Wiring my grid-tie inverter into the DB

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  • recre8
    Junior Member
    • Nov 2020
    • 24

    #1

    [Question] Wiring my grid-tie inverter into the DB

    Hi Guys

    I need some advice from you guys about the proper way to install my 2.5kW Solis single phase grid-tie inverter into my DB board. As per the manual, the inverter should be connected in parallel with the mains (before the earth leakage) and through a disconnecting device and preferably current limit to 15A.

    Click image for larger version

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    Attached is a photo of my current DB, but I've drawn it as a diagram as well (it's a small townhouse so it's a tiny DB and all circuits are protected by EL, including the geyser).
    Click image for larger version

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    Is my understanding correct:

    - Label existing half of DB "GRID" and label new breaker(s) with "Alternate Supply"
    - Add a new mains-rated breaker (63A 2P). 10mm2 Neutral and Live tapped from Earth Leakage input. Label "Alternate Supply"
    - Add new 16A MCB. 10mm2 live tapped from new 63A breaker bottom. Label "Inverter"
    - Connect inverter using live from bottom of new 16 MCB. Neutral from neutral bar. Earth from earth bar. Surfix with 2.5mm2 conductors.
    - CT Clamp in seperate conduit to DB clamped around live from prepaid meter before mains breaker.

    Here is the diagram of what I mean:
    Click image for larger version

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    Lastly, instead of using both a isolator and MCB, can I use just a 16A double-pole MCB to function as over-current and isolator (the poles connected being live and neutral)?
  • el3venth
    Junior Member
    • Dec 2020
    • 12

    #2
    1. Treat the installation exactly like any other fixed appliance installation.
    2. A licensed electrician should install.
    3. You can use a 16A double pole to break the live and neutral.
    4. Note that the disconnect must be within the 1.5m distance from the device or the switch must have a lock-out. (see SANS 10142-1 6.16.1.4)
    5. Appropriate registration for an Small Scale Embedded System might need to be done with your local municipality. And the municipality might require a Pro/Eng to sign off, etc.
    I am not an licensed electrician and taking legal advice from an unknown (lay) person via the internet is a bad idea.

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