Isolator to use PV&battery when grid off

Hi
I have existing Solar Edge panels on garage and have just added more panels plus GivEnergy inverter and battery onto the house.
I would like a solution that on mains failure, the loss of grid supply is auto detected and a grid isolator opens. This will then allow the inverter to continue to run the house on any generated PV and any battery charge.

This will also fill 'gaps' if we get power blackouts this winter.

I would like to fix an indication light on the grid side of grid isolator. When grid goes off, the light goes off and that will warn me not to run the big power consumers such as washing machine, dishwasher and oven. Rest of house is LED lighting and LED TVs etc - so all pretty low consumption.
When grid goes live again, the indication light will come on, and I can manually reinstate the grid connection.

Does anyone know if there is an auto break grid isolator that will open before the inverter starts to feed back into the system and possibly grid (as the PVs could be producing)

Regards
Steve

SteveCook Don't know anything about Solar Edge but the Givenergy inverters will automatically disconnect themselves from your house consumer unit (CU) on mains failure. They will only reconnect to the grid when the mains voltage is restored at 240V, 50Hz. The Givenergy inverters have an EPS (Emergency Power Supply) feature which supplies attached load continuously during normal grid operation. In the event of grid disconnection, the EPS also disconnects but re-connects automatically within a few seconds. This supply can be configured (by Givenergy) to act as an Uninterruptible Power Supply if you ask them, where it does not disconnect when grid is lost.

The output from Givenergy EPS is limited to 2.5/3.6kW (gen1/2) and you cannot connect two inverters on EPS to increase total capacity. If you have more than one inverter, you can connect their EPS to supply different circuits/CUs. You can connect the EPS via automatic or manual changeover switches to supplies.

To do what I think you want, you would need to have a (manual) changeover switch(es) between your DNO meter and the house CU that would isolate the grid and the normal Givenergy inverter connection and allow you to feed the CU from EPS. The wiring isn't difficult but you would be able to eek out your battery charge better if you just had a double switched socket off the EPS and plugged into that, the things you really want to power during a power cut: a light, router; gas/oil boiler, maybe TV. Whole house supply is possible but who wants to power all those phantom loads off battery when you're trying to survive a power cut?

Tim
Thanks
I have thought about using sockets, but i need power for the boiler plus circulation pump(s) as I have a thermal store.
Control of all the rooms is via a network system, and the house is a bungalow, so it is a long way to be trailing cables to power all the things for a bit of operational comfort when mains is off. For that reason I want to keep feeding via the CU.
The lighting is all via a lighting control system and Rako racks, but all LED and all goes off on mains break and on mains reinstatement comes back on in an "off" state.
Parasitic loads are about 400w total for the house, so battery could do 20 hours with no PV input.
I am just trying to cover 3-4 hour breaks and possible short winter shut downs.
So what I want to do is feed the CU via a currently spare breaker via the EPS and I can manually shut off anything I dont want by seeing the mains indicator light.
I need a mains breaker on the incoming supply that drops out on mains failure before the EPS kicks in.
This will then allow the house to run on battery and PV ( and i shut down the big stuff).
When the indicator light comes back on, the breaker will be able to be manually closed and put house back on grid supply.

Regards
Steve

SteveCook I need a mains breaker on the incoming supply that drops out on mains failure before the EPS kicks in.

Simplest would be to have a simple manual double pole (break-before-make) changeover that switches CU supply from grid to EPS. Just need to watch that CU is adequately earthed when running from EPS and that CU load under EPS cannot exceed inverter output otherwise damage could occur.

Tim
Sorry I am a mechanical enginner not electrical, but i do have some knowledge after 40 years in consultancy.
If i use the EPS autos feeds into the CU, I need some way to auto open a main incoming supply and break it before the EPS kicks in, otherwise the battery and PVs can backfeed the grid
I am trying to find a mains breaker with a relay coil that holds it 'in' when there is mains power and needs a manual reset when the incoming mains light glows again.

Do you know of such a product please.
Regards
Steve

These are the supported configurations for EPS

https://kb.givenergy.cloud/article.php?id=12

I guess you want to feed the inverter from a grid consumer unit, but then have the EPS on the inverter connected to an EPS consumer unit.

Have the essential circuits on the EPS CU and the rest on the grid CU.

Hopefully those EPS side circuits will never go over the EPS output limit. Don't want to kill the inverter!

ABB SACE range - commonly used with add on shunts to open or close on demand. AD or DC loads. Big and expensive. I use them to disconnect batteries via node-red on errors (bms etc) https://docs.rs-online.com/69f0/0900766b806b43ca.pdf

TX200 Thanks but the EPS loads are also normal loads and I need to break them from the grid connection when on mains failure and on inverter EPS

I wonder if an auto generator changeover switch could do what you need?

If you disconnect the grid supply you will likely lose your earth as well, depending on the earthing system you have - this is why Ge EPS systems are so pedantic about earthing arrangements.

SteveCook the inverter supplies grid power to the EPS circuits until the grid fails, then it switches to supply the EPS from the battery instead.

TX200 Ah right. I did not know that. I assumed the EPS side was dead until grid failure and then went live.

So are you saying that anything fed from the EPS side is always live and then automatically separated from the grid by devices inside the inverter on grid failure, and at the same time the non EPS stuff just goes dead?

So if i had a small CU with boiler/controls ,lights and a bit of power (say lounge and kitchen fridge/freezer) on the EPS, then on mains failure everything else would drop but they would carry on.

As above, but you’ll also need to make sure there is an independent earth on the eps side, as grid earth will be disconnected during a power cut due to the islanding of the GE inverter.

With regards to the solar edge inverters, I’m not familiar with those, but suspect they are grid tied and thus won’t work in a power cut.

If the PV went into the GE inverter as DC, e.g. using a hybrid GE Inverter, then solar power should continue to be available in a power cut. But with the AC GE inverter, solar would be down until the national grid was back. Unless there’s some complicated way around this (there are some discussions elsewhere in the forum about this I think)

One other thing to think about, is if your inverter develops a fault, you'll loose the essential circuits till it's repaired or till you get an electrician in to rewire.

Thus it may be a good idea to have a manual changeover switch that allows your "EPS consumer unit" to be fed by either EPS from the inverter OR from the grid i.e. from the main consumer unit.

TX200
Thanks. It is the GIv-HY 5.0 inverter so that will carry on working with the batteries and PVs that feed it.
The SolarEdge system will be on a CU that will not be on the EPS CU, so that will all drop off.

TX200 grid earth will be disconnected during a power cut

@SteveCook The earth may be disconnected; it depends on how the installation is earthed. A competent electrician would be able to advise and install an earth rod or other compliant solution.

With the circuits you are looking to cover from EPS, if you are able to route them out to a separate CU, then a manual changeover switch (enabling connection to EPS in normal mode or grid in maintenance mode) would be sufficient. If that's too much faff, then a double switched socket would do as a temporary measure. We have this latter fix with the broadband/VOIP plugged in. If we have a power cut lasting for more than an hour or two, I'd run an extension cable to the boiler to get that back. If it lasted a couple of days, it'd give me time to install something more permanent for the boiler and maybe a table lamp.

Tim
Tim
Thanks
I have spent all day messing around with circuit wiring and CUs and now have a dedicated CU that just feeds lights (all LED), fridge/freezer, boiler, smoke detectors, burglar alarm and lounge sockets (TV and skybox).
That will now be my Essential CU and eventually be fed from the EPS output from the inverter when the electrician that installed it comes back from holiday.
He can check earthing then.

For now the Essential CU just runs on mains as before.
Regards
Steve

Hi Steve, I'm currently in the process of getting prices in to have my system wired to something like what have. Have you retained the 32amp RCD's? As one company has recommended to replace them with 13amp
Kind regards
Steve