Water heater having a supplemental photovoltaic heating arrangement

A water heater comprising:

• a tank defining an interior volume to contain a quantity of water;
• a primary heating arrangement comprising at least one primary heating element disposed with respect to the tank to apply heat energy to the water to heat the water, said primary heating arrangement comprising at least one primary resistive element energized by AC power, said primary heating arrangement including at least one thermostat to detect temperature of the water;
• a supplemental heating arrangement operative to supply additional heat energy to the water to lessen energy usage by said primary heating arrangement, said supplemental heating arrangement including
• at least one photovoltaic panel,
• a supplemental heating element, and
• control electronics operatively interposed between said at least one photovoltaic panel and said supplemental heating element;
• and
• a controller in electrical communication with said primary heating arrangement and said control electronics of said supplemental heating arrangement to selectively control heating at said at least one primary heating element and said supplemental heating element, wherein the controller is operative to maintain said water temperature during standby periods between upper and lower set point temperatures and to raise at least the lower set point temperature in response to a level of available energy from the at least one photovoltaic panel.

A method of controlling operation of a water heater having a primary heating arrangement that is operative to apply heat energy to water contained within the water heater to maintain temperature of the water during standby periods between a predetermined upper set point temperature and a predetermined lower set point temperature, said method comprising steps of:

• providing a solar heating arrangement operative to apply additional heat energy to the water to lessen energy usage by the primary heating arrangement, said solar heating arrangement including electronics operative to detect availability of solar energy;
• determining whether abundance of solar energy at a particular time exceeds a threshold;
• if the abundance of solar energy exceeds the threshold, raising at least the predetermined lower set point temperature;
• and
• applying heat energy from the solar heating arrangement to the water if the water temperature is between the predetermined upper set point temperature and the predetermined lower set point temperature.

A method of controlling operation of a water heater having a primary heating arrangement that is operative to apply heat energy to water contained within the water heater, said method comprising steps of:

• providing a solar heating arrangement operative to apply additional heat energy to the water to lessen energy usage by the primary heating arrangement;
• determining whether solar energy is available at a particular time;
• if the additional heat energy is available, applying the additional heat energy from the solar heating arrangement to the water;
• while the additional heat energy is being applied from the solar heating arrangement, selectively operating the primary heating arrangement to also supply heat energy to the water to maintain a temperature of the water between upper and lower set point temperatures;
• and
• wherein a controller is operative to adjust at least one of the upper and lower set point temperatures in response to changes in availability of said additional heat energy.