The latest generation of air source heat pumps and falling costs of solar electric panels have lead many homeowners and businesses to combine these technologies to heat and cool their buildings using free energy from the sun. Also known as Heat Pump Solar Space Heating, this method is growing in popularity.
Once such business is Northeast Radiant Technologies (NRT), who recently installed a 14.4kw solar electric array on the open south-facing roof of their Gardiner, Maine offices, alongside a Daikin Altherma air source heat pump.
NRT is a full service heating system design company so they knew the full range of solutions available: wood/pellet boilers, high efficiency gas, electric boiler, etc. They chose electric heat pumps because the idea of using solar panels to generate all their heating and cooling was incredibly compelling.
“The ability to go Net-Zero with a PV array for a small business like ours was really attractive,” says NRT Co-founder Rob Brown, “With our competitive [Efficiency Maine] grant, our time to pay back the system cost is less than 7 years and even with just the base tax credit it’s about 13. We felt if we could really tread that lightly on the earth for that kind of a price it was well worth it to us. And of course, in the end it’s an economic winner as well.”
NRT was able to take advantage of a suite of rebates including a $2,000 Maine state rebate (recently increased to $4,000 for businesses), a 30% Federal Investment Tax Credit, Accelerated Depreciation Benefits, and an Efficiency Maine grant.
Unlike a choice to invest in fossil fuels, NRT knows that in the future their cost of energy will never increase. The solar electric system, installed by local solar pros ReVision Energy, will produce a little over 18,000 kWh of power a year – a savings of close to $3,000 annually at today’s prices.
The solar electric panels are long-lived, with an expected life span of 30+ years, and contain no moving parts. Whenever the sun is out, clean electricity is generated and either used immediately in NRT’s offices, or exported to the grid.
Unlike traditional resistive electric heat, the Daikin Altherma heat pump moves air rather than heating it directly. This process makes it 2-3 times more efficient than resistive electric heat (this is called a COP of 2-3). The system can extract heat from ambient air as low as -4°F!
This combination of efficiency and renewable energy generation makes for a perfect situation for NRT: “We love watching the array generate juice,” Brown says, “It’s made limiting our power usage here to reach the net zero goal a fun game we all like to play. We really feel like we’re making a difference.”