Some homeowners go solar to lower their electric bills. Others go solar because they’d rather their home run on electricity made on their own roof than on fuel burned somewhere else.
Renewable energy for your home replaces power from natural gas plants during daylight hours and produces clean electricity for decades. Paired with a home battery, that clean power can keep working into the evening. Here in New Hampshire, every rooftop system adds to the state’s clean energy share.
This post covers how rooftop solar affects the grid, how quickly solar panels offset their manufacturing energy, and what selling your renewable energy certificates (RECs) means for your green claim.
When Rooftop Solar Has the Biggest Impact on New England’s Grid
New Hampshire is part of a regional grid run by ISO New England, the organization that balances electricity supply and demand across the 6 New England states. At any given moment, your solar panels effectively replace power from the plants currently meeting demand, and natural gas plants typically fill that role.
On the hottest summer days, demand climbs high enough that the grid turns to peaking units, which run less often and typically have higher emission rates.
However, one detail complicates this picture. The region now has more than 8,000 megawatts (MW) of rooftop and other behind-the-meter solar, and that solar has pushed the summer demand peak later, to around 5 or 6 p.m., when solar production is dropping, according to ISO New England. A MW is 1,000 kilowatts (kW). In winter, demand typically peaks after sunset, when solar panels aren’t producing at all.
This means home solar does its most direct work during the day, and pairing it with a home battery storage system lets you use that clean power in the evening, when the grid often relies on dirtier sources.
How Long Solar Panels Take to Offset Their Manufacturing Energy
Making solar panels takes energy and materials. The time it takes a solar panel to produce as much energy as went into making it is called energy payback time.
The Fraunhofer Institute for Solar Energy Systems (ISE), a German research institute, estimates in its 2026 Photovoltaics Report that today’s silicon solar panels pay back their manufacturing energy in about 1 year, depending on location.
Given New Hampshire’s climate, this means a home solar system typically offsets its manufacturing energy within its first couple of years, then produces 100% clean electricity for the rest of its 25-year-plus life.
Residential Solar in New Hampshire by the Numbers
New Hampshire has about 380 megawatts direct current (MWdc) of solar installed across roughly 25,700 installations, enough to power more than 56,000 homes, according to the Solar Energy Industries Association (SEIA). Solar provides about 2.3% of the state’s electricity, and New Hampshire ranks 44th nationally for installed solar capacity.
Those numbers leave room to grow. Each New Hampshire home that adds residential solar still makes a measurable difference in the state’s overall clean energy share.
The Environmental Downsides of Solar Panels Aren’t Bad
No energy source is free of trade-offs, and solar is no exception.
Manufacturing
Producing solar panels uses energy, water, and mined materials, including silicon, aluminum, copper, and silver. The energy payback figures above cover the energy used, while water use and mining have their own environmental costs.
End-of-Life Recycling
Solar panel recycling in the U.S. exists and is growing, but it’s still developing. Current recycling processes typically recover glass, aluminum, and copper. Our post on the lifecycle of a solar panel covers what happens at end of life.
Land Use for Ground-Mounted Systems
Rooftop systems use space that’s already built on. Ground-mounted systems use land, so thoughtful placement matters.
Are Solar Panels Toxic?
Some solar panels contain small amounts of metals such as lead or cadmium in their solder or semiconductor layers. Those materials are sealed inside the panel while it operates. The concern is disposal, so contact your state or local recycling agency when panels reach end of life. Our solar mythbuster post goes into more detail.
These tradeoffs are real. Compared with decades of electricity from fuel that’s burned, mined, and transported every day, their negative impact is very limited.
Renewable Energy Certificates and Your Green Claim
This is the part of home solar that’s rarely explained.
For every 1,000 kilowatt-hours (kWh) your system produces, it generates 1 renewable energy certificate (REC). A kWh is the energy it takes to run 1,000 watts for 1 hour. A 10 kW system typically produces about 12 RECs a year. Utilities and electricity suppliers buy RECs to meet New Hampshire’s renewable energy requirements.
A REC represents the environmental benefit of your solar power. If you sell your RECs, the buyer gets to count that clean energy toward its own renewable requirements, and you give up the right to claim it.
If your main reason for going solar is environmental, keeping your RECs is usually the right choice. By not selling them, you don’t cover up a power plant’s carbon footprint.
Find Out What Renewable Energy for Your Home Could Look Like
If you’re curious what solar could do for your home and the grid, we’re happy to help. Granite State Solar has been installing solar across New Hampshire since 2008, and our own in-house crews handle every installation, backed by a 12-year workmanship guarantee.
We start with a free, no-pressure site visit, the first step in our solar installation process. We’ll review your roof and shading, estimate how much clean electricity your home could produce each year, and answer your questions about RECs, batteries, and pairing solar with other upgrades. There’s no obligation, and you’re welcome to take the information and decide on your own time.
Sources
- WWLP, reporting ISO New England. ISO ready for summer electricity demand and early evening peaks. Accessed September 2026. https://www.wwlp.com/weather/weather-news/iso-ready-for-summer-electricity-demand-early-evening-peaks/
- Fraunhofer Institute for Solar Energy Systems ISE. “Photovoltaics Report.” Updated July 2026. https://www.ise.fraunhofer.de/en/publications/studies/photovoltaics-report
- Solar Energy Industries Association. “New Hampshire Solar” state profile. Updated September 2026. https://seia.org/state-solar-policy/new-hampshire-solar/
- Eversource. “New Hampshire Renewable Energy Certificates.” Accessed September 2026. https://www.eversource.com/residential/about/doing-business-with-us/interconnections/new-hampshire/renewable-energy-certificates
