SUNNYVALE, Calif. - Feb 20 - Associated Press

In an environmental dispute seemingly scripted for eco-friendly California, a man asked prosecutors to file charges against his neighbors because their towering redwoods blocked sunlight to his backyard solar panels.

But the couple next door insisted they should not have to chop down the trees to accommodate Mark Vargas' energy demands because they planted the redwoods before he installed the solar panels in 2001.

Experts say such clashes could become more common as California promotes renewable energy and solar systems become more popular.

"Five or ten years ago, you wouldn't have seen this case because there weren't that many systems around," said Frank Schiavo, a retired environmental-studies professor at San Jose State University. "I can almost guarantee there are going to be more conflicts."

After more than six years of legal wrangling, a judge recently ordered Richard Treanor and his wife, Carolyn Bissett, to cut down two of their eight redwoods, citing an obscure state law that protects a homeowner's right to sunlight.

The couple does not plan to appeal the ruling because they can no longer afford the legal expenses, but they plan to lobby state lawmakers to change or scrap the law.

The Solar Shade Control Act means that homeowners can "suddenly become a criminal the day a tree grows big enough to shade a solar panel," Treanor said.

The case marks the first time a homeowner has been convicted of violating the law, which was enacted three decades ago, when few homeowners had solar systems.

The law requires homeowners to keep their trees or shrubs from shading more than 10 percent of a neighbor's solar panels between 10 a.m. and 2 p.m., when the sun is strongest. Existing trees that cast shadows when the panels are installed are exempt, but new growth is subject to the law.

Residents can be fined up to $1,000 a day for violations, though the judge did not impose any fines against the Treanors.

Vargas says the law protects his $70,000 investment in solar power, and he believes it should be strengthened.

"I think it's unfair that a neighbor can take away this source of energy from another neighbor," he said.

Treanor, a retired engineer, said he and his wife are not against solar power, "but we think there's a rational way to implement it."

Solar power is growing rapidly in California, which is by far the nation's biggest generator of solar energy. In 2007, more than 30,000 California homes and businesses had rooftop solar panels, with the capacity to generate 400 megawatts of electricity.

That's as much as eight power plants, according to the nonprofit Environment California.

The boom is being fueled by the California Solar Initiative, which offers homeowners and businesses more than $3 billion in rebates over the next decade to install solar-electric systems.

Both sides say they want to do what's best for the environment.

Treanor and Bissett, who drive a hybrid Toyota Prius, argue that trees absorb carbon dioxide, cool the surrounding air and provide a habitat for wildlife.

Vargas, who recently bought a plug-in electric car, counters it would take two or three acres of trees to reduce carbon dioxide emissions as much as the solar panels that cover his roof and backyard trellis.

Bernadette Del Chiaro, clean energy advocate for Environment California, says the solar shade law might need to be revised to prevent similar disputes.

"We want to make sure we are protecting individuals who have invested a lot of money in solar power, which is an important resource for the state," she said. But lawmakers might want to "take a look at the policy and make sure it's written in a way that's fair to everybody."