Solar calculator shows what size solar system you need, how much a solar panels cost, rebates available in your area and your payback time

This estimate will tell you:

The size of system you need;

The roof space you need;

The incentives and tax credits you get;

A ballpark cost based on industry averages;

Pricing from local installers(if available);

You will get an instant ballpark estimate, a detailed estimate by email, and be contacted by one or more local installers who will verify the details of your estimate.

http://www.solar-estimate.org/?page=solar-calculator&aff=1&cam=26