Ever since 2015, EIA’s monthly estimates of electricity generated from residential small-scale solar photovoltaic (PV) systems less than 1 megawatt in capacity have set new monthly high records. The latest reported month is no exception. The June 2017 estimate for small-scale solar PV output hit a monthly record high of 1,460 gigawatthours (GWh). This value represents a year-over-year increase of 34.4% compared with the June 2016 level, according to preliminary 2016 and 2017 EIA data.
The growth in residential solar PV generation has coincided with the continued expansion of residential solar PV capacity, which increased by almost 35% from June 2016 (6.35 GW) to June 2017 (8.57 GW) and more than triple the 2014 value (2.68 GW). Driving this growth are several factors including decreases in the price of solar PV technologies; state policies that encourage solar investment (e.g., net metering renewable portfolio standards, etc.); the emergence of third-party operators (e.g., Solar City) that facilitate net metering arrangements between themselves,
end-use customers, and utilities; and federal incentives.
Most residential small-scale solar PV systems are relatively small, averaging about 5 kilowatts (kW). They are usually installed on the rooftop of the residence and provide electricity directly to users. In cases when PV generation exceeds residential use, the surplus electricity will flow into the connected utility distribution system, where the residential customer in some cases gets a monetary credit depending on a state’s net metering rules.
In June 2017, 10 states accounted for 85% of U.S. residential small-scale solar PV electricity generation, according to estimated residential small-scale PV generation data released in EIA’s August 2017 Electric Power Monthly report. The top three states included California (684 GWh), Arizona (121 GWh), and New York (82 GWh). The top 10 states are divided into two groups, one clustered in the southwest, plus Hawaii, where high solar irradiance is conducive to solar PV generation.