Solar Panel Question

Triangle

We have a Kingspan 30 tube system installed and i believe it's started acting erratically and am looking for some help (not even sure if this is the right forum but would appreciate any help available)

The Issues as I see them are

1) Pump running 80% of the time (mostly at night)
2) Solar Controller showing temperature of 90 degrees at 1am on top of the panels while temp of the tubes is ~25 degrees
3) if the controller is switched off and on again, it 'corrects' the temperature on top of the panels to a more reasonable temperature.

4) (and less measurable) it just doesn't seem as efficient as it was last year when it was installed.

Could it be the thermostat or the controller broken?

One of the reasons i was given was

'Other cause may be heat syphoning out off solar coil. In that case you would need to put 10cm anti-gravity drop in solar pipework on flow to coil.'

but this doesn't seem to tie in with the fact a reboot resets the temperature.

Any help is appreciated as I'm feeling like I'm getting fobbed off with excuses that don't seem logical - Keeping in mind I have no technical experience in Solar Panels - it just could be me

Thanks

nmacc

Check that the sensor hasn't fallen out of the bottom of the cylinder as this would give a persistant reading of 25 degrees for the thermal store.

It wouldn't explain the 90 degree panel however. The system could be low on fluid. See if you can find the solar pump which will have a pressure gauge attached. The pressure should be above 1 Bar. If less than that there may be air in the system preventing the pump from circulating the heat from the panels.

After that it's a possible faulty sensor or controller.

Triangle

Thanks for the reply Nmacc.

The Thermometer's are in place (held with tape)
The pressure is at 2 Bar - should be at 3 bar but they lost some fluid during installation.

I'm going to go back to the installers and insist they investigate. Thanks for taking the time to reply.

nmacc

I have come across several cases where the pump is airlocked, even though the pressure is high. The tell-tale is that the pump gets very hot and will eventually become noisy.

This could be one explanation of the way the system 'resets' when power is interrupted. With the power off the airlock moves out of the pump and allows it to circulate for a while.

First job is for the installer to flush the system to clear out any air.

shane0007

Sounds more like a faulty PT1000 roof sensor.
Also system pressure should not have been set at 3.0bar pressure, unless the head height from pump station to collector manifold is 20m high.
It should be 1.0 bar plus 0.1 bar for every meter of head height. Expansion vessel should be 0.3 bar below system pressure.