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Solar supply on test reports

Alan B

How do I document and test existing solar secondary supply when adding or modifying an installation that includes solar but not working on the solar system.

I have worked on a few installations now that have main supply plus solar, I have no training on solar installations.

I look to make sure cabling looks professional and that there are isolators on DC input to inverter and AC output from inverter, use them to isolate the supply while I work.

On the test report I record that there is a second supply and that it's solar but I don't do any testing or open anything up.

Is this enough or do I need to start learning more about solar and doing more?

I haven't worked on an installation with battery but same question.

Also if I was asked to do an EICR do I just agree with the owner that the EICR doesn't include the solar installation or do I need to decline the job until I get more knowledge on solar?

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  • 0

    Actually "Island" modes, like generators and UPS's feeding final circuits as opposed to just one device,  all have the general problem that they may well be, and are intended to be, live when the mains supply is missing . At that point you have to assume that the supplier's earth is also missing - as it may be if the power is off due to an errant digger or something.  So you always need your own earth electrodes in parallel with the suppliers.

    Then what to do about N-E bonding is more complex than relying on the supplier to do it.

    If you add a bond at the inverter or generator, as you would in a stand-alone case. you may end up with two - one at your genset, and one from the supplier, or if you do not, then you may end up with none, if it happens the supply side fault also cuts the neutral off between you and the supplier's NE bond. In most single phase designs, simply operating the mains switch does this.

    Not having an earthed neutral may not matter for one item of equipment, it works OK for shaver sockets after all, but supplying into consumer units with an uncertain  mix of class1 and class II loads, and varying ADS it is not so simple. All but the largest solar installation is going to struggle to 'fire' large MCBs promptly on over-currents, and so the fault protection really relies on RCD when islanded, and that really does need an earthed neutral to work as intended.

    It is not safe to assume that all solar and similar installations have been done correctly with these factors in mind.

    Mike.

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  • 0

    Actually "Island" modes, like generators and UPS's feeding final circuits as opposed to just one device,  all have the general problem that they may well be, and are intended to be, live when the mains supply is missing . At that point you have to assume that the supplier's earth is also missing - as it may be if the power is off due to an errant digger or something.  So you always need your own earth electrodes in parallel with the suppliers.

    Then what to do about N-E bonding is more complex than relying on the supplier to do it.

    If you add a bond at the inverter or generator, as you would in a stand-alone case. you may end up with two - one at your genset, and one from the supplier, or if you do not, then you may end up with none, if it happens the supply side fault also cuts the neutral off between you and the supplier's NE bond. In most single phase designs, simply operating the mains switch does this.

    Not having an earthed neutral may not matter for one item of equipment, it works OK for shaver sockets after all, but supplying into consumer units with an uncertain  mix of class1 and class II loads, and varying ADS it is not so simple. All but the largest solar installation is going to struggle to 'fire' large MCBs promptly on over-currents, and so the fault protection really relies on RCD when islanded, and that really does need an earthed neutral to work as intended.

    It is not safe to assume that all solar and similar installations have been done correctly with these factors in mind.

    Mike.

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  • 0 in reply to mapj1

    Agreed Mike.

    For clarity, all these points are covered in the IET CoP.

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