Studying energy usage levels from your utility bills will also help indicate the appropriate solar panel system for your household. As a general rule, a 3-kilowatt-hour system will generate approximately 3,600 to 4,800 kwh per year; a 5-kwh system will produce 6,000 to 8,000 kwh per year; and a 10-kwh system will produce 12,000 to 16,000 kwh per year. For example, a home in Los Angeles with a roof size of 1,352 square feet that uses 1,954 KWh/month will probably need a 13.53 kwh solar power system. Before factoring in available credits/incentives, the system will cost $94,688.