Over the past year, Capital Sun Group has been working with SunDrum Solar, Net Zero Meter, and New Grid Energy to develop a solar source heat pump system that incorporates a hybrid photovoltaic (PV)/solar thermal collector array that generates electrical power and solar thermal energy simultaneously.
Capital Sun Group (CSG) removed circa 1980 Carrier flat plate collectors and replaced them with 51 SunPower X21-345W panels that are backed with SunDrum Solar thermal panels. Also an existing photovoltaic system, which consists of 50 SunTech 185 W panels with Enphase micro-inverters, was installed by Astrum Solar about 2 1/2 years ago. CSG moved half of these panels into new positions and added SunDrum Solar thermal panels to the backs of these as well.
Capital Sun tied all the 76 SunDrum Solar collectors to the source side of a 6-ton WaterFurnace (WF) water-to-water source reversible heat pump. This permits a significant enhancement of the solar thermal collection performance. There are two 1000 gallon storage tanks in the basement, and heating and cooling is provided in six zones by six distributed water-to-air heat pumps that were all functional and left in place. The only difference is that instead of the Carrier flat plate collectors heating their source loops and 2000 gallons of storage for solar assist, the home now has the SunDrum Solar collectors and the WF heat pump providing the the solar source heat in the winter months.
In the summer months, when space cooling is needed, the six water-to-air heat pump units will function normally. In the daytime during peak utility rates, the waste heat is parked in the 2000 gallon solar storage tanks. After the rates drop at 8:00 pm, the WF heat pump comes on to reject the stored heat to either the 40,000 gallon swimming pool or up to the uninsulated unglazed SunDrum array on the roof to be re-radiated to the night sky. The 2000 gallons are cooled in this manner all night until 07:55 am or until the tanks reach 40 F so they are ready to accept the next day's peak period waste heat.
Major advantages of this system's design include:
Synergy of both solar power and heat collection from the same roof real estate more than triples the energy harvesting of PV alone.
Solar source heat pump configuration with unglazed solar collectors maximizes and optimizes solar collection and capital investment ROI.
'On Demand' solar thermal collection. 24/7 operation when ambient is greater than zero Celsius. Solar thermal collection/heat rejection is possible during inclement weather as well as night time.
Summer cooling waste heat is rejected to the swimming pool as a first priority and then to the night sky via the essentially unglazed and uninsulated SunDrum collector array.
Heat pump COPs typically range from 4 to 6 during sunny collection times and 3 to 4 during non-optimal periods.
Greater solar thermal collection equals greater solar thermal renewable energy credit payments.
By cooling the rear surface of the PV panels, power production is improved..