Homeowners and businesses who purchased a rooftop solar electric or solar hot water system in 2014 or, businesses that provided a system through a lease to a third party, can reduce their taxes by 30 percent of the total cost of their system through the Federal solar Investment Tax Credit (ITC). Solar systems financed through PACE programs like in Milwaukee, are eligible as well. Total cost includes the system, installation and related work like wiring and related roofing modifications. There is no cap. Use IRS Form #5695. For those homeowners considering a solar installation, the solar credit is available through 2016 only. The solar ITC goes down to 10 percent for businesses in 2017. Gather your invoices, add them up, and check with your installer and tax preparer for more specific assistance.