It sounds like your issue is with capitalism, not with renewable energy. Luckily, we have plenty of examples of aspects of society that have been deemed too important to leave purely to market forces. In fact, electricity generation is already (mostly) one of them.

As solar and batteries become even cheaper (we're already at the point where they're cheaper than anything else) we can just choose to overbuild capacity and turn down/off whatever other generation isn't necessary at any given time. Utilities already have to predict grid usage based on weather and all sorts of other factors, so it's not like this isn't something that isn't already happening.