The cost of electricity from solar has dropped by 85% since 2010, and it is now among the cheapest sources of electricity in many places across the United States. Utility-scale renewable energy prices are now significantly below those for coal and gas generation, and they are less than half the cost of nuclear. Building new utility-scale solar energy generation is even cheaper than continuing to operate existing coal plants. By adding more solar energy to their systems, utilities can help make sure that the consumer costs of energy remain stable, since they are not affected by fluctuating fuel prices.
Solar power also has the benefit of producing electricity during the times of day when demand and power costs are the highest. On a midsummer afternoon, for example, when homes and businesses are running their air conditioners at full power, a solar facility is generating at full power as well, which helps close the gap between electricity supply and electricity demand. This can have the effect of lowering electricity costs across the board.
Source: National Renewable Energy Laboratory. "Documenting a Decade of Cost Declines for PV Systems"