Solar heat pump solution for water, pool heating


U.S. solar thermal panel manufacturer Fafco has developed a photovoltaic-thermal heat pump solution for water and pool heating.

“The solution utilizes an open-loop solar drain-back style system that is coupled to the Phoenix which would be mounted on a wall near a hot water storage tank,” the company's founder, Freeman Ford, told pv magazine. “The simplicity of the system lends itself to a quick to understand and install solar system along with an all-in-one heat pump, circulation module and additional thermal storage of approximately 5kWh.”

The Phoenix system consists of three elements: a CoolPV photovoltaic-thermal (PVT) module manufactured by Fafco; a 5 kWh thermal battery with a heat pump, two braised heat exchangers, two pumps, and multifunction software; and a 50-gallon electric hot water heater provided by unspecified manufacturers in California.

“The system consists of several well-known and proven technologies connected in a novel way with patents issued and pending,” Ford further explained. “The system uses software for several purposes including to optimize performance and load level for the utilities.”

According to Fafco, the two circulation pumps with speed control are designed for optimal efficiency. One supplies the solar loop and the other for getting the heated water to and from the hot water storage tank. These pumps interface with the refrigerant loop in the heat pump via the two brazed plate heat exchangers that have been specified, optimized, and tested for this purpose.

The system, according to the manufacturer, has several advantages compared to what is available on the market today. For example, the system is connected to 120Vac, which eliminates the requirement to rewire for 220Va, and, is said to be 50% more efficient than the air-sourced systems being sold today. “Furthermore, it is designed for retrofit in existing systems or a different version can be used in new home construction,” Ford said. “Phoenix systems will be interconnected for use by the electric utilities to shift load from peak to off-peak demand.”

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The 60-cell monocrystalline PVT panel is made with a photovoltaic module provided by U.S. manufacturer Silfab that has been retrofitted by Fafco with its own thermal collector system. It is available with PV power output ranging from 310 to 330 W and power conversion efficiencies ranging from 18.2 to 19.4%. The open-circuit voltage spans from 36.69 to 40.50 V and the short-circuit current from 10.22 to 10.42 A.

All CoolPV modules (including the thermal unit) measure 1,700 x 1,000 x 123 mm, weigh in at 26 kg, and have a roof load of 15.3 kg/m2. The power temperature coefficient is -0.36% per degree Celsius and the maximum system voltage is 1,000 V.

As for the thermal panel, which is the same for all three module wattages, it has an operating pressure of 20 pounds per square inch (psi) and an operating temperature range between 15 and 38 degrees Celsius. Its stagnation temperature is 58 degree Celsius. For a commercial pool case study, the manufacturer recommends the installation of 40 CoolPV modules with an aggregate capacity of over 12 kW.

The California-based company plans to launch the Phoenix system next year. “Initially our sales will focus on new home construction, heating, ventilation, and air conditioning (HVAC) and PV dealers,” Ford said. “We expect to be selling Phoenix by late 2022 accelerating exponentially in the years to follow.”

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