Last summer we had solar cells installed on our roof. People asked if it was worth it financially but we felt that wasn't the point. Our concern was would it save more energy than was used in the manufacture and would the manufacture cause an unacceptable amount of pollution. There are always trade offs. After searching the web, the little information we could find convinced us that it would be worth while. As things turned out, given the current economic situation, it seems like as good an investment as any. At least it keeps paying dividends.
We have had experience with solar power. Our summer home is off the grid. That is quite a bit different than the situation in our urban home. Here we are hooked in directly to the power company. When we are not generating we get power from them. On cloudy days we generate only a fraction of what we need. On long sunny days we roll back the meter, sending the excess power to others. Since we are away much of the summer when our generation is high and people are running their air conditioning, we think we will generate more than we use. That should be the case until we are too old to handle the 9600 foot elevation of our summer home.
At the cabin the situation is a bit different. Since we are off the grid we store power in batteries to use at night or when we have a period of cloudy weather. The batteries can be a source of pollution but they last a long time and are recycled. We always try to be careful about our energy use but at the cabin we are extra careful. If I do a load of wash then we don't vacuum that day.
After four months of using more power than we generate we have started to roll back the meter again. Only on cloudy days has the meter gone up.