The amount of power produced will depend upon how large the system is. In Lagos the average residential customer purchases 6,500 kilowatt-hours (kWh) per year. There is enough sunshine falling upon on the average home to produce this and a system can be designed to offset all electrical needs.

The cost to accomplish a 100% system may be prohibitive and sometimes it makes more sense to simply reduce or 'shave' your consumption. Some utilities use tiered rates when they charge for consumption which means that the more energy you use the higher is the cost per kilo-watt-hour. The most economically feasible size is usually between 50% and 75% of your annual household needs.