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Solar Thermal - what labelling, if at all?

alanblaby
I've been doing a couple of EICR's recently that are on a new build estate.

These houses have 2 or 3 Solar panels on the roof, from what I can find, they are solar thermal, giving a hot water feed from the panels, as well as an electric supply to the immersion heaters.

It doesnt look like they feed back into the public supply.

There is a 6A mains supply, via a 1mm T+E, to what looks, and acts like, a programmer, for controlling the hot water heating.


Obviously there is a separate supply to the premises, from the PV panels. However, it appears it does not interact at all with the public supply.


What labelling, if any, is needed for this situation, when compiling an EICR?

Obvioulsy a 'This item is connected to the PV, and needs to be disconnected there', sited at the controls/cabling from the PV, but is anything necessary at the DB?

I would say no, as the PV supply does not go near to the public supply, apart from sharing a earth via the water tank.

Any thoughts?

Thanks.

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  • 0
    And no, it shouldn't be allowed to boil...

    Many solar thermal systems are intended to boil - as a last resort safety feature - e.g. during a power cut or pump failure - since no thermostat will turn off the sun. As long as the panel is at the highest point of the system, turning a small amount of water to steam will push all the rest of the water out of the panel itself and so prevent any more boiling (the panel is then allowed to reach it's stagnation temperature, dry). You just need an expansion vessel that sized large enough to take all the displaced water (which is why most solar systems have quite large expansion vessels even though there's often only a few litres of fluid in the solar circuit) - or as a further failsafe via the pressure relief valve.  There was an alternative approach where the circuit was pressurised to such an extent that the boiling point of the fluid was raised beyond the stagnation temperature of the panel - but that required maintaining the solar circuit at over 6 bar and as far as I know was never popular outside of Germany.


       - Andy.
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  • 0
    And no, it shouldn't be allowed to boil...

    Many solar thermal systems are intended to boil - as a last resort safety feature - e.g. during a power cut or pump failure - since no thermostat will turn off the sun. As long as the panel is at the highest point of the system, turning a small amount of water to steam will push all the rest of the water out of the panel itself and so prevent any more boiling (the panel is then allowed to reach it's stagnation temperature, dry). You just need an expansion vessel that sized large enough to take all the displaced water (which is why most solar systems have quite large expansion vessels even though there's often only a few litres of fluid in the solar circuit) - or as a further failsafe via the pressure relief valve.  There was an alternative approach where the circuit was pressurised to such an extent that the boiling point of the fluid was raised beyond the stagnation temperature of the panel - but that required maintaining the solar circuit at over 6 bar and as far as I know was never popular outside of Germany.


       - Andy.
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