I think the biggest difference is, the fact coal power stations turn over would drop, polluting far less.
It is a good idea and obviously southern facing for most of the sun.
the company is clever and it is for free, because they take back the extra you dont use as they dont put any storage inbetween. Because you cant store any within your home, during the summer hot sunny days, when we are working with minimal applicances on, they rake it in. You come home in evening and start to use whats avaliable.
Clever company, clever idea and lucky people who get it if you dont mind about the contract part. Everyone saves money as sunlight is free.
I signed up for another company to see if i was eligable, but i still had to pay £2000 I think but I got to keep the money i made from feeding back the grid.