Electrical off grid design...

There are two basic types of solar PV systems, off-grid and grid-tied. An off-grid system uses batteries, while batteries are optional in a grid-tied system. An off-grid system uses solar photovoltaic (PV) panels to turn sunlight into electricity, and stores that electricity in batteries for later use. Battery charging must be done in a controlled manner to protect them from damage, and for efficiency and safety. The stored energy must be converted to AC voltage in order to power ordinary household appliances.

Building a system large enough...

For most people, reducing the load by improving energy efficiency will be more cost effective than building a system big enough to handle a heavy load. Replacing incandescent lights with compact fluorescent (CFL’s), and upgrading to energy-efficient appliances are a couple of things you can do that will pay off in the long run.