I commend what looks like a slight change of direction in your writing, away from idealism towards acceptance that there might just be limits to the human endeavor. Staying with your tree example: the tree uses solar energy AND minerals from the soil to replace old leaves with new ones. If the energy balance is positive, and the nutrients in the soil are there, it can do it for quite a long time. In our case with photovoltaics however neither the technical means, nor the energy balance, or the materials are there. Technical means: there are currently 0 photovoltaic sites which are capable to reproduce even one of their lost panels. These panels require mining, smelting, melting, manufacturing - all powered by fossil fuels for simple technical reasons. Our apparent ability to replace panels at low cost, is an illusion made available by low cost fuels, cheap labor, and environmental destruction - far away from Western eyes. (Notice, how trees doesn't require any of these processes.) Energy balance: this where - as you have mentioned - we need to calculate with the ROI of individual panels. How many kW-s they generate through their limited lifetime? I presume we get a finite number. Thus we need to shoot for getting this number as high as possible at the lowest energy cost possible. Hence EROEI. Applying your methodology to oil, would be equal to calculate all wells, vs all oil ever extracted. Yes, it is finite number, but as soon as you run out of critical materials, due to the ever increasing energy requirement to get them (thanks to depletion of rich reserves), we will eventually hit a maximum limit of solar panels ever to be built on this planet as well. Sorry, I still see no other option to harness solar energy than to use plants (trees and crops) - where these technical questions were solved millions of years ago, and kept working by an immensely complex ecosystems of fungi, bacteria, insects, birds, a working climate and all the rest. Why try to replicate this, when we could return to use them? Because we are in overshoot and there is no other option for us than to keep growing till we crash? We need to address our consumption problem (consuming one time resources and eating up all living things at an unsustainable rate) - in my view this includes oil, solar panels, burgers and everything.