Demountable camper group

Thats a good starting point, if you hook up a meter to panel output direct, even in shade you should get 12V never mind the controller

The plugs are almost impossible to mix up, so it must be where it enters controller, (mine are really fiddly)

Correction ! I had my leads on my tester back to front .
Still got 1.75 volts when everything is connected between panel and controller . 19 volts off the panel if disconnected from the controller .

is that -19V off panel Jim?

well this is your panels info sticker

Yes . That is the same as mine.
Jim

Is everything wired in place - i.e. the controller wired to the batteries as well as the solar?

Make sure you have connected the battery to the correct connections - these Chinese controllers tend to have 2 outputs - a battery charge output and a load output. The load output is for when you have solar power coming in but the battery is already full, so it can run some additional thing, like a small water heater, with the spare solar energy.

If not properly connected to the battery there is a chance that the electronics in the charge controller are scavanging power just to operate in idle from solar rather than battery, hence pulling the voltage down.

The voltage you are reading - is that with direct sunlight on the solar panels? Indoors they will still produce an open circuit voltage of around their maximum because nothing is pulling that voltage down drawing current. The moment you connect them to anything that will draw current you get a more realistic view of the solar power getting into the panels. And if indoors that will soon pull the voltage right down, but in sunlight there will be enough power to maintain the voltage.

Also check the connectors carefully. You could have a bad connection that is sufficient to show full voltage, but when anything tries to draw current pulls that voltage down because the connection prevents the current from flowing.

Steve.

Connection is everything on these, my controller for example, its domino type screw connections were barely able to house the gauge wire I had that and manipulating the wire around in a curve to get into position as well

and usually with electrical it's something simple i've overlooked or a poor connection made.
So work back through those first is my 2p worth anything like me it will be that Jim

Thanks for the replies .I am working away for a few days now so I will go through it when I get back . I messaged the seller with the symptoms . They replied " shall we send another controller ? " . I have said yes just in case it is that .
Jim