On-grid domestic battery storage

joefizz

mmmmikey wrote: »

A couple of minor teething issues, like erring too much on the side of caution with the input MCB, which tripped when the charger started at 01:30 this morning. Complicated by the fact it also tripped the garage roller shutter door circuit so I had to manually wind up the door to get to the consumer unit and reset the MCB. Problem solved with separate circuits and a more appropriate MCB - we live and learn

I had a similar MCB issue in the summer with two spare freezers running off the same 16A mcb. Hot weather, brownout/surge (only confirmed today) and one of them tripping the MCB meant they both sat for a month without power....

Now on separate MCBs and that older one replaced.
Strangely enough (I mentioned I dont believe in coincidences) the kitchen ring main MCB tripped yesterday with only a fridge and freezer on it.... might have been the precursor to todays larger failure... hmmm... might have to replace that too!

mmmmikey

We had a brief power cut at lunchtime today, but I didn't notice it at the time because I was in the lounge watching the battery powered TV and with the battery powered lights on. I may not have noticed until much later if one of my neighbours hadn't come round and asked me if my power had gone off. Feeling pretty smug



The new battery system is now fully operational and working well, easily powering the fridge, half of the lighting, TV, computer system with plenty left over to heat the bedroom with the ASHP in the evening. Charging the battery overnight means that the battery/ASHP combination is probably one of the most efficient night storage heaters that money can buy.


joefizz - you may want to check this out, it's working really well for me and I reckon it's something you could put to good use....

https://www.photonicuniverse.com/en/catalog/full/178-3000W-48V-low-frequency-pure-sine-wave-off-grid-inverter-peak-power-9000W.html

Zarch

Install type question.

Are there any limits on the distance the batteries can be away from the inverter / consumer unit etc?

I've got little to no room where all that is stored, but I could make space elsewhere.

Is there a cable length limit?

1961Nick

Zarch wrote: »

Install type question.

Are there any limits on the distance the batteries can be away from the inverter / consumer unit etc?

I've got little to no room where all that is stored, but I could make space elsewhere.

Is there a cable length limit?

What sort of distance to the CU are you contemplating?

There's definitely no problem with the power cable, but I think there's a limit on how much you can extend the cable to the clamp.

1961Nick

I've been right through the manual for the ME3000SP & I can't find anything about a maximum length for the CT cable.....just how to extend it.

It looks as if this inverter could be mounter anywhere in your house.

joefizz

mmmmikey wrote: »

joefizz - you may want to check this out, it's working really well for me and I reckon it's something you could put to good use....

https://www.photonicuniverse.com/en/catalog/full/178-3000W-48V-low-frequency-pure-sine-wave-off-grid-inverter-peak-power-9000W.html

Cheers!
Was looking at smaller 600W pure sine wave units yesterday funnily enough. My theory is that I dont need to be able to drive everything but just enough to power the solaredge to think its connected to the mains. At the last power out I tried my old 300W inverter but its not pure sine wave (old one, works with laptops etc or most things with a psu) so it didnt work.
The theory is, isolate from mains coming in and run everything else as normal off a bank of 2-4 12v lead acid batteries fed by two 20W smaller panels (will be adding a 100w flexible panel to the campervan as part of the refit). When the camper is refitted, it can also just plug into the house and act as a 'mains reference' supply from its leisure batteries.
Effectively it only needs to be powerful enough (and good enough output) to fool the rest of the system into thinking mains are connected.

Ive the sofar inverter for the pylontech batteries so it can drive the house (as last week) but when the charge is done its done and the solar panels are off. I'm looking a way of keeping the whole lot going/charging during daylight/solar production if the mains grid is off.


Ordered a cheap pc based oscilloscope yesterday to check waveforms. Ive about 3 older inverters lying around and would rather modify those to pure sine wave than buy something new, but for the sake of a hundred quid... but then this is MSE ;-)


With your link inverter I could put a switch on half the pylontech batteries (split it into two feeds) and use those with the inverter in your link, that way it would still power the solar inverter and charge the other two pylontechs via the sofar inverter... or just get another sofar.. or... this is getting complicated ;-)

joefizz

Zarch wrote: »

Install type question.

Are there any limits on the distance the batteries can be away from the inverter / consumer unit etc?

I've got little to no room where all that is stored, but I could make space elsewhere.

Is there a cable length limit?

To follow up on Nicks post the inverter/battery combination can be put anywhere, as you mention its the distance the CT cables that run to the consumer unit that can be an issue.
If you use CAT 5 lan cable and twisted pairs (twist ends of two of the coloured internal 5 cables together to form one conductor/cable) you should get a reasonable distance out of it. Id say 10-20m is probably fine.



I put mine in my spare room which is pretty much the thickness of the wall away from the CU so thats not an issue and the inefficiences exhausted as heat help to heat up the room ;-)


If you are using DC connected battery though I think they have to be reasonably co-located, i.e. as close as possible (2-3m max), separate ac inverter/batteries can be put anywhere.

mmmmikey

Because the connection between the batteries and the inverter are low voltage / high current you may find that the power loss in the cables will become a consideration if you make them very long. As a general rule, the shorter and thicker these cables are the better - i.e. in terms of performance the most significant thing here is the cables between battery and inverter.



Another consideration is safety, labelling and consideration of where you put isolation switches. I think it would be a good idea to get professional advice on this - it's not just a question of making everything work which is easy enough but also making sure it is done in accordance with relevant best practice guidelines. I don't want to go all nanny state here, but this is particularly important if the equipment is away from the consumer unit as it becomes less obvious to anyone working on your electrics that there is battery equipment installed that needs isolating.


I don't think either of these considerations are insurmountable or expensive to resolve - just a question of a bit of extra planning and appropriately sized cables.

joefizz

mmmmikey wrote: »

Another consideration is safety, labelling and consideration of where you put isolation switches. I think it would be a good idea to get professional advice on this - it's not just a question of making everything work which is easy enough but also making sure it is done in accordance with relevant best practice guidelines. I don't want to go all nanny state here, but this is particularly important if the equipment is away from the consumer unit as it becomes less obvious to anyone working on your electrics that there is battery equipment installed that needs isolating.
.

This, this, this!
Ive a sticker inside the window near the sofar/pylontech, well you know, just in case the fire brigade might want to know....
...should really put it on the outside...

mmmmikey

p.s. as an afterthought if you want good advice on this, try


https://www.solarfixer.co.uk/


The guy that runs this business (Geoff) will do a good job at a reasonable price and not try and persuade you to do loads of unnecessary work. When he installed my PowerVault he did a bit of tidying up of the wiring for the solar installation and re-labelled everything properly and I was very happy with the work he did and the price he charged. He won't charge you any more than a regular electrician but has the technical skills and background to properly understand what needs doing.