The right inverter for battery storage and some other Qs

[Oldgreybeard]

I really hate to be the bearer of bad news, but that looks to be an unsafe installation, I'm afraid. First observation is that there is no RCD protection at all on the inverter circuit, it seems to be connected to an MCB, when it must be connected via an RCBO. Easy to fix, the MCB (circled in red below) just needs to be swapped for an RCBO (at the same time the cable rating needs to be checked - 32A is too high to protect any cable under 4mm²):

MCB - needs to be an RCBO.jpg (74.71 KiB) Viewed 956 times

The other major fault is that there are exposed single insulated conductors with wagos that can be flipped open very easily to expose bare (and probably live) wires. Again, easily fixed, they just need to be put inside the trunking and the trunking secured so that the lid cannot be removed without the use of tools:

Exposed conductors.jpg (103.67 KiB) Viewed 956 times

Final major fault is that there are no blanking plates over the open slots at the left of the CU. Anyone could poke their finger in there and touch the live busbar. Again, easy to fix, just needs a couple of blanks to be fitted.

[ducabi]

I really hate to be the bearer of bad news, but that looks to be an unsafe installation, I'm afraid.

Have you just started or that's it? There is also no DC switch between batteries and inverter.
But my bigger worry is smart meter showing export when i switch to discharging batteries. Is this correct way of battery working or they messed up something?

[Oldgreybeard]

I really hate to be the bearer of bad news, but that looks to be an unsafe installation, I'm afraid.

Have you just started or that's it? There is also no DC switch between batteries and inverter.
But my bigger worry is smart meter showing export when i switch to discharging batteries. Is this correct way of battery working or they messed up something?

The exporting to the grid thing isn't a major safety issue, whereas all the other things mentioned are - they could kill someone. Chances are that the CT has been installed or setup incorrectly, and so isn't restricting grid export as it should.

A DC switch isn't essential, as the batteries do have switches to turn them off, but DC fuses are needed and it makes sense (IMHO) to combine the fuse requirement with a switch, as discussed earlier. The "Frankenstein" switches that include two blade fuses are a good option, as they provide both functions in one unit.

Sorry to seem a bit negative . . .

[ducabi]

The exporting to the grid thing isn't a major safety issue, whereas all the other things mentioned are - they could kill someone. Chances are that the CT has been installed or setup incorrectly, and so isn't restricting grid export as it should.

A DC switch isn't essential, as the batteries do have switches to turn them off, but DC fuses are needed and it makes sense (IMHO) to combine the fuse requirement with a switch, as discussed earlier. The "Frankenstein" switches that include two blade fuses are a good option, as they provide both functions in one unit.

Sorry to seem a bit negative . . .

The lovely wagos were my first red light until I saw the export on smart meter. How can I check/amend CT? I can deal with wagos myself not sure about RCBO.

[nowty]

Also, preferable to have a small airgap between the batteries with some sort of spacer.

[Oldgreybeard]

The lovely wagos were my first red light until I saw the export on smart meter. How can I check/amend CT? I can deal with wagos myself not sure about RCBO.

Might just be that the CT has been installed the wrong way around, so is sensing export as import. The Sofar inverter I have autodetects the CT, but must be started up initially with no PV generation, so it can detect the direction of import/export correctly. Once it's done this it needs to be locked from the menu, so it remembers which way around the CT is if there is a power failure.

Tucking the wagos into the trunking is a part of the fix, but if there are connectors inside trunking then the trunking needs to be secured so tools are needed to take the lid off and access them, I believe. Lots of easy fixes for that, wago boxes have little loops to take cable ties, and as cable ties have to be cut with tools to remove them that meets the requirement for secured access. My fix for connectors inside plastic trunking is to just fit a couple of threaded pillars inside and secure the lid of the trunking with screws. That meets the "use of tools" requirement. A cable tie or two around the trunking would also meet that requirement, but looks a bit less tidy. Metal trunking is fine, as it has screws holding the lid on.

The RCBO should be a couple of minutes work to swap. Needs to be rated to protect the cable to the inverter though, so 16A or 20A if the cable is 2.5mm², as I suspect it may be from looking at it. Only issues with swapping the MCB for an RCBO are making sure the power is off and checked to be really isolated before doing the swap, plus torquing the terminals to the correct value (1.2Nm for those Fusebox RCBOs).

Edited to add:

List of bits that may help:

20A RCBO (assuming that the cable to the inverter is 2.5mm²): https://www.consumerunitworld.co.uk/fus ... 4026-p.asp

Blanks to fill the two slots at the left and prevent anyone touching the busbar (two needed): https://www.consumerunitworld.co.uk/fus ... 4029-p.asp

[ducabi]

Also, preferable to have a small airgap between the batteries with some sort of spacer.

Yup, I'll put some small pieces of wood

Might just be that the CT has been installed the wrong way around, so is sensing export as import. The Sofar inverter I have autodetects the CT, but must be started up initially with no PV generation, so it can detect the direction of import/export correctly. Once it's done this it needs to be locked from the menu, so it remembers which way around the CT is if there is a power failure.

Does this qualifies as wrong way around?!
So, I don't have PVs at the moment, is it just a matter of plugging it before henley block?

[Oldgreybeard]

The CT is supposed to be on the meter tails, so it can sense whether the whole house is importing or exporting. My guess from that photo is that it's in completely the wrong location. I had to run a long cable from the inverter around to our meter kiosk so I could fit the inverter CT around the tail on the meter, my guess is that you may well need to do the same unless the meter is close by.

[AGT]

Aren’t the wagos for the generation meter.

[ducabi]

Aren’t the wagos for the generation meter.

They are but i have no PVs.

So, in terms of CT. I connected it before henley blocks. Why isn't it working? Is there a way to check if it's connected properly and working? I've already tried both sides.