http://www.energy.gov/taxbreaks.htm

Residential Renewable Energy Tax Credits
Consumers who install solar energy systems (including solar water heating and solar electric systems), small wind systems, geothermal heat pumps, and residential fuel cell and microturbine systems can receive a 30% tax credit for systems placed in service before December 31, 2016; the previous tax credit cap no longer applies.

That's a credit, not a deduction.