The Department of Energy’s Lawrence Berkeley National Laboratory released a report September 15 finding that the installed cost of solar photovoltaic power systems in the US fell substantially in 2010 and the first half of 2011. 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, the average installed cost of residential and commercial PV systems fell by 17 percent from 2009 and an additional 11 percent within the first six months of 2011, reflecting a drop in the cost of PV modules, installation labor, marketing, overhead, inverters, and the balance of systems.