EPS Setup for Whole House Supply

[garypcook]

Our EPS supplies the whole house via a manual changeover switch, we manage the loads to ensure we stay below the 5kW rating of the inverter. See attached sketch - should also say we have a TT earth so don't need a separate earth rod (not shown in the diagram) .

The EPS has worked brilliantly during 2 power cuts in the last couple of weeks, however RCD in the consumer unit supplying the inverter has tripped on both occasions at some point during the power cut - I think when we flick the changeover switch to EPS. Not a problem as the EPS still works and provides power to the house but we need to remember to reset the RCD when grid power is back on otherwise we're then on pure grid power with no input from the inverter. The installer is going to look at this but any ideas why this may be the case? See sketch in EPS mode.

We also have a small neon light fitted to the changeover switch (not shown on the diagrams) to indicate when grid power is available so we don't have to constantly flick the changeover switch to check if power is back on.

[Will]

great write up, thanks for this.

[Cr125mxer]

Hi

I may be completely wrong and only now learning about these things.

As I understand it, when the inverter switches over to EPS supply it disconnects the main supply and then links the N-PE in the inverter. As you’re feeding back into the “beginning” of your main supply with the EPS supply it may be seeing some sort of small current flow Imbalance through the RCD that trips.

Like I say, I may be completely wrong but I’m very interested in the EPS setup as we can experience quite a few short duration power cuts in bad weather.

[cutlea01]

This is the setup I've wired for EPS operation in the event I want to run in Island Mode or during a grid outage:

When the changeover switch is operated, the RCD for the grid mains supply to the inverter will trip. Your above explanation seems fitting.

[SolarJunkie]

I will post a pic when I get the opportunity, but my EPS has been wired to avoid the RCD tripping that occurs.
I have a feeling that I used an MCB instead of an RCD for the PV system.
There are articles on this very topic on the web, as it is a known phenomena.

[cutlea01]

I have an RCBO in the dedicated CU for the grid supply to the inverter, which trips when the changeover switch is operated. My diagram is in post 6. I incorrectly stated I have an RCD. I'm wondering why I should need an RCBO, or any RCD type device on this circuit, as no resident at the property will be exposed to any of this wiring, and anyone touching the inverter and associated wiring should be knowledgeable. So I'm thinking to just change the RCBO to a MCB and so no more tripping? Anyone see any issues with this?

[captaincaveman]

I have an RCBO in the dedicated CU for the grid supply to the inverter, which trips when the changeover switch is operated. My diagram is in post 6. I incorrectly stated I have an RCD. I'm wondering why I should need an RCBO, or any RCD type device on this circuit, as no resident at the property will be exposed to any of this wiring, and anyone touching the inverter and associated wiring should be knowledgeable. So I'm thinking to just change the RCBO to a MCB and so no more tripping? Anyone see any issues with this?

RCD /RCBO are not just for protection of someone touching the wiring and equipment but also in the event of a fault developing with the installation and creating a hazzard which would then trip the protection instantly or trip when a person touches something made live by the fault.

[pmviana]

Hi,

I've done something similar using something like https://www.amazon.com/GEYA-W2R-3P-Auto ... r=8-6&th=1

And I've a similar problem: after a power outage the switch changes automatically from the grid to the inverter for all house as is meant to work but it also trips the breaker module that is protecting the inverter... so when the energy from the grid returns the switch automatically switches to the grid bu I need to turn on the breaker for the Inverter to work again.

Do you know how to fix this?

Best regards,
Pedro

[Reiner]

Greetings to all.

I have purchased the H3-Pro 30kW invertor for my house use.

System setup:
Mppt 1a - 12x 450W Panels West
Mppt 1b - 12x 450W Panels West
Mppt 2a - 12x 450W Panels East
Mppt 2b - 12x 450W Panels East
Mppt 3a - 10x 450W Panels South
Mppt 3b - 10x 450W Panels South
Battery: 2x 26,6kWh High Voltage Batteries.

The Invertor has two connections, Main and EPS. I believe taht the EPS output is only functional if the Grid power fails. Is this correct?
If the power supply is available the invertor would supply the energy from the PV and battery until SOC is reached and then draw power from the grid. Is this correct?
So If you hardly ever have power shortages then you do not need to connect the EPS output. Correct?

Some kind of answer would be greatly appreciated. Unfortuanitly I cannot reach FoxESS here in germany for any backup.

Thank you in advance.

[pmviana]

Yes, you're correct you only have to connect the EPS if you want to have any kind of backup from the grid otherwise left it disconnected.

The inverter turns on the EPS when there's no energy from the grid and if correctly installed will disconnect the EPS when the grid resumes.

For me in Portugal the EPS is only a nice to have, blackouts are very rare but also the cost of having the inverter using also EPS is not relevant. For me ensures some kind on independency if something happens in the grid but is not really necessary.

[origin]

Just going through the spec and install of PV, H1-6.0-E-G2, EP11 and looking for whole house EPS. I saw the US have a great device similar to some other manufacturers the 'FOX HUB G2', it seems like this is coming to the UK which is fantastic news, but anyone got more info and when this is likely to happen and can confirm it will work with the current range of equipment?

https://us.fox-ess.com/wp-content/uploa ... 0630-1.pdf

[Dave Foster]

Just going through the spec and install of PV, H1-6.0-E-G2, EP11 and looking for whole house EPS. I saw the US have a great device similar to some other manufacturers the 'FOX HUB G2', it seems like this is coming to the UK which is fantastic news, but anyone got more info and when this is likely to happen and can confirm it will work with the current range of equipment?

https://us.fox-ess.com/wp-content/uploa ... 0630-1.pdf

On last months call with Fox, they said that the new Power cube is pending certification and will be released shortly - with stock on the ground beginning of December, so very close.

There is a mention of it here approx 5.20 minutes in https://www.youtube.com/watch?v=EhRI2I1iv6E&t=324s

[origin]

Thanks for the reply Dave, but unless I've misunderstood, the Fox Hub G2 is just the "whole house backup" ATS unit (no invertor, no batteries), very similar to the giv-gateway or effectively a set of contactors/relays and a bit of magic in one box, that sits before your dist board and with a comms cable to the inverter, ct clamp on the grid, and ground spike, that automagically isolates the grid and lets you run safely off batteries and PV when the grid goes out with about 10ms delay or ideally less.

The "power cube" is the new all in one setup that sits the invertor on top of the more expensive stackable batteries.