BERKELEY, Calif. — The installed cost of solar photovoltaic (PV) power systems in the United States fell substantially in 2010 and into the first half of 2011, according to a report released by the U.S. Department of Energy’s (DOE’s) Lawrence Berkeley National Laboratory (LBNL). The average installed cost of residential and commercial PV systems completed in 2010 fell by roughly 17 percent from 2009, and by an additional 11 percent within the first six months of 2011. The reductions reflect the drop in both the cost of PV modules as well as non-module costs such as installation labor, marketing, overhead, inverters, and the balance of systems. According to the report, “Tracking the Sun IV: An Historical Summary of the Installed Cost of Photovoltaics in the United States from 1998 to 2010,” average non-module costs for residential and commercial systems declined by roughly 18 percent from 2009 to 2010.

The study, which examined more than 115,000 residential, commercial, and utility-sector PV systems installed between 1998 and 2010 across 42 states, describes trends in the installed cost of PV in the United States.

The study also highlights differences in installed costs by region and by system size and installation type. Across states, for example, the average cost of PV systems installed in 2010 that were less than 10 kW ranged from $6.30/W to $8.40/W depending on the state. The report also found that residential PV systems installed on new homes had significantly lower average installed costs than did those installed as retrofits to existing homes. LBNL also noted that the average size of direct cash incentives provided through state and utility PV incentive programs has declined steadily since their peak in 2002.