Someday some wizard will develop a chemistry breakthrough that will do for storage of electricity what horizontal drilling and hydraulic fracturing has done for oil and gas production.
In the meantime, the cost for battery storage of electricity is staggering.
5/22/17 – Wall Street Journal – The Race to Build a Better Big Battery – The unreliable intermittent nature of solar power is a massive problem blocking the way of solar being a viable substitute for fossil fuels.
Major efforts are underway to figure out some way to store electricity on an industrial scale.
One cited experiment is being run by Greet Mountain Power. They have a 7,722 panel solar plant which has a theoretical capacity of providing the power to 2,000 homes when the weather conditions are right.