From Science Mag on the progress of solar technology:
This month, officials in Los Angeles, California, are expected to approve a deal that would make solar power cheaper than ever while also addressing its chief flaw: It works only when the sun shines. The deal calls for a huge solar farm backed up by one of the world’s largest batteries. It would provide 7% of the city’s electricity beginning in 2023 at a cost of 1.997 cents per kilowatt hour (kWh) for the solar power and 1.3 cents per kWh for the battery. That’s cheaper than any power generated with fossil fuel.
This is the power of technology cost curves. Incremental improvements slowly drive down costs of new technology - often while incumbents write off new entrants as not being good/fast/cheap enough. Soon after better tech becomes cheaper than the alternative, change happens fast and incumbents get displaced.