I have a 4kw system with no batteries, and had them installed since late May. June’s electricity bill was £27 and £30 in July and that’s including the standing charge. I don’t have batteries so direct excess into my hot tub, which is an added luxury that I could not afford without the panels. Yes I expect a lot higher bills in the winter but can afford what I pay just now so building up credit for when the price hike comes.