The Appraisal Institute has released a study concluding that solar photovoltaic systems typically increase market value and almost always decrease marketing time of single-family homes in the Denver metropolitan area. A PV system is a solar electric system that is designed to convert sunlight into electricity. The Appraisal Institute worked with the Colorado Energy Office to analyze 30 homes in the Denver metropolitan area that had a PV system installed at the time of sale and sold and closed between Jan. 1, 2011, and May 31, 2013.