The seekers and free-range thinkers who frequented the store, in Willits, California, quickly snapped up the three sample panels. Then the 10 Schaeffer bought after that. And the 100 he bought after that. And the 1,000 after that. The entree made the young entrepreneur one of the first people in America to sell solar technology to the public, said Spies, the solar historian.

“What John was doing back in the 1970s and 1980s was really monumental for people living off the grid out here,” said Chiah Rodriques, a second-generation marijuana farmer on the Greenfield Ranch commune west of Ukiah. “It sparked a lot of conversation, a lot of ideas, and really changed people’s lives.”

Rodriques is now farming cannabis legally with her husband, Jamie, and continuing to live off the grid on Greenfield Ranch, a complex of homes and hand-built retreats strung together along dirt roads with names like Radical Ridge. Her family lives with a solar array that Schaeffer initially supplied. In the early days, power remained so low that running something like a blender would dim the lights. But Rodriques’ 4,500-watt system now provides enough juice for a dishwasher, her kids’ video games, a television and more. (Today’s solar panels produce at least twice the wattage per square foot as their 1970s forerunners.)

“I'm proud of our lifestyle,” said Rodriques, 38, the mother of a 17- and a 10-year-old. “And I think it's great that people are coming to understand it's the way to be.”

Beatty checks the charge levels of batteries that store energy produced by solar panels. Elijah Nouvelage / for NBC News

Rodriques said motivations for going solar have come full cycle — from the idealism of the Back to the Land movement in the ’70s, to the pragmatism of the early pot growers, to a new generation that again emphasizes the environmental benefits of going green. If the children of cannabis grew up with one ethic, it’s that life’s highest purpose is not kowtowing to Washington, or any other central authority.

“The question is, ‘How do we live more sustainably within this model?’” she said. “It’s just good karma.”

‘EVERYONE CAN MAKE A DIFFERENCE’

A study a year ago by Sweden’s Lund University assessed a range of ways people can change their behavior to lower their carbon footprint, since excess carbon dioxide emissions produce a warmer atmosphere, which, in turn, lays the groundwork for more floods and droughts and a cascading set of other challenges. The most effective changes — having fewer children or cutting back on air travel — require sacrifices some might consider too great.

But in California, which leads the nation by getting more than 15 percent of its power from the sun, low-carbon acolytes have found measures big and small that can make a difference: washing clothes in cold water and air-drying them; driving hybrid or electric vehicles, or using public transportation or a bicycle; reducing the use of lumber to preserve oxygen-producing forests; and installing wind and solar power systems.

How can you reduce your carbon footprint? Roque Ruiz / Seth Wynes & Kimberly Nicholas, 2017, Environmental Research Letters

“Everyone can make a difference. The question is, do they really want to,” said Mathis Wackernagel, chief executive of the Global Footprint Network, an international nonprofit that works with people and governments to understand their impact on the Earth’s natural resources.

Wildlife biologist Quinton Martins erected 3.8 kilowatts of solar panels at his home near Santa Rosa — equipment he bought from Real Goods. “It makes no sense to be going backwards and relying on nonrenewable resources which are known to have significant ecological impacts,” Martins said. “Producing our own electricity at home and being totally off the grid feels good. For one, we don’t feel guilty about leaving a light on, or running our appliances.”

Others, like Brenda De Ramus, are starting smaller. A hospital human resources manager, she stopped at the Solar Living Center on her way from her home in Sausalito to a weekend cottage at the north end of the state. She walked out, on a recent Friday afternoon, with a solar-powered pump for a garden fountain.

De Ramus, 55, says she intends to venture further into the self-sustaining lifestyle. “The population is growing, growing, growing, and our resources aren’t keeping up,” De Ramus said. “We have got to understand how our Earth works and how our natural resources work. … So I am excited any time there are ideas put out there about alternative ways of doing things.”

Electricity-generating stationary bikes are seen on the grounds of the Solar Living Center. Elijah Nouvelage / for NBC News

Ricki Lou, a musician from Alameda in the Bay Area, came to the center looking for a solar panel for her car, to provide power on her frequent camping trips. And she brought a friend, who was inquiring about a Solar Living Center internship, which includes lessons on wheat grass cultivation and composting.

Lou, sporting a cowboy hat and patchwork gypsy dress, vowed to be back. “There is just so much knowledge here,” she said.

This may not quite be the “revolution” that Schaeffer hoped for in 1971 when he left Berkeley and visited the Rainbow commune, near the Mendocino County town of Philo. He intended to stay a weekend and instead lasted for six years, believing the world might evolve into a place that disdained pesticides, rejected all forms of discrimination and promoted social justice “everywhere.”

Now, the green power trailblazer sees the revolution as more of a painstaking evolution. Still, he’s determined to expand his mission. In the coming weeks, he plans to rename his solar center “Ecotopia.” Along with the rebranding — the center is a familiar stopping point in the town of Hopland (pop. 807) on U.S. Highway 101 — will come expanded programs and special events. The founder hopes the makeover will double the number of visitors to the center, from an estimated 250,000 to 500,000 a year.

In Schaeffer’s dream, people will flock to Ecotopia, named for a 1970s cult novel about an ecologically balanced paradise on Earth, to take courses in aquaculture (gardens floating atop fish-fertilized pools of water), learn to build structures of rice-straw bales and rammed earth, convert shipping containers into solar-powered micro-homes, and, of course, install their own solar- and wind-power generators.