The Pew Research Center found last month that 89 percent of United States adults want to expand solar power, the highest of any electricity source surveyed.

{mosads}“Solar’s not a tough thing to sell. People want more solar; they want more solar business in their state,” Hennessey said in an interview in his downtown Washington office, where he leads a team that includes three other lobbyists, along with about 20 employees who work in other segments of the San Mateo, Calif.-based company.

“It’s like puppies and kittens,” he said.

In fact, expanding solar power has a higher approval rating than kittens, apple pie and laws against child labor, according to YouGov.

Nonetheless, Hennessey has his work cut out for him in protecting federal policies that help rooftop solar power, the industry that SolarCity, which is voting this week on a proposed merger with Tesla Motors, helped grow dramatically with creative financing for homeowners.

His work lately has mostly revolved around protecting the investment tax credit (ITC) that provides incentives to build solar power capacity and beating back proposals that could hurt the market for rooftop solar via amendments to the federal law that dictates how states regulate electricity.

“I think we’ve hit the point in 2016 when no one cannot like solar. They can claim it’s too expensive, but that just means they’re reading something from 10 years ago,” Hennessey said.

“If you’re opposing it, it’s because you’re not making money off it.”

Next month marks 10 years that Hennessey has been lobbying for solar power, with the first five spent at the Solar Energy Industries Association (SEIA), the main lobbying group for the industry.

He is fluent in electricity policy, both at the federal and state levels. He also knows that, as a corporate lobbyist, his best weapon can be the economic and employment benefits that SolarCity brings to a specific state or congressional district, such as the warehouses it uses near major cities, employing up to 100 people in each.

“We’re in 20 states. We’re in about 90 congressional districts,” he said. “People are very excited about those kinds of jobs.”

Hennessey went to Oberlin College and Boston College Law School and practiced law in his native Massachusetts before going into federal policy.

“I failed to get to the Hill, but I ended up lucking out and getting into a phenomenal consulting company called the Brattle Group,” he said.

Brattle led him to the SEIA. He was the group’s fourth employee, but it grew rapidly alongside the solar industry, due largely to the creation of the solar ITC in the Energy Policy Act of 2005.

Solar now accounts for one out of every 83 newly created jobs, according to the Solar Foundation. But it’s still a small electricity source, making up about 0.6 percent of the country’s electricity generation in 2015.

Hennessey moved in 2012 to SolarCity, which is now the largest rooftop solar company in the country.

The wide reach of SolarCity, and rooftop solar in general, means that a lot of lawmakers have the company’s customers as constituents, and potentially the company as an ally, Hennessey said.

“People don’t want to just pass legislation and hear you go dark completely. They don’t just want to hear when you want things. They want to hear about your footprint and positive impacts to their district on regular basis,” he said.

Keeping lawmakers abreast of the company’s economic impacts is one of the top priorities for Hennessey, as is often the case with corporate lobbyists.

Now he can add manufacturing to his pitch, a bipartisan priority. SolarCity is moving into a solar panel manufacturing plant in Buffalo, N.Y., a fact that Hennessey and lawmakers such as Sen. Charles Schumer (D-N.Y.), likely the next Senate minority leader,  boast about often.

“We’re doing something pretty special in bringing a Chinese company’s technology back to the U.S., manufacturing in one of the great landmarks of manufacturing of the U.S. in Buffalo, with pretty big plans,” he said. “It’s the largest solar panel plant in the Western Hemisphere.”

Once the facility is working at full power, SolarCity plans to source most of its solar panel supply from there.

Meanwhile, on Thursday, the shareholders of SolarCity and Tesla Motors Inc. will take the final vote on merging the two companies.

Both SolarCity and the electric carmaker have eccentric South African mogul Elon Musk as chairman, and SolarCity has already started selling Tesla’s Powerwall high-capacity home battery.

Tesla has its own lobbying shop in Washington. But if the merger goes through, Hennessey would get to add battery storage technologies such as Powerwall and the utility-scale Powerpack to his lobbying portfolio, something that greatly excites the energy policy nerd in him.

“The battery storage will be a game-changer,” he said. “You’ve already heard utilities, not always the most progressive ones, saying they’re not going to invest in peaker units anymore because it’s not going to make sense when you have batteries coming down in price so quickly.”

The ITC has largely defined Hennessey’s 10 years of solar lobbying. It’s been renewed multiple times, most recently last December.

In that end-of-year package, which included an omnibus appropriations bill and extensions of numerous tax policies, solar’s ITC and the production tax credit for wind power both got five years of extension, while lawmakers also voted to lift the ban on oil exports, a big win for the oil industry.

It was the kind of grand bargain that Washington insiders often seek but rarely find. The renewable credits helped get Democrats on board, while the oil exports helped bring in Republicans.

Hennessey was a crucial player in reaching that deal, but he gives substantial credit for it to the American Petroleum Institute, an unlikely ally. Since wind and solar do not compete directly against oil, neither side objected too vociferously.

“If you’re going to bring together some very climate-conscious members and get them to like something that looks a heck of a lot like Keystone XL, it’s good to have something really sizable on the other side,” Hennessey said, referring to Democrats who opposed oil exports on climate change grounds.

Alex McDonough, a staffer working on energy policy for retiring Senate Minority Leader Harry Reid (D-Nev.), said Hennessey was a tireless and useful advocate in negotiations on the renewable energy and oil deal.

“Scott and the solar coalition did a good job of resetting their strategy and broadening their support, and it strengthened our hand when Sen. Reid was negotiating with Sen. McConnell to extend the ITC in the omnibus,” McDonough said.

Christopher Mansour, the head lobbyist at the SEIA, said it’s extremely valuable to have Hennessey at the table for advocacy.

“SolarCity’s one of the few solar companies that has a Washington presence,” Mansour said. “So it’s really helpful to us as an industry trade association to have that kind of company support here in Washington.”

Hennessey is a proud SolarCity customer himself, with 6.7 kilowatts of capacity on his Bethesda, Md., home, which he shares with his wife and two children.

“Which is more than the White House,” he points out, admitting that Secret Service staffers need ample room on the White House roof to move about.

The solar system gives him a great talking point on Capitol Hill, where he can show staffers on his phone how much power his home is producing at any given time.