in the best ideal conditions 7:1 is the practical limit.

It might improve but until it does any that are made should be installed in places where they will do the most good!

In this case transfer money for overpriced electricity from the pockets of the poorest people in society to the richest who could afford the investment in these highly subsidised boondoggles. I have even seen them installed under trees - it makes no difference you still get paid.

The same is also true of wind turbines - a fair proportion of them here are installed to farm the grants rather than the wind since the operators are paid for installed *capacity* irrespective of their yield!

They often have to drop the more remote ones off grid and feather them because the rural distribution network cannot take the peak power when it is very windy. That is a hazard of an intermittent supply.

Like nearly all manufactured products the embodied energy cost is just a small fraction of retail cost ..

PV Energy payback time is small fraction of net ROI payback..

In sunny climates I put it at .3 to 6 months..

small fraction of

Maybe if you add a few Zeros behind those figures. I expect the energy expended to ship them to where they are installed would add a year to the figures. And then you have the energy to produce the material for the frames.

Dan

fraction of

You are completely wrong. Making refined silicon is expensive.

PV energy payback is about 3-4 years for PV arrays assuming the most favourable geometry *and* a very sunny location. In the UK it is more like 6-10 years depending on exactly how poor the summers are.

Wind turbines in the right location will payback considerably faster.

You do realize there are economic costs associated with fossil fuel or nuclear energy that are born by other consumers. For instance, the increase in green house gases created by fossil fuel and nuclear power are a social cost. [Yes, nuclear power creates greenhouse gases.] The nuclear industry receives huge subsidies via DOE "research".

Ronald Reagan was wrong. There is no free lunch.

We all do, but you don't realize that people can evaluate economic costs and make the best choices without dictates.

The government isn't doing that research as a favor. It has approval over nuclear designs, not solar designs.

How are they supposed to determine what designs are ok if they don't do their own research?