4 ms·

They're not efficient at turning sunlight into power - somewhere around 20% depending on the technology, which continues to improve albeit slowly. This efficien

They're not efficient at turning sunlight into power - somewhere around 20% depending on the technology, which continues to improve albeit slowly. This efficiency goes down about 2.5% in the first year and another [edit](0.5%-1%) in each subsequent year [1]. These numbers are all at 25C, which is significantly lower than a black solar panel is going to be out in the sun - which reduces its efficiency a further 10-25%. [2] So typical 20% efficiency solar panel at 45C in year 2 is already starting at 17.5% efficiency, and by year 10 is down to just [edit](15%) efficiency. And then while lower temperatures do improve efficiency, they tend to happen in higher latitudes which get less sunlight to begin with. 60% of Ontario's power (about half of Canada by population) comes from just 3 nuclear plants (Bruce, Darlington and Pickering). Replacing them with solar panels would cover an area the size of the entire greater Toronto area in silicon and plastic, give or take. [3] And it would need to be replaced every 20 years. Solar and wind play a role, but nuclear does too. Edit: Corrected degradation amount per dpierce9 [1] https://energyeducation.ca/encyclopedia/Solar_cell_efficiency https://energyeducation.ca/encyclopedia/Solar_cell_efficienc... [2] https://www.cleanenergyreviews.info/blog/most-efficient-solar-panels https://www.cleanenergyreviews.info/blog/most-efficient-sola... [3] https://www.cer-rec.gc.ca/en/data-analysis/energy-markets/provincial-territorial-energy-profiles/provincial-territorial-energy-profiles-ontario.html https://www.cer-rec.gc.ca/en/data-analysis/energy-markets/pr...

dpierce9 4y ago
This is some bad reasoning. Solar efficiency is very different from say engine efficiency. A very efficient combustion engine is 35% efficient meaning it wastes 65% of the energy in the input fuel. Solar panels don’t waste sunlight and have no input costs. Rooftop solar turns 20% of something that would have been 100% wasted into high grade energy. A very efficient coal power plant is 45% efficient before transmission losses. That means more than half the energy in the coal is wasted. Solar wastes nothing. Your numbers on solar panel degradation are also incorrect based on my experience in the industry. They do degrade but not at that at 7+% per year for ten years. Edit: corrected degradation amount
- arcticbull 4y ago
  > Solar panels don’t waste sunlight and have no input costs. Not exactly, the point is that building and installing solar panels consumes resources and physical space. A solar plant with 100% efficient panels is 1/10th the size of today's solar plant, and as I mentioned, to generate comparable amounts of power to conventional sources requires huge amounts of landmass. Plus input materials. And it has to be replaced every 20 years. > Rooftop solar turns 20% of something that would have been 100% wasted into high grade energy. Not 20%, right, closer to 15%. Rooftop solar also kills about 10X as many people per generated TWh (0.44-0.83 people per TWh) as compared to nuclear power (0.04 people per TWh) - due to installation. [1] I'm not advocating for coal of course, but it's wrong to say solar wastes nothing. There's input materials, plastics, silicon - all sorts of toxic chemicals - and generates tons and tons of e-waste that we don't really have a plan for right now. [2] > Your numbers on solar panel degradation are also incorrect based on my experience in the industry. They do degrade but not at that at 2% per year for ten years. As I mentioned, the degradation rate is highest in the first year, I said 2.5%, but then it drops off to about 0.5% in subsequent years. The data comes from an NREL analytical review. [3] NOTE: I edited the number to more generously assume the 0.5%-1% degradation was not in percent efficiency but rather in percent capacity - which is 1/5th as much, to your point. [1] https://www.nextbigfuture.com/2011/03/deaths-per-twh-by-energy-source.html https://www.nextbigfuture.com/2011/03/deaths-per-twh-by-ener... [2] https://www.wired.com/story/solar-panels-are-starting-to-die-leaving-behind-toxic-trash/ https://www.wired.com/story/solar-panels-are-starting-to-die... [3] https://www.nrel.gov/docs/fy12osti/51664.pdf https://www.nrel.gov/docs/fy12osti/51664.pdf
  - dpierce9 4y ago
    Not sure why I am responding since you moved the goal posts from operating efficiency to lifecycle efficiency but even there you are wrong. To your point re: land use, this is why I said rooftop solar. The roof is already there, the structure is already there, there is zero additional land use and very little opportunity cost for the space. Further, the land use for coal is much broader than the plant area because of mining, transit, and waste heat management. There was a recent post on HN comparing total land usage by prime mover. Solar is only deadlier per unit than coal if you ignore substantial local health effects that aren’t priced in.[0] Your implied rate of degradation to go from 20-10 is more than 7%. Even 15-10 is more than 2.5% and again that is an absurd number that contradicts observed performance. You misunderstand what degradation means in this context, to your point. [0] https://surgery.duke.edu/news/despite-studies-health-effects-coal-burning-power-plants-remain-unknown https://surgery.duke.edu/news/despite-studies-health-effects...

dpierce9 4y ago

This is some bad reasoning. Solar efficiency is very different from say engine efficiency. A very efficient combustion engine is 35% efficient meaning it wastes 65% of the energy in the input fuel. Solar panels don’t waste sunlight and have no input costs. Rooftop solar turns 20% of something that would have been 100% wasted into high grade energy. A very efficient coal power plant is 45% efficient before transmission losses. That means more than half the energy in the coal is wasted. Solar wastes nothing. Your numbers on solar panel degradation are also incorrect based on my experience in the industry. They do degrade but not at that at 7+% per year for ten years. Edit: corrected degradation amount

arcticbull 4y ago
> Solar panels don’t waste sunlight and have no input costs. Not exactly, the point is that building and installing solar panels consumes resources and physical space. A solar plant with 100% efficient panels is 1/10th the size of today's solar plant, and as I mentioned, to generate comparable amounts of power to conventional sources requires huge amounts of landmass. Plus input materials. And it has to be replaced every 20 years. > Rooftop solar turns 20% of something that would have been 100% wasted into high grade energy. Not 20%, right, closer to 15%. Rooftop solar also kills about 10X as many people per generated TWh (0.44-0.83 people per TWh) as compared to nuclear power (0.04 people per TWh) - due to installation. [1] I'm not advocating for coal of course, but it's wrong to say solar wastes nothing. There's input materials, plastics, silicon - all sorts of toxic chemicals - and generates tons and tons of e-waste that we don't really have a plan for right now. [2] > Your numbers on solar panel degradation are also incorrect based on my experience in the industry. They do degrade but not at that at 2% per year for ten years. As I mentioned, the degradation rate is highest in the first year, I said 2.5%, but then it drops off to about 0.5% in subsequent years. The data comes from an NREL analytical review. [3] NOTE: I edited the number to more generously assume the 0.5%-1% degradation was not in percent efficiency but rather in percent capacity - which is 1/5th as much, to your point. [1] https://www.nextbigfuture.com/2011/03/deaths-per-twh-by-energy-source.html https://www.nextbigfuture.com/2011/03/deaths-per-twh-by-ener... [2] https://www.wired.com/story/solar-panels-are-starting-to-die-leaving-behind-toxic-trash/ https://www.wired.com/story/solar-panels-are-starting-to-die... [3] https://www.nrel.gov/docs/fy12osti/51664.pdf https://www.nrel.gov/docs/fy12osti/51664.pdf
- dpierce9 4y ago
  Not sure why I am responding since you moved the goal posts from operating efficiency to lifecycle efficiency but even there you are wrong. To your point re: land use, this is why I said rooftop solar. The roof is already there, the structure is already there, there is zero additional land use and very little opportunity cost for the space. Further, the land use for coal is much broader than the plant area because of mining, transit, and waste heat management. There was a recent post on HN comparing total land usage by prime mover. Solar is only deadlier per unit than coal if you ignore substantial local health effects that aren’t priced in.[0] Your implied rate of degradation to go from 20-10 is more than 7%. Even 15-10 is more than 2.5% and again that is an absurd number that contradicts observed performance. You misunderstand what degradation means in this context, to your point. [0] https://surgery.duke.edu/news/despite-studies-health-effects-coal-burning-power-plants-remain-unknown https://surgery.duke.edu/news/despite-studies-health-effects...