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Author here. Good you mention this. I could have chosen a more elegant citation, but data on the embodied energy of PV modules is generally outdated and confusi

Author here. Good you mention this. I could have chosen a more elegant citation, but data on the embodied energy of PV modules is generally outdated and confusing. The number I chose is not especially high for panels produced since the 2000s. For an extensive literature summary from 2011 see 2.3 http://www.seas.columbia.edu/clca/Task12_LCI_LCA_10_21_Final_Report.pdf http://www.seas.columbia.edu/clca/Task12_LCI_LCA_10_21_Final... Also keep in mind that all the panels we tested are much smaller than the ones oin those studies. This means that things like the frame, wires, connections become more important for embodied energy.

philipkglass 7y ago
That study is also badly outdated. Under section 5, Life Cycle Inventory Data, it says "The authors have assembled this LCI data set to the best of their knowledge and in their opinion it gives a reliable representation of the crystalline silicon module production technology in Western-Europe in the year 2005/2006 and Balance-of-System components of the year 2006." I would love to see a life cycle assessment using wholly up-to-date numbers. I keep reading new studies on PV LCA, energy return on investment, and/or energy payback time. People who write these sorts of papers don't seem to keep up with what industry is actually doing. You can learn a lot from data sheets and trade publications. E.g. from published glass thickness and module size and efficiency, you can calculate the quantity of glass currently needed per watt-peak. It's significantly lower than any of these studies using decade+ outdated numbers. I think part of the problem is one of incentives. Academics writing about LCA are often comparing some hoped-to-be-up-and-coming technology against the mainstream. Like thin film PV, organic PV, or dye sensitized cells pitted against crystalline silicon PV. In that case using old numbers for silicon PV helps the newer technology look like it offers exciting improvements. Another problem is that reviewers apparently don't care very much about these temporal effects. They don't chase the citation chains to find the really outdated measurements cited in recently submitted manuscripts. Another problem is that the solar industry has grown large and competitive. Cutting-edge numbers about energy consumption for silicon refinement are probably retained as a competitive advantage by the biggest producers, for example. It's possible to set tighter upper bounds on resource intensity just from teardowns of recently manufactured modules. I suppose that teardown based analysis may itself be the sort of information you only get from specialty publications like the Photovoltaics International magazine, which is expensive and not indexed by DOI or part of ordinary academic libraries. (So it's not even in sci-hub.) It's $599 a year if you want to be able to read back issues of Photovoltaics International from their archives: https://store.pv-tech.org/photovoltaics-international/ https://store.pv-tech.org/photovoltaics-international/ I am interested enough in photovoltaic technology that I have bought a couple of $100+ specialty books from academic publishers, but $599 is a bit too steep even for me.
- lowtechmagazine 7y ago
  The obsolescence of life cycle analyses is a topic in itself, and the lack of accessible data is a problem for anyone who tries to investigate high-tech products. For the solar powered website article, it's the order of magnitude that matters. You say I overestimate the energy use of solar panel production, but in our configuration it corresponds to just 1 liter of oil per year.
  - kragen 7y ago
    You can get a reasonable estimate by taking the wholesale price of the thing you're analyzing, dividing by an average price of electricity for industrial use (like, around US$60/MWh, in the quaint non-SI units traditionally used in the trade), and multiplying that by some fudge factor like 20% to account for the fact that much of the cost of things is due to non-energy inputs like raw materials, skilled labor, and interest. This gives a result correct to within a factor of 3 for the vast majority of goods and services, while using LCA numbers from a quarter century ago did not. In this case the result is 2.3 MJ per watt (peak) of low-cost solar panels using €0.17/Wp from PVXchange and SolarServer. That's almost an order of magnitude lower than the 22 MJ/W you used in the article (assuming 16% efficiency; with 21% efficiency it's 16.7 MJ/W. I'm not sure which one your original number was for.) So I think you may have gotten within an order of magnitude, but only just. If the numbers you were using were correct, then just the energy input for the solar panels would have cost more than the wholesale price for the modules.
    - lowtechmagazine 7y ago
      Calculating embodied energy based on costs is an option, but I have always learned that it's the last resort, as it has many problems, too. For example, How do you account for the fact that all production facilities for solar panels have moved to China? If you look at the price evolution of solar panels, there's a gradual decrease due to technological progress (less energy use indeed). Then, from 2009 onwards, the decline in costs accelerates sharply, the consequence of moving almost the entire PV manufacturing industry from western countries to Asian countries, where labor and energy are cheaper and where environmental restrictions are more loose. https://solar.lowtechmagazine.com/2015/04/how-sustainable-is-pv-solar-power.html https://solar.lowtechmagazine.com/2015/04/how-sustainable-is...
deleted 7y ago
[deleted]

philipkglass 7y ago

That study is also badly outdated. Under section 5, Life Cycle Inventory Data, it says "The authors have assembled this LCI data set to the best of their knowledge and in their opinion it gives a reliable representation of the crystalline silicon module production technology in Western-Europe in the year 2005/2006 and Balance-of-System components of the year 2006." I would love to see a life cycle assessment using wholly up-to-date numbers. I keep reading new studies on PV LCA, energy return on investment, and/or energy payback time. People who write these sorts of papers don't seem to keep up with what industry is actually doing. You can learn a lot from data sheets and trade publications. E.g. from published glass thickness and module size and efficiency, you can calculate the quantity of glass currently needed per watt-peak. It's significantly lower than any of these studies using decade+ outdated numbers. I think part of the problem is one of incentives. Academics writing about LCA are often comparing some hoped-to-be-up-and-coming technology against the mainstream. Like thin film PV, organic PV, or dye sensitized cells pitted against crystalline silicon PV. In that case using old numbers for silicon PV helps the newer technology look like it offers exciting improvements. Another problem is that reviewers apparently don't care very much about these temporal effects. They don't chase the citation chains to find the really outdated measurements cited in recently submitted manuscripts. Another problem is that the solar industry has grown large and competitive. Cutting-edge numbers about energy consumption for silicon refinement are probably retained as a competitive advantage by the biggest producers, for example. It's possible to set tighter upper bounds on resource intensity just from teardowns of recently manufactured modules. I suppose that teardown based analysis may itself be the sort of information you only get from specialty publications like the Photovoltaics International magazine, which is expensive and not indexed by DOI or part of ordinary academic libraries. (So it's not even in sci-hub.) It's $599 a year if you want to be able to read back issues of Photovoltaics International from their archives: https://store.pv-tech.org/photovoltaics-international/ https://store.pv-tech.org/photovoltaics-international/ I am interested enough in photovoltaic technology that I have bought a couple of $100+ specialty books from academic publishers, but $599 is a bit too steep even for me.

lowtechmagazine 7y ago
The obsolescence of life cycle analyses is a topic in itself, and the lack of accessible data is a problem for anyone who tries to investigate high-tech products. For the solar powered website article, it's the order of magnitude that matters. You say I overestimate the energy use of solar panel production, but in our configuration it corresponds to just 1 liter of oil per year.
- kragen 7y ago
  You can get a reasonable estimate by taking the wholesale price of the thing you're analyzing, dividing by an average price of electricity for industrial use (like, around US$60/MWh, in the quaint non-SI units traditionally used in the trade), and multiplying that by some fudge factor like 20% to account for the fact that much of the cost of things is due to non-energy inputs like raw materials, skilled labor, and interest. This gives a result correct to within a factor of 3 for the vast majority of goods and services, while using LCA numbers from a quarter century ago did not. In this case the result is 2.3 MJ per watt (peak) of low-cost solar panels using €0.17/Wp from PVXchange and SolarServer. That's almost an order of magnitude lower than the 22 MJ/W you used in the article (assuming 16% efficiency; with 21% efficiency it's 16.7 MJ/W. I'm not sure which one your original number was for.) So I think you may have gotten within an order of magnitude, but only just. If the numbers you were using were correct, then just the energy input for the solar panels would have cost more than the wholesale price for the modules.
  - lowtechmagazine 7y ago
    Calculating embodied energy based on costs is an option, but I have always learned that it's the last resort, as it has many problems, too. For example, How do you account for the fact that all production facilities for solar panels have moved to China? If you look at the price evolution of solar panels, there's a gradual decrease due to technological progress (less energy use indeed). Then, from 2009 onwards, the decline in costs accelerates sharply, the consequence of moving almost the entire PV manufacturing industry from western countries to Asian countries, where labor and energy are cheaper and where environmental restrictions are more loose. https://solar.lowtechmagazine.com/2015/04/how-sustainable-is-pv-solar-power.html https://solar.lowtechmagazine.com/2015/04/how-sustainable-is...

deleted 7y ago

[deleted]