One of my drinking Pals was quick off the mark to instal Solar Panels on the roof of his house. He claims he got his money back (ie return of investment), in 7 years. However, that is largely (if not totally) due to him being an 'early adopter', and getting a generous "feed-in tariff". Effectively, other consumers subsidised his solar panel installation, via "green levies". Current "feed-in tariffs" would produce a Break even point of ore like 20 years.
Bearing in mind were we (myself and my Pal) are located (ie North East England), the output from his solar panels is paltry for much of the year (last week he did not even get 100w/day total output).
So, although, "every little helps", I cannot see that his solar panels are going to save the Polar Bears.