The problem has always simply been that power generation is centralized, concentrated in a few hands.  Large power plants producing it, and large elaborate distribution lines to deliver it.  This is not how it could have been, but a few decided it should be this way, for obvious reasons, for the sake of profit.

But things have been slowly changing since solar panels have been mass produced, getting cheaper, and gaining in efficiencies.  With decentralized power ( ... decentralized, funny aye  )  there would be no need for large power plants or expansive distribution networks.  At worst there may still be a need for small local power distribution centers for emergencies, but nothing more.  ... The cost would solely be the production, and installation of the solar panel hardware, and the energy free.  There has always been animosity from those that wish to profit from centralized power, and this will continue until the end.  The end being fully decentralized power.

Throughout history energy has been commoditized, but in this modern age this is no longer necessary.   In this universe, besides space and time, energy is the most abundant thing.  The water we drink, or the oxygen we breathe is far more rare than energy, and yet we pay each month for power.

Nuclear power, fission or fusion, when developed enough, and made small enough will be useful for areas that have little to no access to the sun.  Like maybe Pluto.     Or, interstellar travel.

I don't see free power as a threat to bitcoin.  Free power may seem to make the cost of producing btc less, but then any extra cash a miner has would be used for more mining hardware, increasing btc's difficulty, which increases its cost of production, which helps to increase its price, and so on.