> For example, suppose we had single 1KW solar panel, and the panel had a very low ERoEI of 4 (which is certainly an underestimate [1]). Even if you increased the ERoEI from the very low value of 4, all the way up to to infinity, so that no energy was required to replace that solar panel, it would make little difference--it would increase the amount of NET energy obtained by only 25%. On the other hand, if you could build 3 such solar panels, instead of 1, then you would triple the net energy obtained. In this case, building two more solar panels had 12x greater effect than increasing the ERoEI to infinity.
I get what you are saying, but I'm not sure I would go so far as to say it is "BS". Here is a different pov:
You are about to build 1 solar panel. Where should you put it it? Somewhere with a lot of sun (EROEI of 1:10) or somewhere with a little sun (ERORI of 1:4). All else being equal, you would put it where you get more sun. Of course, as you build more and more panels, you ask yourself "when should I stop", and the answer is "when it costs just as much to install as I get back" (ERORI 1:1)
A separate calculation is "I have invented a more efficient solar panel! Should I replace existing solar panels?"
Thats not a real problem, nor a real solution. If you have a panel already built, the energy input is a sunk cost. It has no relevance to where you put the panel to maximise its output, you only care about the E part, not the ROEI part which is the hard bit to calculate. And no-one used it that way anyway.
Zooming way out, you also don't stop building panels on a global scale when EROEI reaches 1.0000001. You stop when there's an opportunity cost. Can that same input be used for something more valuable? Then stop building panels, even if their EROEI is massive. We're not phasing out fossil fuels because their EROEI is below one, for example.
Similarly, We have plenty of different solar panel designs, with different EROEI's. We're not building the ones with the highest score on this metric, and we shouldn't, it's not as important as other things like mass scale manufacturing capability. Especially because what we are building generates electrical energy. If energy is the deciding factor we can make some, by building solar panels.
I used BS specifically because it is a real thing that you can actually measure. Its just that it was only ever found to be useful to people who were making most of their facts up anyway. Its not a lie if the person saying it doesn't care if its true or false, its just BS.
I 1:9 ratio of energy-in to energy-out is pretty good!