1. Costs for installed solar systems have continued to drop. Prices for rooftop solar fell yet again in the first half of 2014. We’ve already reported on the impressive recent-year drops in solar costs. For their latest report, GTM-SEIA calculated that, just between the first quarter of 2014 and the second, average residential solar prices dropped another 2.4 percent. LBNL found that in the first half of 2014 the larger state markets had smaller solar systems drop an average of 4 percent.