Anyone got solar panels? why does our system come to life late at night?

[Finbar]

We inherited a solar panel system with the house we bought 6 months ago. No idea how it works really although I've downloaded the manual off the internet.
However, the system is located in a cupboard in our bedroom - and sometime, but not always it starts a purring whooshing noise and generally springs to life around midnight (hence why I'm up now)
Anyone have an idea why?

is it hot water, or photo voltaic?

Post some pics.

I think hot water but will get pics and the manual I downloaded.
It's quiet now! But it also comes on at. (what seems to be ) random times in the day too

I posted too soon ...its just started up again!
I think I will start logging the times

I am speculating that it is hot water and you are hearing the circulating pump. I know next to nothing about solar hw. The pump is probably controlled by heat sensors in your cylinder, pipe and panels. I would have though it would start up when the cylinder was cold and the panels were hot.

The installer's name is probably marked somewhere on a label, and in the documentation, so might be worth calling in for servicing or at least a check-over, though some major boiler manufacturers sell integrated systems and will have a list of approved installers.

Water being pumped round is usually inaudible, whooshing noises suggest air bubbles in the pump and pipes. If so, this is likely to be wrong.

Hello and thanks. It's a DeltaSol BS System apparently comprising 1 store, 1 pump and 3 sensors
I'm getting so fed up with it!