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> 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 physica

> 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...
- arcticbull 4y ago
  I never said anything about coal, and I updated the degradation numbers per your suggestion, but the degradation numbers themselves come from NREL. I think you're confusing the derating due to temperature with degradation. They are additive.
  - dpierce9 4y ago
    Panel temps go up and down depending on time, date, location, and weather. On cool, sunny spring days you can see panels produce more than they are rated. You can’t simply apply a fixed worst-case derate for all time to all panels regardless of installation details. Further, the derates are not additive, they are multiplicative. (A a 20% panel which has degraded in lab efficiency by 10% operating at 90% thermal efficiency is running at 16.2% efficient compared to 18% for a non-degraded panel). Nothing you have said, however, addresses my first and principal point which is that operational efficiency has a different meaning for solar when compared to anything that has non-free inputs. Efficiency is outputs/inputs. One way to look at it is [energy out]/[energy hitting panel]. That is 20% for a solar plant, 45% for an nuclear analogue. Another, financial way is [value of output]/[cost of inputs]. This is infinity for solar setting aside fixed/financing costs and quite finite for nuclear using the same assumptions.
    - arcticbull 4y ago
      A device that's 15% efficient is inherently more wasteful than a device that's 100% efficient, right? Therefore we're wasting something. That thing isn't input fuel, it's the materials used to build the device, and manage its lifecycle. That doesn't mean it's free - it just means we're considering different inputs. Total efficiency here is the sum of all inputs over outputs. For solar panels that's land use, that's glass, silicon, plastic, PCBs, etc - in addition to the sun. Otherwise, in your model, a panel that's 100% efficient is inherently the same as one 15% efficient. In your model, a battery is infinitely efficient - after all it has no inputs, only outputs! Once you get to that point your model needs to be adjusted.
      - 4y ago
ZetaZero 4y ago
> to generate comparable amounts of power to conventional sources requires huge amounts of landmass. It would take about 0.01% of the US land area to generate all the electricity we need. Meanwhile we use 30% (over 1000x) to grow food. And if we prioritize solar on rooftops and deserts, we really are not using any useful land.

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...

arcticbull 4y ago
I never said anything about coal, and I updated the degradation numbers per your suggestion, but the degradation numbers themselves come from NREL. I think you're confusing the derating due to temperature with degradation. They are additive.
- dpierce9 4y ago
  Panel temps go up and down depending on time, date, location, and weather. On cool, sunny spring days you can see panels produce more than they are rated. You can’t simply apply a fixed worst-case derate for all time to all panels regardless of installation details. Further, the derates are not additive, they are multiplicative. (A a 20% panel which has degraded in lab efficiency by 10% operating at 90% thermal efficiency is running at 16.2% efficient compared to 18% for a non-degraded panel). Nothing you have said, however, addresses my first and principal point which is that operational efficiency has a different meaning for solar when compared to anything that has non-free inputs. Efficiency is outputs/inputs. One way to look at it is [energy out]/[energy hitting panel]. That is 20% for a solar plant, 45% for an nuclear analogue. Another, financial way is [value of output]/[cost of inputs]. This is infinity for solar setting aside fixed/financing costs and quite finite for nuclear using the same assumptions.
  - arcticbull 4y ago
    A device that's 15% efficient is inherently more wasteful than a device that's 100% efficient, right? Therefore we're wasting something. That thing isn't input fuel, it's the materials used to build the device, and manage its lifecycle. That doesn't mean it's free - it just means we're considering different inputs. Total efficiency here is the sum of all inputs over outputs. For solar panels that's land use, that's glass, silicon, plastic, PCBs, etc - in addition to the sun. Otherwise, in your model, a panel that's 100% efficient is inherently the same as one 15% efficient. In your model, a battery is infinitely efficient - after all it has no inputs, only outputs! Once you get to that point your model needs to be adjusted.
    - 4y ago

ZetaZero 4y ago

> to generate comparable amounts of power to conventional sources requires huge amounts of landmass. It would take about 0.01% of the US land area to generate all the electricity we need. Meanwhile we use 30% (over 1000x) to grow food. And if we prioritize solar on rooftops and deserts, we really are not using any useful land.