Resource

Solar Sizer

Solar system sizing tool

This simple, free program helps you understand what system you need as well its approximate cost.

The basic user interface is a house graphic. You select components from a "catalog" and drag them into the house. Detailed performance and price information is provided for each catalog item. Once the item is in the house you can change its characteristics without affecting the catalog. This allows you to quickly get a rough estimate, but fine tune it later with the exact specifications of your equipment. The program adds up the electrical requirements of your appliances and helps you select the proper components, such as PV modules, the inverter, controller and batteries. You see a warning if you make a selection that's outside the system's parameters or incompatible with other components. The program includes solar radiation data for 240 sites in North America and 50 around the world. You can also enter your own data.