This paper describes a study of the national effects of widespread adoption of grid-connected residential rooftop photovoltaic (PV) systems. A Geographic Information System (GIS) model is used to estimate potential PV system adoption and PV electricity generation and the National Energy Modeling System (NEMS) is used to estimate the national effects of PV electricity generation. Adoption is assumed to occur if levelized PV system cost is less than the local average retail electricity rate at the county level. An estimate of the current "best" scenario (defined by a 6.5% real interest rate, 30-year loan life, $6 /W system cost, and $4 /month voluntary premium) results in no adoption. Several scenarios designed to stimulate PV adoption are modeled. As an example, if PV system costs are instead assumed to be $3 /W, rooftop systems are found to be cost effective in 16% of detached single- family households in the U.S. By 2015 (assuming full adoption of 4-kW systems), this results in 82.1 TWh of annual PV electricity generation, 170 TWh of avoided electricity transmission, distribution, and generation losses, 6 Mt/a of avoided carbon emissions, 50 kt/a of avoided NOx emissions, and 27.3 GW of avoided electricity generating capacity in place.

10aelectricity markets and policy group10aenergy analysis and environmental impacts department1 aMarnay, Chris1 aRichey, Cooper1 aMahler, Susan, A.1 aBretz, Sarah, E.1 aMarkel, Robert, J. uhttps://energyanalysis.lbl.gov/publications/estimating-environmental-and-economic