Here is a great video from EVM about how you can use home battery packs (“powerwalls”) to shift the cost of electricity from expensive daytime to cheaper night-time rates.
I have blogged before about how the case for solar panels on domestic roofs is marginal or negative but I think this solution will almost certainly have positive financial and environmental benefits.
Dr James Bayley 
Many thanks for the link, there’s a lot to think about. I’d been considering a solar panel +battery system for Spain which is a virtual no-brainer. But as a storage system for cheap leccy? Never considered it before!