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> How green is solar panel production, BTW? The term "green" is probably too vague to answer that question. However, I once read (a long time ago, so no link)

by dmfdmf 16y ago

> How green is solar panel production, BTW? The term "green" is probably too vague to answer that question. However, I once read (a long time ago, so no link) an article on some research that reported that EV solar was net-energy negative, i.e., if you add up all the energy that went into producing EV solar panels and subtracted the energy output over its expected lifetime it was negative. This is not true of hot-water type solar just EV solar panels. Of course the conclusion rested on numerous assumptions but they used conservative assumptions and argued that EV is not an energy source and would need some wild breakthroughs in reducing the energy costs to manufacture or a huge jump in energy output efficiency neither of which, as far as I know, has happened. Edit: I got that reversed, Energy Output - Energy to make < 0

Retric 16y ago
Times change, 50,000Hz Computers used to be top of the line and cost thousands of dollars, but try selling such things today at those prices. The value of electricity produced over a modern solar cell’s lifetime > cost of that solar cell today so clearly they take less energy to produce than it takes to make. However, ROI is more than just getting more money back than something costs the payback time is important. PS: Granted, Ultra high efficiency solar cells built for the space program still cost a lot. However, they are producing energy in space so the incentives change.
- rbanffy 16y ago
  dmfdmf's point is that it takes more energy to make a solar cell than it will ever produce during its lifetime. I am not sure his numbers are current (he made the disclaimer), but it has nothing to do with energy pricing. My worry is not whether photo-voltaic is net-positive, but whether the production actually reduces pollution. For what I know, they are very close cousins of computer chips and those factories were not particularly "green".
  - Retric 16y ago
    Energy is a complex topic, so calculating the actual energy costs to produce something is hard because different forms of energy have different value. EX: heat pumps don't generate energy even though they can output more BTU's than an electric heater. However, electricity cost to generate other types of energy works as a shortcut to a lot of this stuff. So generally if something costs X$ to manufacture it takes less energy than X$ worth of electricity. As to being green; PV is not exactly a single technology with a single type of environmental impact. Assuming you recycle the cells, PV can have a very environmentally friendly footprint, but the factory must also take care to avoid a wide range of pollution. PS: It’s hard to talk about energy without using enthalpy, entropy, and other thermodynamic concepts. If my point is not clear I can try a more detailed explanation.

by dmfdmf 16y ago

Retric 16y ago

Times change, 50,000Hz Computers used to be top of the line and cost thousands of dollars, but try selling such things today at those prices. The value of electricity produced over a modern solar cell’s lifetime > cost of that solar cell today so clearly they take less energy to produce than it takes to make. However, ROI is more than just getting more money back than something costs the payback time is important. PS: Granted, Ultra high efficiency solar cells built for the space program still cost a lot. However, they are producing energy in space so the incentives change.

rbanffy 16y ago
dmfdmf's point is that it takes more energy to make a solar cell than it will ever produce during its lifetime. I am not sure his numbers are current (he made the disclaimer), but it has nothing to do with energy pricing. My worry is not whether photo-voltaic is net-positive, but whether the production actually reduces pollution. For what I know, they are very close cousins of computer chips and those factories were not particularly "green".
- Retric 16y ago
  Energy is a complex topic, so calculating the actual energy costs to produce something is hard because different forms of energy have different value. EX: heat pumps don't generate energy even though they can output more BTU's than an electric heater. However, electricity cost to generate other types of energy works as a shortcut to a lot of this stuff. So generally if something costs X$ to manufacture it takes less energy than X$ worth of electricity. As to being green; PV is not exactly a single technology with a single type of environmental impact. Assuming you recycle the cells, PV can have a very environmentally friendly footprint, but the factory must also take care to avoid a wide range of pollution. PS: It’s hard to talk about energy without using enthalpy, entropy, and other thermodynamic concepts. If my point is not clear I can try a more detailed explanation.