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Following on from the snuggy inverter thread,

Which inverters out there have the potential to charge batteries from the grid fastest with amp draw vs kwh.

Im looking at victron, either multiplus or quattro, but are there any others that have the larger capabilities?

As i am on agile import, and happy with it, (years average 17p/ kwh) What matters most, is being able to fill the batteries (45kwh currently) as fast and cheaply as possible.


im on fixed 15p/kwh export, and obviously with a fixed price It doesnt matter so much about higher discharge ability, as the DNO, SSE may restrict me to 3.68kwh when whatever request is put in.

I plan to maximise solar to reduce the bills and top the batteries up, but take advantage of being able to produce income via export, whilst the ability still exists.

I have a feeling this is something that will soon change, so want to maximise what i can now.

Unsure if that looks like going all DC coupled, or a mixture of AC and DC or what, yet.
I have a feeling the 8kwh quattro will do all i want, fast enough, and handle the houses demands, but with a CT clamp to reduce export to whatever the DNO demand.

Is there anything else, close to it out there, without spending even more money?

I’m not an expert here but isn’t your connection to the DNO the limiting factor rather than the Inverter?

Just thinking of some of the forum members who run power stations with large storage and the mentioning periodically of warm / hot DNO tails and fuse.

Happy to learn so I will read what others counsel.

Moxi

You can also use supplementary battery chargers to get really high charge rates if the spec of your batteries, cables, isolators, etc can take it.

I use a second hand Sofar ME3000SP in dumb mode to get an extra 3kW charging capacity on top of my SMA Sunny Island 6kW capacity. Comes in handy sometimes in Winter.

I think Tinbum and some others use Eltek Flatpack battery chargers, there is some info on threads on here if you search for "eltek".

Sunsynk 8kW model can charge at 190 amps

Nowty will give a far more precise answer but if you have 45kWh of batteries (and hence can dump a lot of current into them at any one time), and the question is about grid charging specifically (as related by the agile comment) it is going to come down to AC charging efficiency and inverting capacity. Export limiting is irrelevant when considering this aspect of system building.

The efficiency you can find out from reading literature but most efficient charging usually happens between 40% to 70% of the max inverting capacity, and the inverting capacity is in the title. You then need to be able to control the AC charging rate (so how are the apps? etc)

DC coupled solar will force you to export as you top out on battery charge but this us far more efficient, but unless you do nowtys and Joeboys million string process with lots of separate charge controllers it's the only way to max out generation. My advice is work out where each string goes and then work out which strings you want to be AC coupled and which ones should be DC. You need both, and it's actually simpler to put out one big AC coupled inverter to try and get the DNO to agree to a higher discharge limit. You will also need to think about asking the DNO to fit a larger main fuse as a large inverter (say Victron 10kW inverters) plus an oven and EV charging could exceed a 60A main fuse. Might want to do this before some of the other stuff so they don't snoop.

Finally, some inverters (luxpowertek) have home assistant addons which give control over export limits. I only found this out by accident and I see many potential problems but just stating it here for information.

nowty wrote: ↑Sun Jul 07, 2024 2:12 pm You can also use supplementary battery chargers to get really high charge rates if the spec of your batteries, cables, isolators, etc can take it.

I use a second hand Sofar ME3000SP in dumb mode to get an extra 3kW charging capacity on top of my SMA Sunny Island 6kW capacity. Comes in handy sometimes in Winter.

I think Tinbum and some others use Eltek Flatpack battery chargers, there is some info on threads on here if you search for "eltek".

Speak of the devil...

Nora, if a house uses, say 18kW of power, and AC charginge/discharge cycles are 75% efficient, then plan to charge 24kW. With a 8kW charger that's 3 hours of charging, or 6 cheap slots. Is that enough come winter? The other point is how the power is discharged back to the house: if its discharged mostly at a slow rate, then a larger inverter is actually less efficient and its better to have multiple smaller paralleled inverters, use all for charging buy only 1 for discharging except for the few high use times such as cooking when you can turn on the second inverter. I've found this has been far more efficient but you need wall space and to stay on the ball. Can be hard when other household members don't play the game.

Theres only me and the OH in the house, and i do the cooking etc, so that he is fed when he gets through the door each night.
Very rarely will the need arise for large draw appliances to be on unless i am controlling it.

Main fuse is 100A btw.

I had hoped, to find an electrician who could advise/ on what exact set up would be best, but i am struggling to find one who is either not crazy busy, or wants to do such a "small" job.
Ive even tried throwing the incentive of installed panels in, but because they are to go on a vertical wall, its met with groans.
No one up here has the time and/or inclination to just do a bare bones set up. Everyone seems to want to sell me a tesla powerwall or similar .
Ive even tried coaxing by asking for pylons to be installed as the battery of choice, to then suppliment the EVEs.
Its like pulling hens teeth to even get anyone round.

I had thought of going the multiple inverters route, instead of a large one, but i dont think im thinking of its operation correctly, and the charge rate into the batteries has hindered my thinking each time.

Thanks Nowty for stating the bleedin obvious, a secondary charger can spread the load and charge faster.

I had wondered, given the inability to find a sparky as yet, if i could do it myself within the G98 rules and swap the solid for a hybrid., keep the existing grid tied and the rest DC coupled.
Whats turned me off is 1, i want to utilise UPS which iirc needs DNO approval, and 2, the charge rate each time, which seems to not actually be an issue given the bleedin obvious being stated!

Im not incapable of doing the install, especially given the bones of the grid tied system is already there to work from.

Last winter, grid draw was rarely over 3.6kwh at any one point with everything i needed going, but the ASHP does make it a bit harder to keep to this in colder weather, hence why i was thinking a 5kwh inverter would be better.
If the batteries have enough charge to deal with the full house load at 5kwh, even if only needed for 30 minutes, id rather draw from the battery than draw the rest from the grid.

Its more the DNO application that i dont want to deal with and the technical drawings they require if i have to inform them.
They were rude enough when i enquired if it was okay to swap the "broken" inverter over to a different make within the confines of my existing g98 or if i would require a new submission, telling me they would only speak to a qualified, registered sparky regarding anything electrical, and that i should speak to my chosen installer.



So, i guess the new question is, if you could design a system to make the most of export income, with 45kwh batteries, what would you do, and what kit.

Roof solar is 2 strings 1.2kwh facing NW, 1.6kwh facing SE.
1 string Gable end wall. SSW, with space for 6 large 500w panels
1 possible string on fence facing SSW. Dependant on if the new neighbours (house for sale) decide to put anything in the way or not.
1 string on shed roof, yet to be built.
1 single large panel can go on the power shed (possible micro Inverter)
1 string of Random panels for garden/pergola flower beds etc. Either optimised or micro inverters.

The length of the posts needed to get over my info (i waffle alot)
Is why ive sat and stewed.
I had hoped a sparky would make suggestions after seeing the site etc whilst quoting. Alas, nothing.

I kniw what i want to do, just not what i want.
Like a typical woman, i want it all

Pic of the house showing the gable wall and fence i want to adorn with solar. If the new neighbours decide they want an enclosed garden the solar fence is kyboshed.

In a sentence? Hoymiles microinverters and forgetting export, plus a decent victron dc charger controller for the 3kW 6 panel string. Forget installers you can do all that yourself except connecting the batteries to the grid via an AC inverter.

I've been talking to a pal as he fancies some solar. Pretty sure when he drops the first hammer it will be on a Hoymiles HMS 2000 micro and 4 of close to 600W panels.

The beauty of if is (and for anyone else looking in), is that you get a self installed 2kW system to learn on, it's on your timeline and budget so no over runs on time or cost. Plus you can get the hang of it, see if its really for you and then install something bigger with a grid connection and the 2kW diy system will still be generating throughout and beyond.