This was just a little project to add a bit of power to our cabin and workshop. Both buildings have mains electricity installed for lighting and sockets, but this is connected to the main house by a detachable cable on a separate RCD circuit. The normal situation is to have these buildings disconnected from the mains completely which if you just a five minute job to do late at night can be irritating. Hence the installation of 12V batteries, inverters and solar panels.
The bottom line to this was that we planned to buy new batteries for our motorhome, and would recycle the old ones into the role until they were dead. We also had two solar panels from a previous upgrade on the van as well, so we were well on the way to doing this without buying to much.