The AP had an interesting article that I read in the Star Tribune on Sunday (but subsequently couldn't find online - found it elsewhere:  Neighbors Clash Over Trees, Solar Power)  In California, a man put up solar panels in 2001 and then sued his neighbors because their trees blocked his panels.  The trees were there before the panels were erected.  After a 6-year lawsuit, a judge ruled that two of the 8 redwoods would need to be removed because California has a law protecting a homeowner's right to sunlight.  The Solar Shade Control Act states that a homeowner can block no more than 10% of a neighbor's solar panels between 10 am and 2 pm with shrubs or trees.  This is the first conviction under the law since it was enacted 30 years ago.  Fascinating.  A spokeswoman for a local environmental group thinks the law may need to be reexamined to prevent similar lawsuits in the future.  I can't imagine being in the same situation - I don't think I would put up solar panels if my neighbors' trees were blocking them significantly... or at least I would talk with the neighbors first!