Was on my computer earlier looking at grid injection and battery backup for PV, while chatting with a friend about manufacturing an automatic transfer switch for going into standalone mode when the grid goes down (changing to local earth, then synching the local AC sine wave to the grid before rejoining). The cheapest of off the shelf solutions costs over €1,000 so we're looking at a partnership to do it ourselves.
Then the grid went down as we were discussing it. The whole area is affected for at least five hours. Need to get that battery backup sorted out..