Solar hot water systems use solar energy to pre-heat the water that is incoming to a conventionally fueled heating tank. The warmer the water from the solar heater, the less conventional fuel will be needed to provide the household's hot water needs. During the summer months, a properly sized solar hot water system can provide almost 100% of a household's needs. Over the course of an entire year, a solar hot water system can provide up to 70% of a typical home's hot water needs.