A solar thermal assisted water heating system includes a thermal collector comprising a plurality of fluid channels configured to collect heat from a surface of a photovoltaic module, a drain-back tank coupled to the thermal collector, a first pump coupled to the drain-back tank and configured to pump fluid from the drain-back tank to the thermal collector, a first heat exchanger configured to receive fluid from the thermal collector, a heat pump coupled to the first heat exchanger and configured to remove heat from the fluid and heat water with the removed heat, and a controller configured to control the first pump and heat pump. The system may include a photovoltaic module and a hot water tank. These systems improve the efficiency of water heating, and the drain-back tank may serve as a thermal battery that stores heat and provides the stored heat when environmental temperatures decrease.

A solar photovoltaic (PV) water heating system includes a tank including at least a first heating unit having at least first and second heating elements, at least one of which is switchable; a PV solar collector; an inverter adapted to convert the output from the PV collector to an alternating power supply; a modulator to modulate the alternating power supply from the inverter; a controller adapted to control the modulator and the switching of the or each switchable heating element; wherein the controller is adapted to control the modulator and the switchable heating elements to maximize the energy drawn from the PV collector.

A solar photovoltaic (PV) water heating system includes a tank (1.020) including at least a first heating unit (1.016) having at least first and second heating elements (1.016.1 . . . 1.016.x), at least one of which is switchable (1.014.1A . . . 1.014.1m); a PV solar collector (1.002); an inverter (1.004) adapted to convert the output from the PV collector to an alternating power supply; a modulator (1.060) to modulate the alternating power supply from the inverter; a controller (1.040) adapted to control the modulator and the switching of the or each switchable heating element; wherein the controller is adapted to control the modulator and the switchable heating elements to maximize the energy drawn from the PC collector.

The disclosed technology includes an on-demand water heater which uses an electric heat source to heat the water. The on-demand water heater can have a low fluid capacity heating chamber which has an inlet and an outlet, an electric heat source for heating the water, and a controller to control the electric heat source and maintain the temperature of the water at a predetermined temperature setting. The on-demand water heater can be powered by a direct current power source. The on-demand water heater can also utilize a solar thermal system to provide additional heat to the water.

A water heater auxiliary heating system includes a heat pump. It further includes a first tap to circulate water from a water tank to a heat exchanger within the heat pump. It further includes a second tap to circulate water back to the water tank. The heat pump is controlled by an energy management system to preferentially operate based at least in part on a status of a site energy system that the energy management system is configured to manage. The water tank stores excess energy that is generated locally at the site energy system.

A solar-powered two-bed adsorption chiller which can operate after sunset when the solar radiation intensity becomes zero. Rechargeable solar-powered batteries (SPBs) are connected to a flat-plate solar collector (FPSC). The photoelectric charges are directed from FPSC to a solar charge controller (SCC) which acts as a charge amplifier thus magnifying the total charge before it is finally collected inside the SPB for future use. The SPB is in turn connected to a resistance heating wire (RHW) which is immersed inside the HWST.

A hot water tank including: a shell enclosing a chamber containing a heat exchange liquid, the shell including a base, side wall and lid; a cold water inlet connected to a first end of a heat exchanger, and a hot water outlet connected to a second end of the heat exchanger, wherein the heat exchanger is located in an upper portion of the chamber; a primary heating element connected to a power source for heating the heat exchange liquid, the primary heating element being located in a lower portion of the chamber.

A solar photovoltaic (PV) water heating system includes a tank (1.020) including at least a first heating unit (1.016) having at least first and second heating elements (1.016.1 . . . 1.016.x), at least one of which is switchable (1.014.1A . . . 1.014.1m); a PV solar collector (1.002); an inverter (1.004) adapted to convert the output from the PV collector to an alternating power supply; a modulator (1.060) to modulate the alternating power supply from the inverter; a controller (1.040) adapted to control the modulator and the switching of the or each switchable heating element; wherein the controller is adapted to control the modulator and the switchable heating elements to maximize the energy drawn from the PC collector.

The disclosed technology includes an on-demand water heater which uses an electric heat source to heat the water. The on-demand water heater can have a low fluid capacity heating chamber which has an inlet and an outlet, an electric heat source for heating the water, and a controller to control the electric heat source and maintain the temperature of the water at a predetermined temperature setting. The on-demand water heater can be powered by a direct current power source. The on-demand water heater can also utilize a solar thermal system to provide additional heat to the water.

A heating system for heating a fluid received at an inlet, the system including a first heating device disposed in a first heated line branched from the inlet, wherein a first flow of the fluid through the first heated line is configured to be modulated by a first valve; a second heating device disposed in a second heated line branched from the inlet, wherein a second flow of the fluid through the second heated line is configured to be modulated by a second valve; and a bypass line and a third valve disposed in the bypass line, wherein a flow through the bypass line is configured to be modulated by the third valve, wherein the first and second heating devices and the first, second and third valve are configured to cooperate to heat the fluid at an outlet received from the first and second heated line and the bypass line.