Multiple AC coupled systems

[Lincs Robert]

Hi,

Ok, so my current config is a pair of Lux Power AC units, each with some Pylons & a Chinese stack. Roughly 25kWh each, giving a total of 51kWh.id like some more capacity, easy on the battery side, but it won’t give me any more charge/discharge rate which is limited to the 3.6kW of each Lux unit.It wasn’t too much of an issue when I had 5 hours of Go Faster, but now I only have 4 hours and am limited to “only” being able to recharge to a max of roughly 29kWh overnight. First world problems eh!

The easy answer is to add another Lux as an “intermediate slave” unit, but they aren’t the cheapest and also sourcing one isn’t that easy. I’d have no issues with a used one, but apparently it MUST have the parallel label and that seems to dictate going via a reseller who will insist on installing it, which I’m quite happy to do myself.

So, thinking laterally, what’s to stop me adding a further parallel unit, say a Solis AC unit to which I add Pylons and a Chinese stack. Nothing really, except I’m not 100% sure how the two systems would co-exist. If they both have CT clamps on the incoming supply then surely I can see a possible “fight” between units and get a potential under/over import/export scenario perhaps?

Any thoughts? The easiest option would be another Lux unit I guess?

Cheers- Rob

[Tinbum]

I use Eltek Flatpacks.

[Lincs Robert]

I’ve had to think about your reply. These are AC to DC supplies I think? I’m assuming that the Solar units are doing what my Lux units are doing - you have multiple ones I think? So as far as the CT connections are concerned, if multiple, then do you have a single CT wired in series with more than one Solar? What exactly do the Elteks bring to the party please? Thanks

[Tinbum]

What exactly do the Elteks bring to the party please? Thanks

AC to DC so chargers so turn them on during cheap rate.

[AE-NMidlands]

On a similar note, I'm thinking of starting off on the pv road with Octopus fitting panels (to a w-facing roof) using Givenergy controller and batteries, though they don't have the full power-cut UPS capability, and tie you in to their/Octopus' internet control. Octopus actually said "they can be made to work during a power cut however we don't offer that service. This is expensive however, and we would only recommend it if you're in an area that gets a lot of power cuts." !

Phase 2 will be 2 more roof aspects when the life-expired tiles on them are replaced by in-roof pv...

My thinking is that a) something is going to get done at last, Octopus will manage all the formalities and trigger the request for a Smart meter and hopefully make sure it works and b) if I get frustrated by the Givenergy stuff I can do it differently next time with a different contractor, specify the kit I want - Victron and Pylontechs - to work as an independent system and just add to (maybe even replace and sell on) the Givenergy kit.

Am I missing anything important?
A

[Yuff]

My system is a year old this week.
My biggest issue, is being able to discharge my batteries quick enough, when we don’t have an off peak schedule.
I’ve looked at more storage and changing our inverter but nothing is cost effective currently( no pun intended ) as the latest giv energy batteries etc won’t work with our current system.
A gen 3 inverter increases our charging/discharging rates from 2.4/2.6 to 3.3/3.6 so isn’t really worth it

[nowty]

I use almost the same idea as the OP is thinking about and use a second standard battery inverter / charger to increase my charging power.

I added a Sofar ME3000SP (3kW AC coupled battery inverter), I managed to get one for not much over £200 second hand. I've added it in parallel to my main 6kW battery charging inverter.

I use it without any CTs in test (dumb) mode which can force charge from the grid. So in winter when sometimes I need to replenish 50kWh of battery stack in a 6 hour slot I run it to give me 9kW of combined charging power.

The test mode also has a timer and can be easily programmed to coincide with the cheapslot.

[Yuff]

I use almost the same idea as the OP is thinking about and use a second standard battery inverter / charger to increase my charging power.

I added a Sofar ME3000SP (3kW AC coupled battery inverter), I managed to get one for not much over £200 second hand. I've added it in parallel to my main 6kW battery charging inverter.

I use it without any CTs in test (dumb) mode which can force charge from the grid. So in winter when sometimes I need to replenish 50kWh of battery stack in a 6 hour slot I run it to give me 9kW of combined charging power.

The test mode also has a timer and can be easily programmed to coincide with the cheapslot.

I am in the hands of my installer as he is saying the cheapest option is to swap the inverter but it only gets me a discharge of 3.6 kw and ideally I’d like to get to 5 kw discharge if possible. The charging side is not an issue with the extra IO off peak schedules.
GivEnergy are saying the gen 3 inverter is my only option but it doesn’t seem worth the extra cost

[Lincs Robert]

The Lux system is modular, with each AC coupled unit giving an additional 3.6kW of charge/discharge capability - subject to certain conditions. I have 2 at the moment, and am awaiting delivery of the 3rd unit. I’m actually on a coffee break at the moment getting everything prepped for its installation in the next week or so. I’d recommend investing in the extended warranty on Lux units. Of the existing units I have, they have both been replaced under warranty. The original one in 2019 suddenly stopped working after a few months, the new one from early 2022 developed a weird fault which blanked the top half of the LCD screen, but otherwise worked normally! My brother also has a pair of these, which both failed following a lightning strike. It’s a shame that the end user can only undertake limited activity- but can accidentally restore factory defaults, I did it! The UK distributor can also be a bit unpredictable to deal with. I had an issue with highish grid import (75w or so) whilst discharging overnight. The distributor say it was ok as the system reported zero import. I then flagged it to China who tweaked a CT calibration setting & it’s been fine ever since. It’s a great shame as customer service is key with modern tech. Hey ho.

[Sim_C]

The Lux system is clearly designed to support multiple AC coupled units running in parallel.

A few people on the GivEnergy forums have 2xAC-3 units, but it is not a supported solution, and they have issues with cross-charging between units at times. A central control unit to overcome these issues has been 'coming soon' for a long time now.

I think mixing and matching with multiple manufacturers is just asking for trouble, as they will have different response times to changing load conditions and are likely to cross-charge.