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Published on March 15th, 2013 | by Giles Parkinson


Energy Payback Of Solar Rocks It! (Graph)

March 15th, 2013 by  

Reposted from RenewEconomy:

Today’s Graph of the Day is a simple one, and is designed to dispel the myth about energy pay-back times, at least for solar PV. Some anti-renewable commentators and myth-makers would have us believe that solar PV modules do not pay back the energy used to create it. It’s not true.

This graph of the day was presented by Muriel Watt, the chair of the APVA, at a seminar on Community Power in Sydney that I chaired on Wednesday. It’s not a new graph, but demonstrates that the payback is actually very quick.

The energy payback time in which the energy input during the module life‐cycle is compensated by electricity generated by the PV module depends on several factors, including cell technology, PV system application, irradiation, the sources of energy used in its manufacturing processes and the energy the PV will displace.

For a typical 2 kWp rooftop system, the energy payback time is 2 to 3 years using multi‐crystalline modules and more than 7.5 times the energy used in its manufacture is generated over a 20 year life. For thin film modules, the payback time is half that of crystalline modules, but the lifetime may be shorter.

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About the Author

is the founding editor of RenewEconomy.com.au, an Australian-based website that provides news and analysis on cleantech, carbon, and climate issues. Giles is based in Sydney and is watching the (slow, but quickening) transformation of Australia's energy grid with great interest.

  • Ivor O’Connor

    The graph does not look right. I tried putting a ruler up to it and it certainly looks off scale.

  • Billy Dee Sorrells

    Two things I figure someone should point out. Your graph is incorrect because solar panels energy is degraded every year of use by the end of their life cycle they can be as low as 35% of the original output, therefore a flat bar is not accurate. Two you did not mention the hazardous sludge that is created by making solar panels. Even with those it is still a better alternative than petrol, but you make yourself seem untruthful by not disclosing all the facts.

    • Bob_Wallace

      Well, since solar panels lose about 0.5% output per year the end of life cycle you’re talking about would be 70 years, not the 20-30 years in the article.

      And the “hazardous sludge” – where does one find that? Is it anything like mountains of fly ash or uranium tailings?

      • Billy Dee Sorrells

        http://www.washingtonpost.com/wp-dyn/content/article/2008/03/08/AR2008030802595.html that’s sludge. As for the degradation rate I guess you’re right the my information was old data the current agrees with you

        • Bob_Wallace

          Yes, there is industrial waste created by solar panel manufacturing. And some Chinese plants were dumping it inappropriately back in 2008 when your article was written.

          China has cleaned up some since. How much, we don’t know.

          The US disposes of their waste appropriately. It’s trucked to dumps which are designed to contain the waste. China needs to be doing the same, if they aren’t.

          Now, let’s go back to my question. ” Is it anything like mountains of fly ash or uranium tailings?” Here’s what Wiki has to say about coal fly ash –

          “In the United States about 131 million tons of fly ash are produced annually by 460 coal-fired power plants.”

          In 2012 China burned 4.3x as much coal as the US, so 563 million tons of fly ash for China might be a good estimate.

          And from your link –

          ” The combined capacity of these new factories is estimated at 80,000 to 100,000 tons”

          100k tons is 1.7% of million tons.

          Molehill, meet mountain….

    • Ivor O’Connor

      I’ve heard right wing talk show hosts talk about all this horrible toxic sludge that is produced when making PV panels. Perhaps that is what you are referring to?

  • globi

    Meanwhile a PV-system and an economy car together are cheaper than a pick-up truck.
    The two best selling cars in the US are pick-up trucks, but for some reason nobody talks about their energy payback respectively their massive energy loss…

    • “two best selling cars in the US are pick-up trucks” — are you serious? that’s shocking to me. can you provide a link/source?

    • Bob_Wallace

      I don’t think pickups are going to hold the tops spots for much longer, if they still do. It seems to me that we’ve passed the pickup fad phase like we earlier passed the SUV and the earlier minivan fad phases.

      Most “pickups” now being sold are not really pickups. They’re four door sedans with trunks without lids. Those mini-beds are an insult to pickups. Can’t haul a decent load of horse poop for the garden in one of those things.

  • anderlan

    It makes total sense that the energy “profitability” point would be same time as the monetary profitability point because the cost of manufacturing energy is a good component of the whole cost of something made largely of sand and a handful of aluminum cans.

    There is a rash of conservative articles talking about the carbon intensity of EV batteries and solar panels. Have these outlets suddenly gotten carbon-footprint religion? No, of course not. They are simply showing that they are subservient to the old order, and to the companies that take the depend on constantly taking a share of the money of hardworking people forever and ever–petrol, gas, and power companies.

    Suddenly, when the money argument for EVs and solar panels starts to make sense for a good portion of the people, suddenly these conservative outlets are not concerned about saving you and me money on gas or power, but on the environment. WHAT?!?

    No. As I said the energy (carbon intensity) cost of panels and batteries are rolled into the price by the market. (AND, the energy can come from any number of sources, not just carbonaceous ones.) SO, when the economics make sense, so do the climate concerns. It’s hilarious that these pundits would, after having been so concerned about the economic equation not working for the people of the world for sooo long, that they now are concerned about the greenhouse gas impacts the moment the economic equation looks good. Don’t let the greedy lying bastards keep taking our money.

    • excellent comment, thanks!

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  • When solar gets cheapest form of energy, then we can produce solar electricity to manufacture solar panels. Then the payback time drops into zero.

    There is also good to consider that both silicon and aluminum frames are fully recyclable. This halves the actual energy payback time.

    • Bob_Wallace

      I suspect we are already putting more electricity on the grid in a year than we are using to manufacture panels during that year.

      One could probably guestimate it by taking the total number of installed watts, multiplying by about 0.2 (capacity) and then by 0.5 (energy recovery time) and see if that number is higher than the wattage of panels we’re producing.

      • Benny

        No I will never give my solar energy to the grid, I’d rather waste the excess I produce then give it to cowboys that don’t care about the planet. These cowboys are those who live on the grid pretending to save the planet, while living on coal energy, unlike me who is self-sufficient and self sustainable, supplying all my own energy needs without been connected to the grid, unlike these cowboys with grid connected solar system cashing in for a buck. While people like me did the right thing by the environment, while those other people with grid connected solar systems are damaging the environment and been dependent on subsidies…

        • the biophysicist

          being off grid when there is already a grid there makes about as much sense as driving off road when there is already road there

    • Good point. 🙂

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