Look at Your Utility Bill to Determine How Many Watts You use.Take The Amount of Sun Your Home Receives Into consideration.The Type of Solar Panel Will Affect Its Efficiency.Remember that this calculation assumes that the panels are running under optimum conditions. More direct sunlight means your home can convert more energy into electricity. In states like Arizona and New Mexico, which are known to produce more sunlight than states in the Northeast, homeowners will likely need fewer solar panels. Nevada, Utah, Califo...See more on bobvila Department of Energy
Homeowner''s Guide to Solar | Department of Energy
For its analyses, NREL uses an average system size of 7.15 kilowatts direct-current with a 3-11 kilowatt range. According to SETO awardee