Air Source Heat Pumps (ASHPs) like the one in this customer’s home are an efficient (and environmentally friendly) way to heat and cool your home.

Since the early 2000s, our clients have asked us how to use solar to heat their homes. For years, that solution involved literally trapping the sun’s heat using solar thermal collectors and transferring it to water, which could then circulate using a radiant loop. No more!

Today, efficient air source heat pumps are the system of choice for both new construction and existing homes to heat and cool, with or without solar.

An air source heat pump uses the same technology as a geothermal heat pump, but since it uses ambient air as its source (hence ‘air source’) it is a much simpler project, and as a result, a smaller upfront investment. Heat pumps used to mainly be seen in the Mid-Atlantic or Southern States, but thanks to dramatic improvements in their low-temperature performance, they are being rapidly adopted in the Northeast. The latest generation of heat pumps can provide heating to temps as low as -17 Fahrenheit.

The vast majority of the systems we install are ductless, consisting of an outside compressor/evaporator and an inside air handler. The units are connected using copper refrigerant line and we triple evacuate the lines with a deep vacuum and dry nitrogen purge, before charging them with an advanced refrigerant for the most efficient and reliable installation.

Based on current grid electricity prices, it costs the equivalent of around $1.5/gallon of oil to heat with a heat pump, and using solar, as little as $1/gallon!

In cooling mode, a modern heat pump is roughly 1/2 the operating cost of a window unit air conditioner.

New England Heating Fuel Cost Comparison

The chart below compares average heating costs for different heating sources. Using recent average fuel prices in ME, MA, and NH, we can compare these fuel source by calculating their cost per million BTU (a unit of heat). You can see that it’s a lot more cost-effective for heat pumps to generate the same amount of heat as propane or oil heater, especially when powered by solar.

Fuel Source Cost per Unit Cost per Million BTUs*
Heat Pump Powered by Solar $0.08 / kWh $9.40
Heat Pump Powered by Grid $0.21 / kWh $24.60
Propane (2022 NE average) $3.89 / gallon $53.30
Heating Oil (2022 NE average) $4.95 / gallon $54.90


*Assumes typical oil boiler operating at 65% efficiency, propane at 80% efficiency, and heat pump at 250% efficiency (COP of 2.5). Solar PV kilowatt-hour cost of 8 cents per kilowatt-hour over 25-year timeframe based on typical pricing economics of a 8.5kw + system. Economics are estimates and subject to the local cost of oil, propane, and electricity.

Learn more about heat pumps on our dedicated page: Solar-Powered Heat Pumps

Water Heating with Solar

Water heating may not be the ‘sexiest’ application of solar technology, but it is one of the most cost-effective and powerful. For a home heating domestic hot water with an oil-fired boiler, you can save more than 300 gallons of oil per year for an average family of four by switching to solar hot water!

Like with heat pumps, the preferred way to get solar hot water in 2017 is to install a solar electric system, and then generate electricity which can be used to power an electric water heater. However, instead of any big-box store water heater, we strongly recommend a well-made Heat Pump Water Heater (HPWH) which offers an incredible combination of efficiency and convenience.

Some facts about Heat Pump Water Heaters

  • Instead of MAKING heat, they simply move it from one place to another, making them much more efficient than conventional electric water heaters, or other ways to make hot water.
  • While they make heat, they also help dehumidify the room they are in.
  • Highly insulated, meaning the energy you do use for hot water is not wasted in ‘standby losses’ as the tank sits idle.
  • Available in large tank sizes, which means that you can easily meet the needs of a 4+ person household with a heat pump water heater.
  • Many states have cash rebates for installing them.
  • One of the only water heating systems that can be solar powered!

Solar + Heat = Economic Powerhouse

We spoke earlier about the great economic opportunity of going solar. Well, when you combine the good economics of solar electricity, with added benefits by reducing fossil fuel use, the effect is even more powerful! Combine solar electricity with efficient electric heating and cooling equipment, to be both more comfortable in your home, and more comfortable with your wallet.

The next chapter, SOLAR POWER CAN BE STORED FOR LATER USE, goes over the advances in energy storage technologies and pricing that have made battery storage a viable option for backing up your home in case the grid goes down.

To Chapter 4

To Chapter 6

Warming up to solar energy yet?

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