Build a website and application that incoporates a solar predictor tool

Currently there are lot of tools and application that tell: 1. How much sun energy is available at a particular location using GPS data and doing a lookup from the NASA open source meteorology data. The tool is Meteonorm. 2. What is the area of the roof using Google Earth. 3. Government websites that tell what is the electricity tariff for different types of customers, residential, commercial etc. So the idea is to have an online tool that allows the user to enter their address, monthly electricity bill and the tool outputs a recommended system capacity and potential savings on the bill. This is ofcourse be based on an algorithm. The website would also include some basic text and picture based content as well. While I would be providing all the necessary info it would be good if the person is resourceful in finding stuff that is needed and be proactive.