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When is a PEI not a PEI?

AJJewsbury

"Prosumer" Electrical Installation that is - i.e. an installation that can both produce and consume electricity.

I've been looking over the new Part 8.

It seems to describe quite a sophisticated setup - a "smart" system if you like - dynamically changing things according to some pre-programmed algorithms - maybe to minimise imports, perhaps to export 'when the price is right', deciding whether storage (if present) should accumulate or release, or something else. There even seems to be a specific requirement that a PEI incorporate an 'Electrical Energy Management System' (EEMS) (822.4).

Which got me thinking - how does a conventional ("dumb") grid-tied PV system fit into this? - where the amount of power generated locally is uncontrolled (i.e. just depends on external variables such as sunlight) and the only "management" is what can be achieved using a length of copper and Ohm's Law (i.e. any surplus just gets exported).

Is the idea that such installations should be smarter in future, or is it just that the non-existent management system of a typical PV system can just scrape through as a 'minimal' EEMS?

    - Andy.

Parents

  • but what in particular draws your attention?

    I'm really just trying to understand the general perspective - e.g. if I wanted to install a simple 'traditional' inverter-only grid-connected PV system today (now AMD2 is in force) could I do so and still claim BS 7671 compliance, or would the lack of a specific EEMS mean I would contravene 822.4? Or could I say that the requirements only demand simple control (generate every watt you can, anything not consumed locally to be exported) thus all is required is a length of solid copper and so the requirements (of BS 7671) for a EEMS are satisfied by that, or are such simple systems not intended to be covered by part 8 at all?

    It's a bit like the 'protective equipotential bonding is installed' vs 'the requirements for protective equipotential bonding have been met' debate (461.2) - in an installation with no need of bonding (because there are no extraneous-conductive-parts) the latter would be met but not the former.

       - Andy.

Reply

  • but what in particular draws your attention?

    I'm really just trying to understand the general perspective - e.g. if I wanted to install a simple 'traditional' inverter-only grid-connected PV system today (now AMD2 is in force) could I do so and still claim BS 7671 compliance, or would the lack of a specific EEMS mean I would contravene 822.4? Or could I say that the requirements only demand simple control (generate every watt you can, anything not consumed locally to be exported) thus all is required is a length of solid copper and so the requirements (of BS 7671) for a EEMS are satisfied by that, or are such simple systems not intended to be covered by part 8 at all?

    It's a bit like the 'protective equipotential bonding is installed' vs 'the requirements for protective equipotential bonding have been met' debate (461.2) - in an installation with no need of bonding (because there are no extraneous-conductive-parts) the latter would be met but not the former.

       - Andy.

Children
  • in reply to AJJewsbury
    AJJewsbury said:
    or would the lack of a specific EEMS mean I would contravene 822.4

    As you say, some form of management system would be present in the inverter, at least to ensure compliance with Regulation 22 of ESQCR. I don't think Chapter 82 dictates what constitutes an EEMS.

    AJJewsbury said:
    It's a bit like the 'protective equipotential bonding is installed' vs 'the requirements for protective equipotential bonding have been met' debate (461.2) - in an installation with no need of bonding (because there are no extraneous-conductive-parts) the latter would be met but not the former.

    Yes, a lot of questions are asked about 'main bonding structures outdoors' - yet main bonding only needs to be applied for 'each building' ?

  • in reply to AJJewsbury

    Yes I must admit I`ve been a bit vexed about the Bonding met conditions apply to a bonding not needed location too. I think we knew the intention rather than the words said

  • in reply to ebee
    ebee said:
    I think we knew the intention rather than the words said

    I think it's as simple as the fact that indoors, you transfer potential throughout a building in the wiring and other metallic services, so best to link them all together. Usually outdoors, things come into fortuitous contact with the ground - so the Earth itself provides all the required local bonding (in theory).

    Situations like EV, where the vehicle is potentially insulated from Earth via its tyres, and you might transfer remote Earth potential to it generating a local touch potential with respect to feet (or simultaneously-accessible metallic items in contact with Earth), do make us think again ... BUT if we were to apply 'main bonding' it could well simple generate a touch potential elsewhere (e.g. at the other end of a long metal fence) that wasn't there before. So overall, best to leave well alone. MOre tricky, however, with fences in places where it's necessary to bond fences for other reasons (e.g. HV installations such as substations and railways).

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