Residential and other small scale solar projects have been historically been expensive. But data from the US Energy Information Administration (EIA) and the National Renewable Energy Laboratory (NREL) shows that self-generation is now the least expensive way to generate electricity for a home or small building!
Note: These numbers are based on national averages. Actual prices for residential grid electricity vary by state; and the cost (LCOE) of residential-scale projects is heavily dependent on local factors like annual sunlight (irradiance), shading, roof angles, financing costs, and local net metering or feed-in-tariff policies. Nonetheless, even with local variations, the majority of residential solar projects are now economically attractive.
To see the original source links and calculations, click here: Is it cheaper to build residential rooftop solar or buy power from the grid?