DURHAM — Rooftop solar energy systems are no longer just for the affluent.

The cost of solar panels has fallen nearly 50 percent since 2010, even as new technologies have boosted their electrical output. The price of other solar components has also fallen sharply while achieving similar efficiency improvements. Perhaps the biggest change in solar energy systems, however, is how people pay for them. Relatively new financing options let homeowners install rooftop panels with low-interest loans and no money down.

Because solar energy can dramatically reduce or eliminate the need to purchase electricity, the monthly savings on your power bill can cover a large percentage of the loan.

Kate Epsen, executive director of the nonprofit New Hampshire Sustainable Energy Association, likened solar financing options to car loans, which became the industry norm long ago. “If solar follows a similar pathway as automobile financing, I think we will see tremendous growth in ownership and accessibility, just like we saw with automobiles,” she said.

The average home solar array costs between $15,000 and $20,000, and most people traditionally paid cash, said Heather Fournier of ReVision Energy in Exeter. These upfront costs priced most families out of solar.

Typical customers were affluent homeowners and empty nesters who wanted energy independence or sought to reduce their carbon footprint. But lower prices and new financing options combined with rising conventional electricity rates is making solar energy appealing for homeowners within the middle class, said Erik Shifflett, a partner in Granite State Solar based in Boscawan.

Solar companies are redirecting their sales pitches to this new market segment. Instead of highlighting environmental reasons, some now focus on the economic benefit.

“We do not talk about the tons of carbon offset and we do not talk about how many SUVs you've taken off the road,” Shifflett said. “Now, the only thing we talk about is how it makes financial sense.”

Granite State Solar and ReVision both have partnered with banks to provide loans as low as 2.99 percent for up to 12 years, and other companies have made similar arrangements. Monthly payments are reduced by state rebates up to $3,750 and federal tax credits up to 30 percent of the system price.

About a quarter of ReVision’s customers are financing their solar arrays, while about 80 percent of Granite State Solar customers are choosing that option.

Jack Lannamann and his wife Sheila McNamee had 21 solar panels installed on their Durham home in April using ReVision’s financing program. The system is large enough to power their entire house and is estimated to be paid off in 12 years.

The couple has long been interested in solar and hopes to reduce their carbon footprint, something Lannamann considers “a moral imperative.” They’re considering installing an electric hot water system and might even buy an electric car to tap into their solar energy production.

“This was seamless. Everything went up and we haven’t laid out a penny,” Jack Lannamann said. “It looks like we’ll be almost zeroing out our electric bill.”

Typical solar energy systems are sized to meet a home's monthly electricity demand, eliminating the need to purchase energy. This helps pay for the system but doesn't necessarily mean the end of electric utility bills. Eversource will still bill a customer charge, and N.H. Electric Co-Op members will still charge membership fees. But solar users are eligible for renewable energy credits that can help offset those fixed utility charges. Granite State Solar takes care of this step for its customers.

Also, in New Hampshire, excess electricity generated by solar panels is credited to a customer’s account against future usage, a process called "net metering." Homeowners with solar arrays that produce substantially more energy than their homes use can receive an annual cash rebate.

Homeowners wishing to take advantage of solar energy without spending a lot of money may also have the option of leasing a system. In that model, investors pay for the solar array and collect the incentives, while the homeowner receives discounted electricity. This type of program is now being offered in New Hampshire by SolarCity, a national company founded by a relative of solar pioneer Elon Musk. Shifflett said the leasing programs are popular in states where credits and incentives are worth more than they are in New Hampshire.