As usual Google is your friend:

Solarforce

Scroll well down to find it.

It appears to be a low voltage battery cutout in order to prevent the battery being excessively discharged - it does no harm but it probably doesn't do much good either and is just another component which may fail at some point. If it were mine I'd probably remove it.

By the way, as your van is eight years old then unless the batteries have been replaced in the past couple of years or so expect them to fail within a year or so.