A solar photovoltaic water heater mainly comprises at least one solar photovoltaic generation plate, a water storage tank, a controller and a temperature limiter, wherein the solar photovoltaic generation plates are in series, in parallel or in serial-parallel connection to form a solar power supply and connected with a low voltage electric heating tube installed in an indoor water storage tank through a lead of the solar power supply, a solar photovoltaic plate A is formed by single crystal silicon or polycrystalline silicon cell sheets which are connected in series or in parallel, toughened glass is attached to front sides of the solar photovoltaic generation plates, back plates are positioned at the backs of the solar photovoltaic generation plates, the solar photovoltaic generation plates are integrally fixed by a framework at the periphery, and positive electrode output lines and negative electrode output lines are arranged on the back plates. The solar photovoltaic water heater can totally utilize energy of the photovoltaic electricity to generate heat, outlet hot water has the same pressure as tap water, temperature is identical, thermal insulation of the hot water is good, electric supply can be appropriately used for heating in rainy and snowy days, energy consumption is small, full automatic control is achieved, the structure is reasonable, application is wide, and the solar photovoltaic water heater is safe, reliable, environmental-friendly and energy-saving.