PV & heat pump | Lincoln

rec-solar-maine-array-lincoln
LINCOLN COUPLE MOVES CLOSER TO NET ZERO USING SOLAR AND HEAT PUMPS

With low electrical loads and a strong interest in solar technology, a client in Lincoln approached Insource Renewables to determine how to most effectively utilize solar energy.

While the electricity rates from Emera Maine are relatively high (17 cents per kilowatt-hour at the time of the installation), the billing nuances can make solar a challenging value proposition for clients with electrical loads of the scale for this project. The average monthly consumption for this home is roughly 200-250 kilowatt hours.

At the time of the installation, Emera had a minimum monthly charge of $7.48 for the first 100 kilowatt-hours of electricity consumed on site. This charge is applied regardless of whether the home consumes any electricity. This means that a grid-tied solar PV system forfeits 100 kilowatt-hours – roughly $10 – of transmission and distribution benefit each month that it generates more electricity than it consumes. For an average household that uses 500-600 kilowatt-hours per month, this impact is fairly negligible. For a household that uses 200-250 kilowatt-hours of electricity monthly, this can reduce the overall benefit of the system by 25%.

One approach to increase the project viability is to offset other household fuel use with electric-based heating. In this case, we installed a mini-split heat pump to offset the owners’ oil usage. This increased the electrical demand and improved the economics of the solar while offsetting fossil fuel usage and furthering the owners’ energy independence.

As with a vast majority of the PV systems we install, the solar inverter is connected to the Internet to monitor system production and functionality. To simplify the communication between the inverter and the wireless adapter, we installed a pair of powerline adapters (see photo below) that allows for easy transmission of data through the electrical wiring in the home. This is provided for no additional charge.