An interesting case in California puts a complicated question: Which one is greener, trees or solar panels? Neighbours Richard Treanor and Mark Vargas were locked in battle for six years because Treanor's 35-foot oak trees, planted over a decade ago, shaded Vargas' solar panels. In this case, the court ruled in favour of the solar panels because of California's Solar Shade Control Act, a law passed in 1979 and not applied until now. Treanor was not fined but must cut down his trees until March 28.