A state tour of solar power installations will kick off Friday with a 10 a.m. event at Des Moines Onstage, which recently installed a 22.6-kilowatt solar power system at its building at 2124 Grand Ave. Hosted by state Sen. Rob Hogg of Cedar Rapids, the Solar Works for Iowa tour will also showcase solar installations in Iowa City, Cedar Rapids, Marshalltown, Cedar Falls, Independence, Decorah and Fairfield on Friday and Saturday.  Gov. Terry Branstad last month signed into law legislation that expands the state solar tax credit program to $4.5 million in credits annually, up from the original $1.5 million. Since 2012, the program has provided $2.8 million in tax credits, supporting more than 600 solar projects with a total investment of more than $24 million.