In 1993, Paul Lyons and his young family arrived in Oaxaca, Mexico, where the Zapotec people have thrived sustainably for 3,000 years off of little more than sun, rain, and soil. It was there, living among the Zapotecs, where he learned that wherever you call home, you have a responsibility to its land, and its people.

That’s where, for Lyons, bringing solar energy to the masses evolved from being his job to being his life’s mission.

Paul Lyons and Solar Workshop participants in Oaxaca, Mexico

Four years later, in 1997, he moved his family to Cambridge, where change-the-world conversations around alternative energy were already well underway. He was drawn there because of the city’s growing interest in solar energy — not to mention the proximity to engineering powerhouses Harvard and MIT.

Today, as solar becomes the fastest growing alternative energy in the world, with generation growing by 33 percent in 2015 alone, that Southern Mexico state Lyons called home before Cambridge has taken on even greater importance.

“The Zapotecs are defined by their place. And I realized that when your place is who you are, why would you do anything to degrade your place or to spoil it or to pollute it?” Lyons said, with the same wide smile, though whiter hair, than in the pictures from Mexico that line his office.

“Because you’re essentially polluting yourself.”

Early lessons

Paul Lyons’ father first taught him how to use solar energy around their home during the 1973 oil embargo. Noticing how solar saved both money and energy, Lyons decided to dedicate his life as a mechanical engineer getting others to realize the same.

But solar energy was expensive when Lyons was starting his career in the 1990s, costing close to $10/watt compared to $.57/watt in 2015. He had to start small to make a big difference, so he began moving from one remote corner of the world to another building low-cost solar energy systems.

After spending four years in Oaxaca, he moved to Cambridge and started Zapotec Energy as a one-man mechanical engineering practice, consulting with a variety of clients on energy management, conservation, and renewable energy production.

“What knowledge I have I’ve been given to share,” he said. “I knew one of the best things that I could do was to produce electricity without a lot of emissions. And I could do that with solar. Right here, in my pueblo.”

At first, solar projects were few and far between. It was simply too expensive for homeowners to absorb the costs and there were few federal and state incentives to entice building owners to power their properties on solar. But change would come. The Massachusetts Renewable Energy Trust Fund was created in 2003 to grant rebates for solar electric systems, and more tax incentives for business owners followed in 2008. As solar became more accessible, Zapotec grew from managing two projects a year to 10 per week.

When referrals showed no sign of slowing down, Lyons grew Zapotec by four more employees.

“Massachusetts has taken a strong stance in support of solar energy, allowing the industry to really take off,” said Aaron King, a 26-year-old design engineer, who joined Zapotec in 2015. “Having the opportunity to design solar PV systems is an invaluable experience that will help me, and similar young professionals, shape clean energy solutions that can eventually be used on a national or global scale.”

Having a larger team has allowed Lyons to work with commercial and institutional developers—and allowed him to take on the kinds of meaningful projects that inspired the start of his career.

In partnership with Just-A-Start, a community development corporation, Zapotec designed a solar electrical system for a 10-unit, four-story condominium building for first-time homebuyers. The goal was to help locals who had been renting for most of their lives transition to homeownership. Zapotec designed the building’s solar electrical system and wired it so that each of the 10 units could have their own electrical solar production, saving residents from costly electric bills.

And last year, Zapotec completed work on a large solar electric system for the rooftop of Dr. Martin Luther King, Jr. School, a new public elementary school around the corner from its Central Square office.

“And then the kids moved in,” he said, pointing to it from his office window. “It’s a beautiful school.”

Helping Cambridge see the light

It’s been nearly 20 years since Lyons moved to Cambridge, but his work isn’t close to being done. In 2015, Cambridge approved the “Getting to Net Zero Task Force,” enlisting Lyons and others to lower greenhouse gas emissions and improve energy efficiency citywide.

“My contribution is to make it technically and financially possible for businesses to leave fossil fuels in the ground,” Lyons said.

He joined with architects, city planners, energy efficiency experts, and researchers from Harvard and MIT to answer a big question: What would it take to get Cambridge to a net zero energy budget?

The task force proposed that by 2040 Cambridge could conceivably:

• Conserve 40 percent of its energy by standardizing energy efficient buildings
• Produce 20-30 percent of its energy through citywide solar electric panels and solar thermal collectors
• Purchase the remainder of renewable energy

It might take at least 50 years for Cambridge to get to 95 percent renewable energy, but Lyons isn’t discouraged.

“Does that mean I just give up today? I don’t think so,” he said. “I owe it to my children and their children someday that I did my part when I could see that the signs were clearly pointing towards the necessity of a zero carbon future.”