Potentials and Challenges of Solar-assisted Heat Pumps

October 7th, 2019

Solar-assisted heat pumps are being introduced as hybrid climate control systems. Simply put, the technology couples two energy-efficient heating technologies together to create a single, blended climate controlling system. Without the solar panels, the refrigerant-powered equipment does its best to absorb heat out of the outside air. Paired now with a solar collector unit, the refrigerant has more energy to feed upon, so it operates much more efficiently.

SAHP Technology: What’s The Downside?

Working as one integrated package or as two systems in parallel, heat captured from the sun is quickly extracted by the evaporator coil and conveyed into a property by the reverse-refrigeration effect. The fluid acts predictably, as controlled by the vaporization and condensation properties of a stated refrigerant. Check and expansion valves further regulate the process. In reviewing their potential for super-efficient heat extraction, shouldn’t every heat pump be using a solar panel? That’s a compelling argument. Only, there are a few problems standing in the way of a full-on hybrid-system heating revolution. For one thing, the sun doesn’t shine all the time. For another, and this time we’re looking at heat pump drawbacks, colder ambient temperatures can hamper how well a reverse-cycle unit extracts heat. However, that’s a drawback that only applies to air-source SAHP technology, not to the newer hybrid systems.

Hybrid Solar-Assisted Heat Pumps

Air-source systems work well in milder areas. The heat pumps absorb trace quantities of ambient heat from the outside, then the solar panels on a structure’s roof further boost this cost-effective heating tech. Problem is, the equipment won’t work in a colder climate, which is when people really need their heating most. To overcome this drawback, further process hybridization has taken place. Now, with a more integrated mix of tubes and fittings, the equipment directs the heat pump refrigerant directly into the solar panels, thus creating an even more efficient heat extraction loop. Unfortunately, even this design isn’t perfect. By combining core equipment parts, evaporator temperature boosts can become attenuated. In fact, some equipment configurations place the evaporator outside, where it then becomes vulnerable to subzero temperatures. That coil could very well ice up and bring the whole process to a halt.

On a positive note, there’s a solution. By improving the housings of photovoltaic panels, the fluids inside don’t become solid chunks of ice. The evaporator keeps on working, and the heat pump extracts energy from the solar panels. But there’s a downside to consider here, too. With extra gazing and insulation protecting the outside housing, equipment, costs can rise. It’s still early days for home-styled solar-assisted heat pumps, but the outlook is rosy. Dual system functionality is another compelling option, with a fan replacing the solar panels during the warmer summer months.

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