Kibim

Really Good info, thank you!

Thanks for the answers here, and i've done some of my own digging too. The basics of it are as follows : The axpert has an 'ideal' PV input voltage of +- 370v, so my current mid 200v is just tickling it. I could add 4 more panels to get to it's ideal voltage range on the same string. This is where is starts getting interesting however, and from a bit of research into how mppts work, it's NOT going to yield suitable results to connect 2 strings in parallel where the strings aren't identical. IE , same panels, same orientation, etc. So, it's time for a second inverter, or a dual MPPT inverter if i want to setup east and west facing strings. And now the tricky part ... what to buy, and how to pay for it. but that's a different problem

To add, it's the Open Circuit voltage that bothers me the most, So in full sun, with little to no load. The panels are close in voltage, lets average it to 50vdc * 12 panels = 600vdc, which is way too much for the mppt. Obviously in parallel its +-300vdc OC, but double the amps, and will the voltage difference between old and new be an issue. Or do I wire 'em up 3 old, 3 new in series, with the 2 strings paralled into the MPPT. Again, it's unlikely i'll ever hit 12 panels max efficiency because of the array directions. I guess i'm asking, which is the better way, because there's at least ways of doing this, 5 if get creative, and many more the longer i think about it.

Hi, Same Axpert, FCS-MKS III 5KW 5kw mppt single string Panels : JASolar Mono PERC Half-Cell MBB LR MC4 old = 540w, new 565w - same brand, same series I'd have to run the 2 strings in parallel as in series i'd exceed the max volage of inverter, @ 450v. I currently run around 220-240V depending on the efficiency. But i guess neither string would be pushing full efficiency, so it could be that series might just work. Or I only add 5 panels rather than 6. The other option would be to get a second inverter, then run the inverters in parallel. (there's a redundancy in that too) but that's a whole bunch new wiring and will probably cost R15k more over the R13k +- for the 6 new panels. With ONLY the benefit of redundancy. (and lazy maths .... )

Why have one, when for the same price you can have 2? reliability. One fails in a 2 battery setup, you can still limp along. 1 battery, 1 failure and you're dead in the water.

@Rory, If it makes your decision any easier, i've been off-grid with 6 panels and a 5kva inverter with 2x 5kwh batteries for a few years now. Gas water heating and cooking. We only struggle after day 3 of thick cloud cover, and i have a small 2kva inverter gennie to keep the essentials running (which i've only started twice in 2 years...) Only recently looking to upgrade to 12 panels which will of course help those cloudy days anyway, and to assist running the aircons in the hot lowveld afternoons.

Hi all. I have a setup which i put in for my off grid holiday house a few years ago, 6x 540w panels and a 5kva Axpert King III inverter. It runs the house nicely. But we've now moved here permanently and i'm feeling the pinch a little running work servers/laptops/aircons etc a lot longer and harder than before. My current array of 6 panels faces north east, and I want to add another 6 panels to face northwest/west. The aircons work hardest from 3pm to 5pm and its when i start loosing efficiency on the solar. My JHB house as 2 x 4 panel arrays on an east/west pitch with an Axpert 7kva dual mppt, so wiring that up was easy. Can I parallel the 2 arrays (6 panels each, same manf/series panels, although a few years newer) into the existing setup? The current(I) would obviously get close to double at midday, but i have lots of headroom on the inverter still, my only concern is the voltage(v) difference between the 2 arrays at the different times of day in a parallel config. IS this an issue?

Yup, the batteries seem to talk to eachother just fine, but not to the inverter. I suspect it's a protocol setting on the battery, as i've really tried everything. As Mark says, the only way into the battery is with a RS232 to usb device (and no doubt a special cable) with the Svolt software on a PC. I really don't get why we can't do communications via IP or USB. Serial is so last century. But i guess it's kinda bulletproof once it's up and running.

Ya, typo/me being a dumbass. MKS III It is supposed to have a Pylontech compatible protocol, as well as pin-out. But it has a host of options, and inverter options too, so i've ordered a USB to serial(232) to access the battery config and make sure they're setup properly, and a USB-Serial (485) so i can see if i'm getting sensical data out of the RS485 port.

Hi All, long time reader, first time poster. I have an Axpert King Mk3 5kw inverter and recently upgraded my 4x AGM batteries to 2x Svolt 105AH Lithium. Batteries installed, in parallel using the purchased parallel cables, and connected together with the supplied RJ45 cable on RS485B terminal. RS485A is for the inverter communication, and that has a special pin-out, with 8 to 3, 7 to 5. I've crimped so many cables now i can't see straight, tested them with a meter to check pinout etc, and all other info i can find says i'm making the cable correctly. But the Axpert doesn't think so, and when i change over to pylon type battery, it gives me a communication error after 3 min. (fairly standard delay i believe) So what have I missed, because it's probably something stupid.