Cool you are doing some analysis on this, but I think it ignores the likely effects of inflation on all things, especially since that inflation itself is caused by a fundamental mathematical difference between solar energy and all others. Specifically, solar is something that when we use, adds to economic capital, whilst use of any other kind of energy subtracts from economic capital.
Notice also in this context, which is the one that matters, "Chepest" has to be thought of as cheapest to the planet. Anying that comes at cost to the planet ultimately has to become cost to us.
Might not seem a big deal, but this has to be an exponential effect, which is becoming more acute with both time, and the proportion of energy consumed coming from solar.
In other words, there is no way the economy as is, with all money issued as debt, will stretch to it, it is already approaching breaking point.
Notice profitability itself is something depending entirely on energy extracted from Earth, ie Mathematically negative energy, and energy extracted from Earth, of any kind, is the thing unsustainable, even by thermodynamics; conversion of matter or other stored energy to anything other than what nature already created with it, has to result in temperature rise.
Notice how profitability itself is becoming more and more difficult, with more and more buinesses going under, due to lack of profitability, this will not stop, until the fundamental reason for it stops, which is energy availabilty underlying it all. The fact is we are nearing the end of usable energy extracted from earth, in any form, nuclear, oil, gas, even wind, actually.
The exact opposite is true of use of solar, use of solar for anything other than the heating effect it normally has on Earth, has to result in reduction of temperature.
The only way out, of this existential energy cul de sac we are in, is to begin issuing money reflecting economic product created from solar, because money issued as debt can't monetise solar, since solar energy is something received with nothing asked in return (The sun, the source of it, asks nothing for it)
The amounts that need to be issued, to counter this inflation are not small, we are talking a generous UBI for all people.
Inflation ignored, will result in continued loss of purchasing power eventually threatening all capability to fix things by installation of appropriate solar infrastructure.
Notice all of this above is observation, from actual utilities and population data, not theory. If you doubt any of it, I invite you to comment on the article linked at the bottom of this comment.
The future solution which looks most likely to meet the above change of circumstances is domestic and community solar, backed by hydrogen.
This will address water circulation, food shortages (See "Solein"), whilst replacing all fossil fuel use by hydrogen, providing hydrogen refuelling literallly on every street corner for vehicles converted or designed to run on hydrogen, enabling even aviation to fly on hydrogen.
The issue of significant funds to all people as UBI will result in massively boosting domestic and community solar. All governments, all factories, all companies, all people will be motivated to do this by the wish to maximise future stipend.
