I'd like to power our home with solar and sell the excess back to the grid. Can you help?
Before buying a solar system, the best practice is to "reduce, then produce" as I advised in a separate Ask A Pro article here. The relatively inexpensive recommendations in a Home Performance Audit will increase the energy efficiency, comfort, and health of your home, enabling you to invest in a more modest and effective photovoltaic system.
After that, take a look at your new reduced utility bills to help decide the size of the PV system you really need. Most homes will do well to produce half to two thirds of their average electric consumption. This assumes that you have a utility grid to which you can remain connected to make up the difference. Check with your local utility company to see what programs are available. Many utility companies allow you to credit the excess electricity you produce during sunny days toward the electricity you need at night and days with insufficient sun. This is commonly known as net metering. The Database of State Incentives for Renewables and Efficiency (DSIRE) provides a list of net metering rules by state.
In general, there are more incentives for grid-tied systems than for off-grid systems, but a grid-tied system means you’ll be without electricity during a blackout or power failure. The only way to be completely independent of the utility grid is to have battery back-up, but this is expensive and hard to justify unless you live in a remote location or really must have continuous power.
For more information:
The U.S. Department of Energy also has details on its website about net metering.