Renewable Energy Assistance Act of 2007 - Amends the Internal Revenue Code to: (1) eliminate the dollar limitation on the tax credit for residential energy efficiency property expenditures and extend such credit through 2016; (2) extend through 2016 the energy tax credit for solar energy and qualified fuel cell property; (3) allow public electric utility property to qualify for the energy tax credit; (4) extend through 2015 the tax credit for nonbusiness energy property; and (5) modify energy efficient appliance tax credit amounts for appliances (e.g., dishwashers, clothes washers, refrigerators, and dehumidifiers) produced after 2007.