You need to do your sums i.e.. how much will you need to invest to make sure you get something that does look like a return and how long does it need for that return to pay off the investment.
Solar panels are good when a) there is enough sun exposure (your roof needs to be a certain angle to maximise the exposure, it is better if you are south or south-west facing obviously and you need a lot of sunny days). Then b) how much is it going to reduce your electricity bill.
The technology is evolving everyday and i am sure the future will bring a solution but at the moment the biggest problem with sustainable energy is storage. Until we can store the energy it is not going to be that cost effective unless you live in a very sunny region of the world, I presume you are in Battersea hardly a sunny spot