What have you done today to lower your impact?

We are washing away the foundations of our existence on every front. It is high time we move from crashing about on the planet like a bull in china shop and find a way to go forward with intent. We must find systems of living based on sustainability. The systems and tools exist, it is up to each of us to adopt them.

Blog Archive

Tuesday, 19 May 2009

Energy Payback on Solar Panels

Let's put this one to rest shall we? People keep asking me if solar panels don't actually take more energy to manufacture than they will ever produce. NO, NO, NO!

A new life cycle assessment adds yet another scientifically sound voice to that point. Read more in this article by Jeremy Faludi over at WorldChanging. Here is an excerpt;

" A recent life-cycle analysis published at the Institute of Science in Society (ISIS) showed that in a nice sunny place like Spain, PV panels reach energy payback (when they've saved as much fossil fuel as it took to make them) in about one to three years, depending on the type of panel. Interestingly, the new thin-film chemistry cadmium telluride (CdTe) fared best at 1.1 year despite having the lowest efficiency (9%), while monocrystalline silicon fared worst at 2.7 years despite having the highest efficiency (14%). This may seem counterintuitive, but the explanation is simple: it takes a lot less energy to make CdTe film....If your climate is less sunny than Spain, there will obviously be a longer payback time; but most of the continental US gets as much solar radiation as the location in the study. (It got 1,700 kWh/m^2/year, which is 4.7 kWh/m^2/day...."

I must say however that PV observers have been predicting the dominance of thin film over cyrstalline panels for close to 20 years and it never seems to happen. I hope Mr. Faludi is right but this next bit is worth taking with a grain of salt.

"Though thin-film PV panels have been in the market for more than a decade, the new chemistries that are coming to maturity (mostly CdTe and copper indium gallium selenide, "CIGS") are fundamentally changing the game. They are still not as efficient, but they are good enough, and they are far cheaper (up to 1/3 the cost per watt), even before reaching true economies of scale from mass-manufacturing. Now we see that they are environmentally preferable as well, since they have faster energy payback times. In the years ahead, crystalline silicon will become relegated to satellites, mobile systems, and other applications where compactness is king, while thin-film PV will be the default style. Crystalline prices will stay high, but thin-film prices will continue to drop steadily until they hit grid parity (arguably they have already), at which point they will plummet because manufacturing will ramp up massively. CdTe and CIGS will ultimately be price-limited by the rarity of their ingredients; the next wave after them will be dye-sensitized solar cells, made from common titanium dioxide and organic dyes. It'll be probably ten years or more before those dominate, though, and in that much time, who knows what other chemistries will come along? In any case, keep an eye out for it: the future of PV is thin."

No comments: