Solar electricity is generated when the sun is up and the sky is clear. But electricity is needed during the night and on cloudy days. So a solar electricity plant must be accompanied by a backup plant. A combined-cycle natural gas plant can be purchased at a capital cost of approximately $1,000 per kilowatt of output capability. Depending on the percent utilization, electricity can be generated in the range of 4 cents to 6 cents per KWH. The natural gas fuel at current prices costs about 3 cents per KWH. Capital costs distributed over the 30-year life of the plant are in the range of 1-3 cents per KWH depending on percent utilization. The percent utilization can be has high as 90%.
The bottom line is that the only saving from a solar electricity plant is the fuel not burned when the solar is working. Most likely, the fuel is natural gas. But the maintenance of the solar plant costs about the same per KWH as the fuel for a natural gas plant. It most cases, it probably makes sense to bulldoze a solar plant and use the backup natural gas plant.
Believers in global warming alarmism will probably claim that it is worth paying 5 times more for electricity in order to reduce CO2 emissions. But if they are really concerned about CO2, the obvious solution is CO2-free nuclear power, which is far cheaper and more practical than solar.
Wind power is the other renewable energy. The capital cost of building wind farms is less than solar, and the utilization factor may be higher in favorable locations. But, at best, wind energy costs 2-3 times more per KWH than conventional energy. There are doubts about the useful life of wind turbines and many population centers have no suitable wind energy sites near enough to economically transport the power.