Kalahari Meerkat

Hi @AlanPS67 , no experience with this lot, but I'd imagine you should be able to set things up, to mainly run off battery+solar when the tariff is high and then, run off the grid when the sun doesn't shine, depending on the SoC of the battery and even charge the batteries, when the tariff is low and the batteries need som charge returned to them...

it should make a difference, how noticeable, is tough to predict, if there is no partial shading on either of the strings, when they should be producing energy, it should be worthwhile, I'd say the inverter should throttle the power back to what it is able to consume/charge the batteries the more important one is the strings Voc, which should be ok, I think, just a hair under 50Voc per panel * 7 = 350Voc per string, which, I believe, the Sunsynk would be ok with, maybe double check this, I don't have a Sunsynk here anymore...

Ideally you would want to take temperature readings in the manifold and compare them to the temperature in the HWC (hot water cylinder), if the manifold temperature, is more than, say 4 degrees Celcius higher, then you'd want to run the pump, if its is 4 degC or less, you probably shouldn't...

I seriously doubt that these were LFP. NMC type Lithium Ion, sure... As for the 1st video in this thread, I saw lots of 18650 cells in the video, who has a LiFePO4 battery made up of 18650 Cells? Will Prowse has a video addressing the LiFePO4 issue and it is supposedly a serious health hazard if the LiFePO4's should vent, however, the amount of failures of the LiFePO4 cells. or rather the lack of failures, indicates to me at least, that you should be aware of the possible hazard, but don't panic, if you have treated your cells well, did not drop them, did not over charge or discharge them, then the likelyhood of things hitting the fan is so low, that you should not over-sensationalise the very few failures that do occur, rather investigate why, if possible, the failure occurred, the 1st video in this thread, the battery with loads of 18650 cells, how was this put together by the manufacturer? If they have loads of parallel cells, which they presumably had, was each cell fused individually? etc. I think for us homebrewers, 304 or 314Ah cells in 16S format with a decent BMS, we probably should be aware, but don't have to be unrealistically concerned about gassing, as long as we treat our batteries well. I don't come near the 3.6V mark, heck I charge up to 55.2V (/16=3.450V per cell) and the lowest I've seen to far is 51.33V (/16=3.208V per cell), with maximum cell delta of 0.034V aka 34mV on my worst 304Ah battery in the last 33 days, the rest of them 15mV, 13mV and 12mV. Based on this, I believe that my cells won't vent and will carry on operating for many years into the future. As it is, my batteries/inverters/MPPTs are all in the garage which is very well ventilated, chances of hydrogen or other gas accumulating is pretty much non-existant. If you have LiFePO4 batteries, obviously they probably should not be in your house, but the NMC type Lithium Ion batteries are the ones, I would be a lot more worried about.

Quite right, sorry, didn't pay enough attention, read Deye, when it actually said Dyness... I can't say for certain, but I'm pretty sure one of the protocols supported by the Sunsynk should match with Dyness. again. someone who actually knows the Dyness batteries should be able to confirm... personally, @JTK, I recommend homebrewing batteries, more cost effective and you actually have a better idea what makes up your battery....

Yes it has two separate MPPTs Yes, within limits of the MPPT, can't remember, but possibly around 20A Isc and 400Voc, check the manual/specifications for that inverter. Maybe, but I'd check the Voc or the existing 7 and make 100% certain there is room for expansion, but personally, I wouldn't mess with the existing string, I assume it works and you already have nearly 4kWp solar on that MPPT, fill up the other one rather. Yes, same or more current, but I'd suggest you leave the string as it is, rather... should be fine as long as the Isc and Voc values of the string fall withing the MPPTs specifications... I would think not, same manufacturer, just Sunsynk is a different label/Deye rebranded and sold under the Sunsynk name. But others may know more, as it is, I doubt that Sunsynk or Deye actually manufacture batteries, so yet again some other manufacurers items being rebranded...

Discussed here. And manufacturer test info here.

I can't recall, but if you are getting an IP address when joining the WiFi AP of the datalogger, it should give you its IP address as your default GW and it may not be 10.10.10.1, but maybe even 10.10.10.10... just check this out, if you can join the network, I'd assume the dongle is functional... but obviously the device/machine joining the WiFi network is the one that you have to check on the IP address and gateway for the WiFi interface and also the one you have to run the web browser on to configure the datalogger...

don't you have to join and connect to the dataloggers WiFi network, in order to be able to set it up/access it initially?

Ok, and now we shunt the output into a appropriately sized resistor and we measure Tension, not current, which we can translate back to the original current flowing in the single loop of the transformer, right?

The CT is exactly what its real name says... a Current Transformer... basically it is a coil through which you run another single coil (just your live or neutral wire through the center of the CT), this then forms a transformer, where the current running through the single winding is providing a magnetic field to the multiple windings of the CT's coil, this, with the single winding becomes a actual transformer, but really not much power can flow, since probably a few thousand windings vs one, while not transfer much, but will provide some mV's of measurable Voltage which can be used to calculate the current flowing. The problem with most inverters is that if a high powered consumer device which is being powered by the inverter is switched off, the inverter needs to get rid of some energy fast, so as not to let the Voltage on its output rise rapidly and usually the easiest way is to feed the power to the input end... and thus the grid... at least that's the way it seems to me...

@Meerkat roll your own, would be my suggestion, that's what I did, 4 X JK BMS' here and each of those has 16 X 300-odd Ah EVE cells connected and running our home totally off grid near Grootdrink, I'd be wary of 2nd hand batteries and even new ones, what BMS do they use etc? Personally I reckon that most BMS' out there are not something I'd not be happy with, the JK BMS' are the 1st ones that had active balancers of up to 2A, where initially most BMS would balance at 100mA or less, by running excess energy into a resistor and heating up the place :-)

Did nobody read what @DAVID-EC wrote? Either another 5kW in parallel or a single 8 or 10kW, The doubling up on everything was somewhat off topic....

Ok, lots of off-topic postings, let me muddy the waters waters by throwing in my 5 zim-cents worth... If all you need is more kW power from your inverter, but not more solar production options, then two 5kWatters are fine, but... looking into the future and maybe even now, where you may want to add more solar panels to produce more power, the 5kWatters are a bad idea, they are limiting the current on the PV inputs such, that quite a few panels that are available these days won't foot the bill and you may struggle to find panels that will work well with the Sunsynk/Deye 5kW inverters. The 8kWatters are a better option and looking at Solis should not be off the table either.

That should work fine, I have not tried it myself... Deye + extra MPPT, but there should be no reason for this lot not to co-exist, the only possible problem may be that you might not be able to use battery comms between inverter and battery, but may have to run Voltage based...

Not a plumber, but I'd think that you would not want another HWC, but just the manifold, evacuated glass tubes and pump, to add this to you existing HWC, else how would you mix the two HWCs together, but unless you require more volume of water, it would make sense to me, to just add the extra heating capacity with its circulation pump, assuming your existing HWC has the option to have the extra out/inlet connected to the evacuated glass tube manifold...

I can't recall exactly, but there is a setting which determines what the minimum SoC would have to be for the inverter to supply power, when off-grid and at 13% as in your attached photo, I'd say its too low, maybe look for the setting that ties in with this... I used to run a Sunsynk 5kW, without grid, period and yes, pain in the A, when it resets or has to be switched off and on again, it can take 2 or 3 minutes before it starts generating AC instead of getting to it in a hurry, glad I'm off the all-in-one HF inverter...

Hardly, but ok, on my side, running open ended, the voltages are set on the MPPTs, since there is no charging from the inverters... if I run closed loop the the battery aggregator on the Venus on a Raspberry Pi, would be the responsible party for bulk Voltage etc.

Lets hope it stays like that... I am running open loop. since the inverter would panic and switch off, when one cell goes over voltage at the top end of the charging cycle in closed loop. Now no issues... I assume in your setup the BMS determines the charge voltage etc?

That has been my leaning as well, if one MPPT packs up it doesn't affect the others or the inverter etc. so a more redundant setup, sure, more individual components, but the same as with batteries, you have similar to my setup some home-brew EVE 300-odd Ah based batteries, if one goes south, BMS or one or more cells/whatever, you are not off, but inconvenienced and you can sort it out, without being without electricity...

I did not go the MC4 route, since that would require more plugs yet again... since the wiring comes from a circuit breaker, which does not use the MC4 connectors, I have stripped wire ends (without bootlace ferrules) going to the MPPTs and on the CBs end. Ideally we'd need to check your panels' specs, I just thumbsucked the number to make the point that all eggs in one basket is not the correct option, in my opinion. If these are your panels, then 49.62Voc seems to be the number, call it 50V, so a maximum of 5 panels in series on the 250/whatever MPPT would be ok, I'd think. Now if you did 5S2P, then you'd come close to maxing out the 250/100, so one of those and another smaller one for the remaining panels or get some more panels and fill up another 250/100 for 10kWp MPPT/solar power...

yes, well, there is no reason to throw everything at one MPPT... you could for instance consider doing 3 MPPT's, 2 X 250/100's (6S1P panels each, assuming the Voc fits) and one to suit the remaining 2 panels, there is more than one road that lead to Rome... I also was of a similar feeling, specially since Victron was very expensive back in 2020/2021, but since their pricing has come down quite a bit and unlike your all in one outer-Mongolian units, are fairly EMI/RFI quiet, as opposed a lot of the all-in-ones/high frequency inverters. Looking at just one MPPT does not make sense... lightning strike and the MPPT is gone... no panels will produce power, whereas if your panels are slightly spread out and running on 2 or more MPPTs, then you may at least still have some solar power being produced, if weather has struck... Just because your 14 panels in a single string may fit the 450/200 (not sure, maybe its 7S2P), does not mean that this is the correct way to implement the solar power production side... Here, FYI, I was running a 5k SunSynk, now I have 3 X Multiplus II 3000VA's in parallel and 2 X 250/100 MPPT's + 1 X 250/85 MPPT and a bunch of batteries... off Eksdom's infrastructure, of course.

maybe its for a box of 12 :-) In addition.... maybe these may be more realistic in terms of pricing, just finding fuse holders that are rated at 150+A...

Going overboard on earthing is always considered to be a good thing, if you have the space and possibility, putting up some lightning rods, somewhat away from you panels and not causing shadows, might be worthwhile considering... Maybe post some photos of the panels setup as it exists, if you can. I still think the best option to prevent major damage from lightning strikes is to implement a system that has multiple automated disconnect points and is driven by a field mill, which pretty much will show just before a strike that this is about to occur...

String 1 - Could be a panel, I assume none are shaded... String 2 - could be a poor contact on one or more mc4 connections String 3 - not sure, but see this thread... String 4 - same as String 3, presumably an earth fault on those two I'm spitballing here, I have a smaller Deye, but this is still sealed in its box...