Energy to create Solar Cells?
Question:
It takes more energy to manufacture a solar cell than the cell will produce in it's lifetime.
Can't seem to find anything definitive on the web.
Answer:
It depends a little on what sort of cell and where it is used. The main problem is that the silicon needs to be EXCEEDINGLY pure - and with the exception of the polycrystalline cells, the cells have a very finite life.
Most of the amorphous ones are producing less than half rated power in about 5-7 years and next to useless in about 10-12.
If you plonked any *modern* polycrystalline cell in a country which enjoys HUGE amounts of bright sunshine all year around, then it WILL sooner or later produce more power than it took to make it.
Any other cell (current technology) and certainly in less favourable sunlight conditions will have failed before it reached unity.
One particularly ghastly scan was done in Sri Lanka about four years ago, a very impressive sales pitch was made on the wonders of solar electricity (electricity not available in many parts of SL), the locals were given credit agreements to sign and their panels installed. Even when they were first put in, the output was a fraction of what was promised - spec given for the best polycrystalline panels, delivered was a poor type of amorphous panel. Now 4 years down the line, most panels have reduced their output (such as it was) by over half. Alas there do not have "trading standards" in SL, just money collectors with guns and wooden clubs to encourage you to pay on time. A digression I agree - but I wanted to illustrate the difference between old and new design panels.
The biggest problem is the energy input required to make the silicon pure, the rest of it is *reasonably* ok. We shall ignore the energy requirements to make the glass they are bonded too and the substantial amount of power to produce the aluminium backing.
Solar cells DO have a place (remote power etc etc) but from an environmental point of view, they really have some way to go before they truly benefit the planet.
A far more useful way of extracting power from solar is to use panels to heat hot water, not only for central heating / hot water - BUT if used with reflectors and focused on a single point, VERY high temperature can be attained sufficient to drive steam turbine engines - there are a few commercial plants that do this today. http://americanhistory.si.edu/powering/i... being one case in point.
Hopefully in time, cells will become more efficient, more economical ways of making pure silicon will be found and the use of solar for making electricity directly WILL become more practical from a "green" point of view.
Well, I think Solar cells are still expensive!
well, I think Solar Cells receive energy from "light energy" - photons.
.?
And it takes O2 to live, I'll take the solar cell !
I believe that the energy cost of producing solar cells has gone down significantly in the last few years. That is, it now takes less energy to produce them than it did in years past. It would be interesting to contact whomever made that statement, and ask them for their data. Solar cells last a long time, and now produce more energy per square foot than ever before, so over it's lifetime, a solar cell produces a heck of a lot of energy. Food for thought though. Good question!
This statement is made in the book "Gaviotas" and the way they explain it, it is true for photovoltaic cells, but water heating solar panels take much less energy to produce, and have a long life expecancy, so they are better.
ya , thats y they r more expensive
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