Fab thank you. I was going to put a 240ac inverter in only because it felt like a useful thing to have around. the only specific uses I could think of for it were a washing machine and dishwasher but there must be 12/24/48v versions for boats and motorhomes. If I can avoid the need for Building Regs then I will! - unless anyone wants to tell me a really obvious reason for needing 240ac that I've not thought of!!