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In the case of a power outage

  • 16-04-2022 1:23pm
    Registered Users Posts: 136 ✭✭ scunermac

    Hi all, apologies if this has been asked before but I could not find it in any threads here.

    In the case where you have solar PVs Installed, along with a Battery for storage of excess, if the power from the grid goes, can you continue to power your home from the battery?

    Post edited by DrPhilG on


  • Registered Users Posts: 5,724 ✭✭✭ Ubbquittious

    Some of those highbird inverters have an extra connector on them so you can draw about 16A from the system when the power is gone.

  • Registered Users Posts: 11,176 ✭✭✭✭ machiavellianme

    Per ESB, this is a no-no since you could inadvertently backfeed the grid and feed current into a fault or even electrocute workers repairing what they perceived to be a dead line.

  • Registered Users Posts: 429 ✭✭ idc

    Three options

    1) hybrid inverter connected to one or two sockets which run off battery during outage

    2) as above but instead of sockets connects to a sub board with a few circuits. Eg lights, sockets for WiFi, TV!

    3) hybrid configured with manual change over switch which re-enables fireman switches thus solar and battery can power house and disconnects house from grid thus won't backfeed to grid

  • Registered Users Posts: 8,697 ✭✭✭ the_amazing_raisin

    Not entirely true, you can have a backup power supply provided you have an automated disconnect from the mains in the event of a mains power failure

  • Registered Users Posts: 136 ✭✭ scunermac

    I’m guessing none of these options would be something that would be part of an initial install from the usual companies or SAAS providers?

    sound like this would need to be a bit of a DIY job done after the fact, correct?

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  • Registered Users Posts: 429 ✭✭ idc

    Definitely available from installers, my installer installed option 3. It does add to the price. No idea If saas installer does this. Option 1 might be DIYable? But options 2 and 3 will need electrician.

  • Moderators, Science, Health & Environment Moderators Posts: 4,525 Mod ✭✭✭✭ Tree

    Mine installed the backup box, there was a wait to get it in. It basically lets the inverter run in "off grid" mode. It's very fussy about what breakers need to be on it, so I can't power the lights as we've an old school no neutral loop wired mess of a lighting circuit.

  • Registered Users Posts: 3,916 ✭✭✭ mp3guy

    It's a yes-yes:

    Changeover on page 14, Section 4.9. 

  • Registered Users Posts: 8,697 ✭✭✭ the_amazing_raisin

    Any idea how that ties in with the requirements for a fireman switch to isolate the PV panels in the event of the mains supply getting switched off?

    They don't really make it clear in the document and I've been trying to figure it out myself

    My best guess is that the verbage is key, that a loss of mains isn't the same as the isolator switch being turned off in the meter cabinet?

    So if the switch is turned off then it also has to trigger the fireman switch. But if the inverter (or anti islanding box) detects a mains loss then it'll isolate the grid but keep the PV array connected

  • Registered Users Posts: 5,407 ✭✭✭ Chris_5339762

    We were told with out Eddi system it is not possible - they said the invertor needs power from the grid to run regardless of what is coming in from the PV. As yet, we don't have a battery so many that would change things but it was something I queried.

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  • Registered Users Posts: 3,916 ✭✭✭ mp3guy

    The shunt between the panels and your inverter must break the connection on loss of any AC supply to the building. The break-before-make component of the changeover switch here is key. That shunt is connected to a CB on your main consumer unit, so when a fireman rips your ESB fuse out at your meter during a fire, it breaks the DC panel connection.

    But, you are allowed to power your main consumer unit with *alternative AC supplies*, including the backup power output of your inverter. Once you changeover from ESB supply to your inverter's backup AC supply, your whole consumer unit has power, and the shunt completes the DC panel connection allowing power to flow. If you then turn the changeover switch to 0 (i.e. break all AC supply), the shunt will again break the connection.

    There's no automatic changover.

    It depends on the inverter you have. What model? Without batteries it doesn't make much sense. Eddi has nothing to do with it, if your installer suggested that find a new one going forward.

  • Registered Users Posts: 8,697 ✭✭✭ the_amazing_raisin

    Okay I think I'm following you, so say you have an inverter with 2 outputs, an uninterruptible output for backup power (output 1) and the other output will deactivate on loss of mains (output 2)

    You'd have the fireman disconnect powered from output 2 so on a loss of mains your PV is disconnected

    But you still have power via output 1 which is currently being fed by your battery (since the inverter just lost mains and PV inputs)

    You then need a manual changeover switch to switch the power of the fireman disconnect to output 1 so it gets powered again and reconnects your PV. You now have PV and battery power while the mains is out

    It needs to be manual because you should only be using it in the event of a power cut, and by default it should be set to isolate the PV

    Am I on the right track? Or have I wandered too far down the rabbit hole? 😁

  • Registered Users Posts: 3,916 ✭✭✭ mp3guy

  • Registered Users Posts: 5,407 ✭✭✭ Chris_5339762

    It's a SUN2000-3KTL-L1. Install wasn't great TBH, still teething problems a month later and I'm inheriting a mess from elderly parents who got this all installed without thinking. They asked for a 5kW inverter for a potential expansion of the new 3kW system once an extension is built - the company quoted and installed a 3kW one and no-one checked, that kind of thing. Long story.

  • Registered Users Posts: 8,697 ✭✭✭ the_amazing_raisin

  • Registered Users Posts: 5,407 ✭✭✭ Chris_5339762

    Oddly enough they were really good with the install, but getting them back to fix the final issues has been problematic as has the snaggine etc. Might post a thread on the snagging, but for example whats displayed on the Eddi for in/out/stored does not tally with the Myfusion app or the website, nor does the app/website show the hot water tank usage. All a bit silly really, but they love the system nonetheless.

    Although they whinge mightily when they see 2kW being exported!!!!