I am not sure who it might have been who talked about it originally, I suspect it probably goes back to ancient Greece maybe even Egypt, but lets credit your grandad for putting it your head, hence it is here now.
(My own grandad put aliens in my head, but that's another story :)
The work I've done on this (I am a long practicing Systems Engineer), has been towards integrating money with it, which is what seems to be needing to be done, to complete the connection between us and the energy of the sun, effectively plugging us in to the mains power source in the sky.
After this is done, we will be working as a species like plants, issuing money in direct response to "New Sun" Joules, pushing that energy plus some spare to all people, adding value to Earth by everything we do with it, instead of subtracting from Earth by everything we did by energy extracted ("Old Sun"!) from Earth.
Our net activity has been one of removal of things created by nature, thus also removing Joules from Earth. by that we've run up an energy deficit, driven by the mechanism of money-as-debt, since all promises to pay have to end up as promises to do the work of extraction.
Having the solar facilities installed is great, but still considered only in terms of profit, which actually has no meaning when the energy being received is endless. To fully value it, money has to be issued on the product created from it, but so far that has not been done, in fact the utiilies industrey literally tries to ignore it, and even acuse anyone who points it out as "Dreaming", but it is undeniable, and the penalty for breaking this particular rule of nature, as you indicate, is that we burn.
But besides that, and this is the thing that has to make all the difference, much quicker than they realise, is inflation. This is inevitable and uncontrollable as long as the necessary solar product coming in, still steadily scaling up, continues to take over the business of public energy supply, and no money is issued to ennumerate the economy resulting from solar product put to use.
Your view of Old and New sun is something I've found realy difficult trying to get across to even seasoned scientists, and definitely economists, who want to see and hear everything only in terms of their domain, but this thing is multidisciplinary, never covered previously in science, believe it or not, probably because pretty much all science around this subject is funded by the companies still trying to sell us million years old sun, even if they don't realise it, by also selling us solar panels at profits paid to VC funded companies, which ties us into further extraction.
So your terms of Old and New sun are as good as any, I would say.
The breakthrough will come when money issued against solar product begins to fund manufacture of panels and other solar collection and processing infrastructure producing things like hydrogen, and even food (See "Solein")
Anyway, I can only scratch the surface in a response like this, sorry it already looks like war and peace.
Here is some of the latest maths showing graphically what it means to us:
