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Sunday, March 09, 2008

A word on solar panels

If you're thinking of solar panels as a way to reduce CO2 emissions, you may need to think again. Especially if you live in a northern climate like, say, Canada.

courtesy of Tom Nelson

The ugly side of solar panels.

Solar panels don’t come falling out of the sky – they have to be manufactured. Similar to computer chips, this is a dirty and energy-intensive process. First, raw materials have to be mined: quartz sand for silicon cells, metal ore for thin film cells. Next, these materials have to be treated, following different steps (in the case of silicon cells these are purification, crystallization and wafering). Finally, these upgraded materials have to be manufactured into solar cells, and assembled into modules. All these processes produce air pollution and heavy metal emissions, and they consume energy - which brings about more air pollution, heavy metal emissions and also greenhouse gases.

For myself, my concern with solar panels has been more with how they're made and what they're made of. My big surprise in reading this was the efficiency of solar panels. I hadn't realized it was so poor.

The researchers investigated 4 types of solar cells: multi-crystalline silicon (with an efficiency of 13%), mono-crystalline silicon (14%), ribbon silicon (11.5%), and thin-film cadmium telluride (9%).
Only 9-14% efficiency??? Yikes!

In the best case scenario, one square meter of solar cells carries a burden of 7,527 kilograms of CO2. In the worst case scenario, that becomes 31,416 kilograms of CO2. An average household needs at least 8 square meters of solar panels for electricity generation alone (make that 10 in the US), which boils down to a global warming debt of a whopping 60,000 to 940,000 kilograms of CO2. These numbers equate to 12 to 188 intercontinental flights.

If you've gone to the link and read the article, you'll note that the report is based on a 30 year life expectancy in a Mediterranean climate. It's a different story if you live elsewhere, and the life expectancy is a supposition - there are many reasons for life expectancy to differ, ranging from inability to withstand a harsher climate, to accidents, to simply wanting to upgrade to better panels as technology improves.

In conclusion...

All this does not mean that PV solar energy should not be promoted. ... But some facts have to be faced. First, solar cells are far from a zero emission technology. Two: solar panels can be a doubtful choice in less sunny regions. Three: solar panels mounted on gadgets are completely insane. Four: solar cells should be recycled. Five: some law or incentive should be introduced to guarantee a life expectancy of 30 years. And if possible, solar thermal power should have priority over solar PV power.

It should be realized that solar panels first raise the amount of greenhouse gases before they help lowering them. If the world would embark on a giant deployment of solar energy, the first result would be massive amounts of extra greenhouse gases, due to the production of the cells.


I did not do the calculations for air pollution and heavy metals, but since these are mainly produced by energy use for production, the conclusions must be similar.

© Kris De Decker (edited by Vincent Grosjean)

See the whole thing here.

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