> And that is why it is a huge problem for the power companies
It is a problem, but not necessarily in the way you may be thinking. Peak residential power usage is in the evening when solar isn't available. Power companies therefore end up spinning down coal and natural gas during peak solar, then just spinning them back up again as the sun begins to set. [1]
So you haven't replaced the coal and natural gas plants, you're just running them less. This results in higher overall costs, because you pay $$$ to build huge plants then just let them sit most of the day, which results in higher per-watt cost of non-solar power because the infrastructure and maintenance is no longer amortized over whole-day usage.
[1] My friend, a manager of 30 years at a huge mid-west power company
It is a problem, but not necessarily in the way you may be thinking. Peak residential power usage is in the evening when solar isn't available. Power companies therefore end up spinning down coal and natural gas during peak solar, then just spinning them back up again as the sun begins to set. [1]
So you haven't replaced the coal and natural gas plants, you're just running them less. This results in higher overall costs, because you pay $$$ to build huge plants then just let them sit most of the day, which results in higher per-watt cost of non-solar power because the infrastructure and maintenance is no longer amortized over whole-day usage.
[1] My friend, a manager of 30 years at a huge mid-west power company