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Guidance for plug in solar for Electricians

Alan B

We are now a few days from plug in solar being legal. The likes of Martin Lewis is recommending people should ask an electrician to check their installation before plugging a solar system in.

I have seen various comments referring back to changes in the law and changes to the specification for a 13A plug.

But I haven't seen any guidance from IET, NAPIT or NICEIC for electricians stating under what conditions it's acceptable to plug one of these systems in.

Personally as it stands today based on what I have seen I would not be willing to say iny installation is acceptable unless it was a single socket on it's own circuit protected by a bidirectional type A RCBO. Which I am sure isn't what the government wants.

Have I missed something, is something in the pipline?

I know lots of people will just do it, but in those situations I am not responsible.

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  • 0

    Related to this topic, there was an interesting divergence between the German standards for plug-in solar and British standard which DESNZ developed, on the maximum allowed DC capacity of the solar PV modules.

    The German standards imposed a limit on the PV module capacity of 960W peak (DC) when the 800W inverter was connected using a regular Schuko plug. The connected PV module capacity could only be raised to between 960W - 2000W peak (DC), connected to the 800W inverter,  when a special plug/socket is fitted, typically the Wieland RST20i3, I understand normally this would be done by an electrician.

    Whereas the UK standards allow an 800W inverter with PV modules of upto 2000W peak (DC) straight into a regular 13A plug/socket.

    So the German standards appear to be rather more cautious, only allowing a lower PV module capacity which presumably results in a lower average (mean or median) current injected by the inverter via a regular, uncontrolled socket into the existing circuit. To raise the PV module capacity, which then presumably raises the average current injection into the circuit requires someone, electrician or other, to go through the process of checking the suitability of the connected circuit before installing the special plug/socket, which also then restricts which circuit the inverter/system can be connected to.

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  • 0

    Related to this topic, there was an interesting divergence between the German standards for plug-in solar and British standard which DESNZ developed, on the maximum allowed DC capacity of the solar PV modules.

    The German standards imposed a limit on the PV module capacity of 960W peak (DC) when the 800W inverter was connected using a regular Schuko plug. The connected PV module capacity could only be raised to between 960W - 2000W peak (DC), connected to the 800W inverter,  when a special plug/socket is fitted, typically the Wieland RST20i3, I understand normally this would be done by an electrician.

    Whereas the UK standards allow an 800W inverter with PV modules of upto 2000W peak (DC) straight into a regular 13A plug/socket.

    So the German standards appear to be rather more cautious, only allowing a lower PV module capacity which presumably results in a lower average (mean or median) current injected by the inverter via a regular, uncontrolled socket into the existing circuit. To raise the PV module capacity, which then presumably raises the average current injection into the circuit requires someone, electrician or other, to go through the process of checking the suitability of the connected circuit before installing the special plug/socket, which also then restricts which circuit the inverter/system can be connected to.

Children
  • 0 in reply to TurboGen

    an interesting divergence

    There are a number of factors at play, firstly the Germans do permit 2kW of DC input per inverter if the plug is a Wieland connector on a dedicated breaker rather than a general use Schucko socket shared with the rest of the building. There is no exact equivalent of the UK plug and socket regs, so in Germany the problem of recommending a non-standard connector in a domestic setting does not arise... (personal grump I don't know why we can't do that as well)
    However complete new circuits should  be connected and inspected by a VDE registered sparks, only DIY mods to existing circuits are permitted, though it is grudgingly understood that a lot just 'appears by magic' anyway, and is accepted 'installer unknown' so long as its safe and more or less to rules.

    It is also worth noting that  Southern Germany, especially the bits near the Alps, does get quite a lot more solar flux than we do, so the actual DC output per given panel area on average will be higher to start with,especially when compared to the northern bits of the UK.
    Also 16A German combined lights and socket circuits may be wired in 1.5mm2 or 2.5mm2, while our most common default is a 32A ring and in any case UK sockets are almost never wired in less than 2,5mm2, unless its in pyrotenax.

    Note that a  lot of German flats and bedsits have a low current (16 or 32A ) 3 phase supply, rather then single phase as it would be in the UK, so the injected current is a larger fraction of that and the supply cables are thinner.

    Mike

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