Installations of PV systems have been expanding at a rapid pace in recent years. In the United States, the market for PV is driven by national, state, and local government incentives, including upfront cash rebates, production-based incentives, requirements that electricity suppliers purchase a certain amount of solar energy, and Federal and state tax benefits. These programs are, in part, motivated by the popular appeal of solar energy and by the positive attributes of PV - e.g., modest environmental impacts, avoidance of fuel price risks, coincidence with peak electrical demand, and the location of PV at the point of use. Given the relatively high cost of PV, however, a key goal of these policies is to encourage cost reductions over time. Therefore, as policy incentives have become more significant and as PV deployment has accelerated, so too has the desire to track the installed cost of PV systems over time, by system characteristics, by system location, and by component. A new Lawrence Berkeley National Laboratory report, 'Tracking the Sun: The Installed Cost of Photovoltaics in the U.S. from 1998-2007', helps to fill this need by summarizing trends in the installed cost (i.e., the cost paid by the system owner) of grid-connected PV systems in the U.S. The report is based on an analysis of project-level cost data from nearly 37,000 residential and non-residential PV systems completed from 1998-2007 and installed on the utility-customer-side of the meter. These systems total 363 MW, equal to 76% of all grid-connected PV capacity installed in the U.S. through 2007, representing the most comprehensive data source available on the installed cost of PV in the United States. The data were obtained from administrators of PV incentive programs around the country, who typically collect installed cost data for systems receiving incentives. A total of 16 programs, spanning 12 states, ultimately provided data for the study. Reflecting the broader geographical trends in the U.S. PV market, the vast majority of the systems in the data sample are located in California (83%, by capacity) and New Jersey (12%), The remaining systems are located in Arizona, Connecticut, Illinois, Massachusetts, Maryland, Minnesota, New York, Oregon, Pennsylvania, and Wisconsin. The PV systems in the dataset range in size from 100 W to 1.3 MW, almost 90% of which are smaller than 10 kW. This article briefly summarizes some of the key findings from the Berkeley Lab study (the full report can be downloaded at http://eetd.lbl.gov/ea/emp/re-pubs.html). The article begins by summarizing trends related to the installed cost of PV systems prior to receipt of any financial incentives, and then discusses how changes in incentive levels over time and variation across states have impacted the net installed cost of PV to the customer, after receipt of incentives. Note that all cost and incentive data are presented in real 2007 dollars (2007$), and all capacity and dollars-perwatt ($/W) data are presented in terms of rated module power output under Standard Test Conditions (DC-STC).
