New Home Harnesses PV to Power Geothermal System

December 22nd, 2011 by Fred Greenhalgh
Solar Powered Geothermal System - Kennebunkport Maine Solar

This home in Kennebunkport, ME is almost 100% solar powered, using solar generation to power a geothermal heat pump system.

George Longstreth’s dreams of a solar home started nearly a decade ago, when he had a crude off-grid system installed for a seasonal beach cottage on Baker’s Island, MA. “It was basic, just four small panels, but it was enough to run the microwave for a few minutes or brew a pot of coffee. It got me thinking about how this technology could be applied for a normal home.”

This thinking process lead him to Yestermorrow Design/Build School in Warren, Vermont, where he learned the basics of green building and passive solar design. Then, he scoured Northern New England for an ideal location to build his solar home, a search that took him from Southeast New Hampshire to Portland, Maine, before he found the property of his dreams in Kennebunkport.

“It was a beautiful property with good access to solar south,” he says, “That’s when I started assembling the best team of local contractors to make the project happen.”

His search for a solar contractor brought him in contact with a number of companies in Southern Maine, but he chose ReVision Energy because “you knew what you were doing.” After a preliminary meeting with engineer Geoff Sparrow, ReVision worked with George and his architect, Hans Warner, to design a 8.28kw solar electric system to be mounted on the home’s south-facing roof along with 2 flat plate solar hot water collectors for his domestic hot water supply.

Solar PV + Geothermal = Synergy

Solar is just one part of the renewable energy systems in Longstreth’s new home. George also contacted Dr. John Logan of Water Energy Distributors for advice on installing a geothermal system. Dr. Logan connected George with New Energy Solutions of Standish who designed and installed a geothermal system consisting of two heat pumps, one for 1st floor radiant heat, and another for cooling and 2nd floor heating.

“It was great when I got all these smart people in the room together to talk about the synergy between renewable energy systems,” George says, “Our predictions are that the solar will provide around 50% of the electricity used for geothermal heating during the heating months, and 100% of my household ‘plug’ loads the rest of the year.”

Designing a home that is mostly renewable-powered requires being very conscious about energy use, and Longstreth’s home takes this concept to heart. His home is heavily insulated, consisting of a double-framed 2×6 + 2×4 wall system filled with compacted cellulose insulation, for a R40 rating in the walls and R60 in the ceiling. His home takes advantage of its south-facing orientation to incorporate passive solar features, such as windows installed for optimum solar gain and a special 1 1/2″ slab to collect passive heat.

Investing in Solar

As his project nears completion, George looks forward to a life of minimal energy bills. “The new home uses no oil whatsoever, very little electricity and very little propane. We bucked the attitude of ‘fly now, pay later’ to ‘pay now, fly later.’ The tight-fisted Yankee in me can’t let this bountiful renewable energy go to waste while we purchase oil from our enemies overseas.”

George estimates that his mechanical systems made up about 25% of his overall project budget, and that with state and federal incentives, his renewable systems were cost-competitive with installing a traditional heating system. “It’s a no brainer, and we’re already seeing results. After our first month, our electric bill went from around $80 to -$10! We can’t wait to see how it performs long term.”


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One Response to “New Home Harnesses PV to Power Geothermal System”

  1. HK Chaudhary Says:

    Thanks for this inspirational writeup. George Longstreth’s dreams of a solar home came true. But not everyone is that lucky! Producing your own electricity by harnessing the energy of the sun is the most ‘cost-efficient’ alternative for homeowners. Not only installing solar panels at home would help you to reduce your energy consumption, but also you’ll be contributing towards reducing greenhouse gas emissions.