It's about return on energy. Fossil fuels return 20x what you invest it's essentially free energy.

(edit: roughly, this translates to how many people are free to do things with the work of one, if every person lives alone, it's 1, if each person has a personal slave/robot, it's around 2, we want to stay well above 2. Modern society has 19 people doing all sorts of non-survival things for each one farming and collecting resources because fossil is so "cheap")

Renewables can reach 5-10 at best, which is not so bad (medieval was around 1.3, pre-industrial with slavery was around 1.8), so you can do it, but it will have to reshape society, which will be fine, if we know what we're doing or can at least imagine what we are aiming for to avoid disappointment. It's hard to be utopian going backwards.

This whole debate started with carbon footprints and carbon pricong, because I believe that creating a market can help the less virtuous among us to use their greed to help solve the problem of public consent in a consumerist society without devolving into a dictatorship.

But yea, let's aim for that energy return of say... 7 and try to imagine what such a society would look like. A return to slower shipping by sail again...more solar boilers for all hot water...solar desalination...peak-solar hydrogen for fertilizers and airplanes...more compact cities with mass transit and bikes, lots of working from home, more fixing things DIY...a return from cities to the countryside and decentralisation would help, but only if those communities were more self-sustained and local, with 2x more power to farming, mining and wind/solar communities (meaning potentially smaller countries)...now I could describe all the potential setbacks of all of those points, but I won't, because this is solarpunk and we need more imagining of what things are going to be like when we succeed...not so much the year 500 :)