What is more important, having trees or using renewable energy like solar power? It seems that if your trees block the sun from getting through to your neighbor's solar cells, you have to cut them down. But if your trees were already there and then your neighbor put in the cells, you don't have to cut them down. This is a California law which says:
"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."
You can read about this at Neighbors Clash Over Trees, Solar Power. My understanding of this case is that these Redwoods kept growing and are now casting a shadow over the solar cells that were installed after the Redwoods were there, but not as tall. This case reminds me of a blog entry I made last year called Environmentalists vs. . . . other environmentalists? Or, are birds more important than clean, cheap energy?. The idea there is that wind turbines might harm birds.
This all reminds me of The "COASE THEOREM" . It is an economic idea from the Nobel Prize winning economist Ronald Coase. It should not matter who has the property right in determining the most efficient outcome. In this case, the Redwoods owners could pay money to their neighbors so they would not have to cut them down. But the Redwood neighbors would have to care more about their trees than the neighbors care about renewable energy. If the court had ruled for the Redwood owners, and the solar neighbors cared more about their cause, they could pay the neighbors into cutting them down. So it does not matter who owns what. Whether the trees get cut down or not depends on who values their good or cause the most.