We're thinking of getting some fitted where the company installs them free of charge. This company own the panels but you get free electricity. It estimates that energy bills will be halved, any excess elec that you don't use goes back into the national grid which is where the company make all the money. They do all the maintenence, etc.
Website is here and they have lots of FAQ and I can't see any drawbacks apart from the fact they look ugly. Was worried it may put off potential buyers in the future but my brother reckons people would be more likely to buy a house with this.
www.ashadegreener.co.uk/our-installations/