Comment by slow_typist | Hacker News Reader

Comment by slow_typist | Hacker News Reader

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585 kWh/m^2 median energy consumption for production according to a 2013 study cited on the Wikipedia article on energy return on investment. 440 W panel has about 2 m^2. It is probably a tad better now, because lower mass of silicon per meter squared. That translates to roughly 2.5 years of energy payback time in Germany under good conditions (azimuth SE to SW and elevation about 30 to 60 degrees, no shadow). Give a few extra months for the inverter and system losses. If you want to know exactly there are commercial databases used for LCA calculations.

The carbon emissions depend on the energy mix of the supply chain (which is mostly in China, since Germany totally butchered domestic production). And the total climate effect is amplified by other emissions (leaking of technical gases in silicon production? But now I am way out of my field of expertise.)

OTOH hand to calculate the offset of emissions you need to know what is going on in the grid. If windmills are shut down around noon to make room for PV, the offset is zero.

Wow that is pretty good, lines up pretty nicely with the approx monetary break even as well. Impressive!

Wonder if there is anything that can be done to lengthen the life of the panel as much as possible. I've read elsewhere that solar panels have a theoretical lifespan of 25 years with the panels slowly degrading and not failing all at once. I dont know if these specific panels are different but I wonder if the panels are kept clean or something if that would maximize the lifespan?

Degradation is more or less solved. Producers guarantee a maximum of .4 % power degradation per year for 25 or even 30 years. That may be offset buy rising energy costs alone. May be not if someone manages to producer cheaper batteries.

Right now owners of older rooftop photovoltaics in Germany swap functioning modules for newer ones with better efficiency.

Even if some small percentage of older modules fails it is probably not the fault of the cells but of connections in the module due to moisture. It is a system. In theory you can take the cells and build new modules. But that is too expensive compared to buying new modules.

Wonder of those old panels can be sold or shipped to developing countries if no one in the west wants them. It will be like old mercedes, they can be rusted to the core, they still end up having a second, third and fourth life in Africa.

Solar is one of those magical technologies that seems to keep giving in different ways.

> If windmills are shut down around noon to make room for PV, the offset is zero.

Very important point that is often ignored.

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