DH's work have put in a large bank of solar panels. They did the sums and found over the life of the panels it made no difference. Any savings made are needed to be put aside in order to buy new panels when the lifespan of these ones are over.

Look into the lifespan of the panels you are looking at and what there cost would be to replace them, also consider if you could afford to replace them if there was no government rebate in place.