Mark Boren in Dover is an incredible solar customer. His home sports solar photovoltaic (electricity), solar hot water, and an electric heat pump powered by the solar PV. To cap it off, he added a Nissan LEAF with a solar car charger to make it the ‘quad-fecta’ – electricity, heat, hot water, and driving miles all powered… Read more
Air Source Heat Pumps
The Future of Heating has Arrived
Say “Goodbye” to oil, propane, or natural gas for heat. Lock in a cost for heating that’s less than $1/gallon oil equivalent, and dramatically reduce your home’s carbon pollution thanks to modern ductless, mini-split air source heat pumps (ASHPs).
Modern heat pumps are able to heat and cool 2-3x more efficiently than older electric technologies like baseboard and air conditioners, making them dramatically less expensive to operate than nearly every other form of heat, and the best air conditioner you can buy.
Best yet – by installing a solar electric array to power the electric consumption of the heat pumps, you are effectively heating your home with sunshine. Your solar array will generate credits in the summertime (when it is sunniest) which allow you to run the heat pumps in the wintertime (when it is coldest). Your system will effortlessly generate all the ‘fuel’ it ever needs from clean, abundant sunshine!
0-down, 2.99% financing is available through ReVision’s Own Your Power solar loan program.
Want to Heat for $1/gallon Oil Equivalent? Go Solar + Heat Pump
Most of our customers want to save money as much as they want to help out the environment. With oil prices currently low, smart consumers are investing in efficiency systems to protect themselves against an inevitable spike in rates – saving money in the short term, and saving much more money in the long-term.
|Fuel Source||Cost per Unit||Cost per Million BTUs||Cost to Heat Typical Home|
|Resistive Electric Powered by Grid||$0.14 / kWh||$44||$4,489|
|Heating Oil (2010 prices)||$3.70 / gallon||$41||$3,938|
|Heating Oil (2016 prices)||$2.70 / gallon||$30||$2,790|
|Propane||$2.50 / gallon||$35||$3,404|
|Natural Gas||$2.00 / therm||$26||$2,587|
|Resistive Electric Powered by Solar||$0.09 / kWh||$26||$2,418|
|Heat Pump Powered by Grid||$0.14 / kWh||$18||$1,706|
|Heat Pump Powered by Solar||$0.09 / kWh||$11||$1,023|
Based on fuel data and pricing from: Maine Energy Office. Assumes typical oil boiler operating at 65% efficiency, propane and natural gas at 85% efficiency, resistive electric at 95% efficiency and heat pump at 250% efficiency (COP of 2.5). Solar PV kilowatt-hour cost of 9 cents per kilowatt-hour over 25-year time frame based on typical pricing economics of a 4kw + system. Economics are roughly the same in New Hampshire or Massachusetts, subject to the local cost of oil, propane, and electricity.
How Mini Split Heat Pumps Work
Video on how mini split heat pumps work.
Air source heat pumps extract heat from the outside air using a reverse refrigeration cycle (imagine if you took a window air conditioner and flipped it around). By extracting heat from the the outside air and moving it inside, rather than directly heating the indoor air, the heat pump runs 2-3 times more efficiently than an electric baseboard heater. This is commonly referred to as a coefficient of performance (COP) of 2-3.
There are a number of different system designs, but the most common installation is a 1:1 ductless ‘mini split’ unit. This system design consists of an outdoor unit with heat exchanger and compressor, which does the actual heat extraction, and an indoor blower unit which blows warm (or cool) air directly into the home. Mini split means there is a 1:1 ratio – is one indoor unit for every outdoor unit. We also install ‘multi splits,’ (one outdoor unit to two or more interior units) and ducted units when appropriate to site specifics.
Heat Pumps are Great for Supplemental Heat for New and Existing Homes
Heat pumps are an excellent way to dramatically reduce the use of an oil or propane boiler in an existing home, without the need to fully replace the existing heating system. Heat pumps are used as supplemental heat, similar to the way wood or pellet stoves are – place it in a common area of your home and raise that area to a comfortable temperature. This allows you to lower your thermostat substantially, and rely on the efficient electric heat for most of your heating. The heat pumps will run very efficiently to temperatures as low as -15°F.
The simplicity and reliability of heat pumps also makes them a great choice for new homes, where the savings garnered by installing heat pumps instead of a traditional heating system can be used to install solar electricity for the home. By heating and cooling with electricity, and then using solar panels to generate electricity, you end up with a fully ‘net zero’ home!
We’re a Mitsubishi Electric Diamond Contractor
ReVision Energy carries the prestigious Diamond Contractor status with Mitsubishi Electric, meaning we can offer an industry-leading 12 year parts and compressor warranty on single-family, residential installation, and a 5 year parts and 7 year compressor warranty on multi-family and commercial installations.
ReVision is committed to technical excellent and our exacting engineering team feels that Mitsubishi Electric offers the best heat pump technology on the market. Specifically, we are impressed with their Hyper Heat low temperature performance and recent efficiency advancements in multi-split configurations.
State incentives are periodically offered for heat pumps, currently:
- Maine: $500 Efficiency Maine rebate per household (www.efficiencymaine.com/heat-pumps/)
- New Hampshire: $500 per 12k BTU outdoor unit (NHSaves)
- Massachusetts: We can offer incredibly good financing through Mass Solar Loan program
Adding Solar = Ultimate Flexibility and Savings
A grid-tied solar electric array is an ideal partner for an air source heat pump. Net-metering agreements mean that your solar electric array can generate electricity whenever the solar resource is available. This means that your system will probably produce more electricity than you consume in the summertime, earning you a credit.
In the wintertime, when you need the electricity to heat your home with the heat pumps, you will run from power off the grid, but instead of being billed for it, you will benefit from the credits you earned while overproducing in the summer.
The overall result: solar banked in the summer used to heat your home in the winter! No other heating system allows you to generate your own fuel automatically.
What About Ground-Source Heat Pumps? (Geothermal)
Ground-source heat pumps (AKA geothermal) are also perfect partners with solar electric arrays – as ultimately, geothermal systems are a form of electric heat just like air source heat pumps. While they do run more efficiently (COP 4-5), the upfront costs of geothermal systems ($30,000 range) can make them cost-prohibitive. We can often quote multiple air source heat pumps AND solar for around the same project budget as a geothermal system.
Why use grid-tied solar for heating?
- Affordability – Solar electric systems are more affordable than ever before, with great incentives andhistoric low pricing on photovoltaic panels. By choosing solar electric, you pre buy your fuel for the next 30-50yrs and insure yourself against future energy price increases.
- Reliability – Whether you choose to power a ground-source (geothermal) or air source (mini split) heat pump with solar panels, you will have a long-lived energy solution. Solar electric panels are maintenance-free, warrantied for 25 years, and are expected to last 30+ years. We back all of our systems with 24/7 emergency service.
- Convenience – Your PV system will be generating electric credits all summer long which can be used to heat your home in the winter. One ReVision employee put it this way – you can split and stack wood, OR you can go to the beach and let the sun do the work for you!
Space Heating with Solar Thermal
In the mid-2000s (when PV prices were roughly double what they are today) the more popular way to provide solar heat for a home was to integrate one of our solar hot water systems with traditional (boiler-fired) heating system. Doing so is a technical achievement that only a few companies are able to do, as advanced controls and design are required for a successful installation.
We have roughly 50 systems of this style operating in the field, and while they work great, the Achilles heel with this method is that, by definition, heating is needed in wintertime when the solar resource is at its weakest. On the days where heating is most needed, there is simply less (or no) sunshine available to harvest. The corollary is that in the summertime, these systems will produce a huge abundance of hot water, which many homes will not have a productive use for. The mis-match of energy need (winter) and energy availability (summer) result in an inherent inefficiency. Where these systems are great are in the ‘shoulder’ seasons of spring/fall when there is a need for heat and a reasonable amount of sun available.
Company co-founder and engineer Fortunat Mueller wrote about our design process for Mother Earth News in 2011 and that article features much more in-depth information and practical advice that holds true today.
Another note is that this type of solar space heating requires low temperature distributed (e.g. radiant floor) heating, and are not compatible with most high temperature (baseboard) heating systems. If you are looking for a true boiler replacement, consider a fully automated pellet boiler.
Due to these limitations, combined with the rapid decrease in cost of solar photovoltaic technology and the improvements in latest generations of heat pumps, electric + PV heating has almost completely replaced solar thermal + hydronic distribution for a solar powered heating system.