4 ms·

Do solar panels produce more energy that the amount required to create and operate them? (including mining the materials)

armenarmen 10y ago
No one ever really likes to provide these numbers. Hopefully they are a net gain, but I'm a bit skeptical
proee 10y ago
In doing a quick google search on this question, it seems to be "YES". Payback is in the 4 year range where the service life of the panel is in the 20-plus year range.
philipkglass 10y ago
Yes: http://www.mdpi.com/1996-1073/9/8/622/htm http://www.mdpi.com/1996-1073/9/8/622/htm Energy pay-back time (EPBT) results for fixed-tilt ground mounted installations range from 0.5 years for CdTe PV at high-irradiation (2300 kWh/(m^2·yr)) to 2.8 years for sc-Si PV at low-irradiation (1000 kWh/(m^2·yr)), with corresponding quality-adjusted energy return on investment (EROIPE-eq) values ranging from over 60 to ~10. If you want to see other publications on the same topic, try hitting Google Scholar with search terms "photovoltaic" "life cycle" "energy payback". For the most accurate results, restrict your search to recent years. Manufacturing processes are revised rapidly and studies from the turn of the millennium are now badly obsolete. (Though even in 1990 PV systems were net energy positive on average; the worry that PV system manufacturing consumes more energy than the lifetime output appears to be a holdover from the very early (1970s) days of terrestrial PV systems.)
- ars 10y ago
  I'm skeptical of your numbers. With such a quick payback time you'd expect to see solar power going up like crazy. (Like how wind was being installed quite fast for a while - although only in the best spots.) Except you don't, you just see limited installations here and there. If solar power has such a quick payback period why aren't more investment groups funding it? Are the panels not available in sufficient quantity?
  - brokencode 10y ago
    The main problem with solar is that it is not a full replacement for current power plants, since it does not produce power at all times. Until we have the capacity to store energy to use at night and on cloudy days, solar will be limited in potential. I think his numbers didn't take into consideration the expensive backup power plant that you have to have ready even if you have adequate solar capacity.
  - philipkglass 10y ago
    Solar power is going up like crazy. The US just had its highest-ever quarterly solar installation rate, up 191% over Q3 2015: https://www.greentechmedia.com/articles/read/in-its-largest-quarter-ever-us-solar-market-saw-nearly-2-mw-of-pv-installed https://www.greentechmedia.com/articles/read/in-its-largest-... Global installations for 2016 are also on track to set a new record, surpassing 2015 installations by 48%: https://cleantechnica.com/2016/11/30/global-solar-installations-reach-76-gw-2016-mercom/ https://cleantechnica.com/2016/11/30/global-solar-installati... And despite these records, the manufacturing side of the industry is currently demand-constrained rather than supply-constrained. When you say you there's just "limited installations here and there," are you estimating from whatever you personally see in your local area?
  - beefield 10y ago
    Energy payback time is a different concept than money payback time. Investors are interested in the latter, First one is a rudimentary requirement for long term feasibility without subsidies. Also, global solar is going up like crazy. Global sustained growth rate of around 40% is crazy fast. If that keeps on for a bit more than ten years, 100% of current global electricity demand is covered by solar. Just for comparison, there exists no two subsequent full years of iPhone production where Apple would have managed to achieve 100% growth.
  - mikekchar 10y ago
    I have to echo the statement that PV is going up like crazy -- at least where I live. Admittedly I'm in one of the sunniest places in Japan (and at 34 degrees latitude to boot). They are clear cutting forest to put up installations everywhere. Virtually every single apartment building already has solar panels on top of them. Every house builder offers solar panels on new houses and while I've seen a couple of new houses without them, they are definitely the exception. Every electronics store sells solar panels and usually it is the thing that they are pushing hardest (weird to see huge solar panel displays next to the refigerators and TVs). I've done the math and with the price of electricity we pay here, it is a complete no brainer to get solar panels. If I lived in a house, I wouldn't even think twice.
epistasis 10y ago
The term is EROI (energy returned on energy invested), for renewables its currently roughly equivalent to fossil fuels and getting higher as the technology improves. As oil and natural gas get more expensive and energy intensive to extract, their EROI is going down.
- chillydawg 10y ago
  Going down from a fantastically high return to a slightly less fantastically high return.
  - epistasis 10y ago
    Yes, but it's going to continue to go down. According to Wikipedia [1] EROI Fuel ---- ---- 35.0 Oil imports 1990 18.0 Oil imports 2005 12.0 Oil imports 2007 6.8 Photovoltaic (wikipedia) 14.4 Photovoltaic [2] (from recent analysis of post-2008 data) The trend lines are clear and stark. The technologies for photovoltaic, wind turbines, and for fossil fuel extraction are all changing. It's certainly not the case that fossil fuels will disappear, but over the coming decades the sector will shrink dramatically due to market forces; investments will plummet. And once you start looking at the slow and steady pace of improvement in storage technologies, it looks highly possible that around 2025-2030, only specialized energy applications ever make new investments in fossil fuel based technologies. And that's without accounting for the negative externalities that fossil fuel users (all of us) make everybody else subsidize. Existing infrastructure will continue as long as its economical, of course, but there's most definitely a huge turning point around the corner in energy technology. [1] https://en.wikipedia.org/wiki/Energy_returned_on_energy_invested https://en.wikipedia.org/wiki/Energy_returned_on_energy_inve... [2] https://www.researchgate.net/publication/311170056_Solar-PV_energy_payback_and_net_energy_Meta-assessment_of_study_quality_reproducibility_and_results_harmonization https://www.researchgate.net/publication/311170056_Solar-PV_...
    - ZeroGravitas 10y ago
      I believe those EROI numbers also don't include converting the energy into the useful output that you need and so are a a pointless apple-to-oranges comparison PV output is electricity already, to get electricity from coal you'd need to throw away 2/3rds of the energy as heat, about half for gas, reducing their EROI by that factor in a correct comparison. So if it's electricity you want then PV is already winning over fossil fuels I think. Similarly, for powering cars with gasoline they're not as efficient in converting that energy "well-to-wheel" as EVs, as the losses in battery storage and electric motors are much smaller, giving you a "miles driven return on energy input" measure about 3x higher for a PV charged car vs ICE. You can avoid the generation loss on natural gas by piping to the home and burning it directly for heat in areas that need heat, getting close to 100% efficiency with modern central heating systems, but then in those same situations you can use an electric heat pump and get 3-500% efficiency, since you're only moving the heat around, not generating it.
intrasight 10y ago
Was also discussed (more in terms of carbon footprint) in The Economist this week: http://www.economist.com/news/science-and-technology/21711301-new-paper-may-have-answer-how-clean-solar-power http://www.economist.com/news/science-and-technology/2171130...
jaclaz 10y ago
Don't forget the costs to dispose of them once they are not producing energy (or enough energy), typically after 15 to 20 years, and the overcosts for replacements due to "natural" events, like hailstorms.
- smaddox 10y ago
  There could actually be an interesting secondary market for solar cell recycling. My understanding is that the primary degredation is due to the contacts, which could likely be reapplied or annealed in order to reach their original efficiency.

armenarmen 10y ago

No one ever really likes to provide these numbers. Hopefully they are a net gain, but I'm a bit skeptical

proee 10y ago

In doing a quick google search on this question, it seems to be "YES". Payback is in the 4 year range where the service life of the panel is in the 20-plus year range.

philipkglass 10y ago

Yes: http://www.mdpi.com/1996-1073/9/8/622/htm http://www.mdpi.com/1996-1073/9/8/622/htm Energy pay-back time (EPBT) results for fixed-tilt ground mounted installations range from 0.5 years for CdTe PV at high-irradiation (2300 kWh/(m^2·yr)) to 2.8 years for sc-Si PV at low-irradiation (1000 kWh/(m^2·yr)), with corresponding quality-adjusted energy return on investment (EROIPE-eq) values ranging from over 60 to ~10. If you want to see other publications on the same topic, try hitting Google Scholar with search terms "photovoltaic" "life cycle" "energy payback". For the most accurate results, restrict your search to recent years. Manufacturing processes are revised rapidly and studies from the turn of the millennium are now badly obsolete. (Though even in 1990 PV systems were net energy positive on average; the worry that PV system manufacturing consumes more energy than the lifetime output appears to be a holdover from the very early (1970s) days of terrestrial PV systems.)

ars 10y ago
I'm skeptical of your numbers. With such a quick payback time you'd expect to see solar power going up like crazy. (Like how wind was being installed quite fast for a while - although only in the best spots.) Except you don't, you just see limited installations here and there. If solar power has such a quick payback period why aren't more investment groups funding it? Are the panels not available in sufficient quantity?
- brokencode 10y ago
  The main problem with solar is that it is not a full replacement for current power plants, since it does not produce power at all times. Until we have the capacity to store energy to use at night and on cloudy days, solar will be limited in potential. I think his numbers didn't take into consideration the expensive backup power plant that you have to have ready even if you have adequate solar capacity.
- philipkglass 10y ago
  Solar power is going up like crazy. The US just had its highest-ever quarterly solar installation rate, up 191% over Q3 2015: https://www.greentechmedia.com/articles/read/in-its-largest-quarter-ever-us-solar-market-saw-nearly-2-mw-of-pv-installed https://www.greentechmedia.com/articles/read/in-its-largest-... Global installations for 2016 are also on track to set a new record, surpassing 2015 installations by 48%: https://cleantechnica.com/2016/11/30/global-solar-installations-reach-76-gw-2016-mercom/ https://cleantechnica.com/2016/11/30/global-solar-installati... And despite these records, the manufacturing side of the industry is currently demand-constrained rather than supply-constrained. When you say you there's just "limited installations here and there," are you estimating from whatever you personally see in your local area?
- beefield 10y ago
  Energy payback time is a different concept than money payback time. Investors are interested in the latter, First one is a rudimentary requirement for long term feasibility without subsidies. Also, global solar is going up like crazy. Global sustained growth rate of around 40% is crazy fast. If that keeps on for a bit more than ten years, 100% of current global electricity demand is covered by solar. Just for comparison, there exists no two subsequent full years of iPhone production where Apple would have managed to achieve 100% growth.
- mikekchar 10y ago
  I have to echo the statement that PV is going up like crazy -- at least where I live. Admittedly I'm in one of the sunniest places in Japan (and at 34 degrees latitude to boot). They are clear cutting forest to put up installations everywhere. Virtually every single apartment building already has solar panels on top of them. Every house builder offers solar panels on new houses and while I've seen a couple of new houses without them, they are definitely the exception. Every electronics store sells solar panels and usually it is the thing that they are pushing hardest (weird to see huge solar panel displays next to the refigerators and TVs). I've done the math and with the price of electricity we pay here, it is a complete no brainer to get solar panels. If I lived in a house, I wouldn't even think twice.

epistasis 10y ago

The term is EROI (energy returned on energy invested), for renewables its currently roughly equivalent to fossil fuels and getting higher as the technology improves. As oil and natural gas get more expensive and energy intensive to extract, their EROI is going down.

chillydawg 10y ago
Going down from a fantastically high return to a slightly less fantastically high return.
- epistasis 10y ago
  Yes, but it's going to continue to go down. According to Wikipedia [1] EROI Fuel ---- ---- 35.0 Oil imports 1990 18.0 Oil imports 2005 12.0 Oil imports 2007 6.8 Photovoltaic (wikipedia) 14.4 Photovoltaic [2] (from recent analysis of post-2008 data) The trend lines are clear and stark. The technologies for photovoltaic, wind turbines, and for fossil fuel extraction are all changing. It's certainly not the case that fossil fuels will disappear, but over the coming decades the sector will shrink dramatically due to market forces; investments will plummet. And once you start looking at the slow and steady pace of improvement in storage technologies, it looks highly possible that around 2025-2030, only specialized energy applications ever make new investments in fossil fuel based technologies. And that's without accounting for the negative externalities that fossil fuel users (all of us) make everybody else subsidize. Existing infrastructure will continue as long as its economical, of course, but there's most definitely a huge turning point around the corner in energy technology. [1] https://en.wikipedia.org/wiki/Energy_returned_on_energy_invested https://en.wikipedia.org/wiki/Energy_returned_on_energy_inve... [2] https://www.researchgate.net/publication/311170056_Solar-PV_energy_payback_and_net_energy_Meta-assessment_of_study_quality_reproducibility_and_results_harmonization https://www.researchgate.net/publication/311170056_Solar-PV_...
  - ZeroGravitas 10y ago
    I believe those EROI numbers also don't include converting the energy into the useful output that you need and so are a a pointless apple-to-oranges comparison PV output is electricity already, to get electricity from coal you'd need to throw away 2/3rds of the energy as heat, about half for gas, reducing their EROI by that factor in a correct comparison. So if it's electricity you want then PV is already winning over fossil fuels I think. Similarly, for powering cars with gasoline they're not as efficient in converting that energy "well-to-wheel" as EVs, as the losses in battery storage and electric motors are much smaller, giving you a "miles driven return on energy input" measure about 3x higher for a PV charged car vs ICE. You can avoid the generation loss on natural gas by piping to the home and burning it directly for heat in areas that need heat, getting close to 100% efficiency with modern central heating systems, but then in those same situations you can use an electric heat pump and get 3-500% efficiency, since you're only moving the heat around, not generating it.

intrasight 10y ago

Was also discussed (more in terms of carbon footprint) in The Economist this week: http://www.economist.com/news/science-and-technology/21711301-new-paper-may-have-answer-how-clean-solar-power http://www.economist.com/news/science-and-technology/2171130...

jaclaz 10y ago

Don't forget the costs to dispose of them once they are not producing energy (or enough energy), typically after 15 to 20 years, and the overcosts for replacements due to "natural" events, like hailstorms.

smaddox 10y ago
There could actually be an interesting secondary market for solar cell recycling. My understanding is that the primary degredation is due to the contacts, which could likely be reapplied or annealed in order to reach their original efficiency.