Nonlinear

Thanks @Solaris. I do have the balance wires, which I'm hoping helps a little. I wired them as suggested in the BMV manual. I'm using a BMV702 and it has started to alarm on the voltage difference alarm, but luckily not often. Still, I'm a little worried but not too surprised, especially since my Axperts are not known to be very kind to batteries in general. I'm hoping to get a few more months out of them and then probably switching to the PylonTechs. If only there was an inverter that is reputable, well-designed and that can be paralleled to provide the power that my Axperts give.

Hi All, I was hoping someone would have some advice on the best way to rotate lead acid batteries. I have a lead acid battery bank consisting of 8 x 12VDC (nominal) connected in a 2x4 bank. They have been in service for more than a year now and after measuring individual cells recently I noticed they are not as even as they should be. I am thinking of taking the first and last cells in a bank and making them third and second respectively and making the original third cell the first and the original second cell the last. Any opinions? Am I over-thinking this?

@Coulomb I was wondering if your 73.00e firmware will also help with respect to DOD on older batteries specifically with the "KettleComp". It should prevent unnecessary switching when DOD is not as deep as the Axpert thinks. I think though that the 73.00e is not applicable to these smaller inverters.

My understanding is that centurionsolar and ICC have parted ways. You may instead want to go to the source and contact @Manie or [email protected].

At some point in the past year or so there was some conversation with respect to solar certification. Unfortunately my memory and Googlefu lets me down, and I don't recall if it was here or elsewhere. Nevertheless, there was some talk that in the future any solar installation would require a sign-off from an electrical CoC perspective (by a competent electrician) and a sign-off from a "solar certifier" for the solar PV side. I'm hoping that possibly @The Terrible Triplett or possibly @plonkster may recall. This may only have been relevant for CoCT though.

Well I can finally say that my axperts are now in parallel and operating as well as can be expected. I have one question though that @Chris Hobson is probably best placed to answer because I think our setups are quite similar. How do you wire the contactor to ensure that you bond earth to neutral on both units irrespective if one or both units are on line. I have a three pole contactor and I take the neutral output from each of the units into the line side and bridged earth on the load side but do you wire then n/o contact from live out through common of each inverter in parallel to the contractor coil?

I like that idea. I think I will do something similar but due to layout constraints might separate my positive and negative busbars. One question though: are the individual battery wires coming in with the square trunking? Are the leads for the BMV also taken in with the trunking or do you do midpoint measurements in some other way (if at all)?

So far I've gone with 35mm2 on a similar battery bank and inverter. For volt drop reasons but also for pragmatic reasons: anything above 35mm2 becomes a real pain to terminate. Both finding the right termination and the actual task of clamping/crimping (not to mention the cost of tooling). I'd like to hear from others who have used anything above 35mm2 what their termination methods are.

To be honest that was a little bit of future proofing that probably was not necessary. My intention has always been to use the Axpert as a learning curve and finally settle for a more long term (dare I say) higher quality inverter. It seems from what I've seen over the last while that the majority of inverters and panels are moving towards higher voltage/lower current and thus thicker wire is not required but just in case I do ever need to drop my voltages and up my current then all I need to do is swap out the fuses and possibly breakers and I should be good to go.

Hi Guys, Sorry about the delay, things got a little hectic in the last day or two. See below for some pictures. Unfortunately due to the addition of the new equipment the trunking covers are off, conduit removed and boxes are open. I'm not sure how to "inline" pictures so hopefully these are OK.

Hi Everyone, Although I've been registered and lurking quite some time, I thought I should at least introduce myself before posting too much more: I'm new to PV in general but have had some exposure to other forms of power generation. Currently we (our household) have a single array attached to an Axpert 5kVA PF0.8 unit with 400Ah of storage in lead acid cells. Although the system operates reasonably well it has some quirks. In the last few weeks we've begun the process of adding a second array and intend to attach this to a second Axpert in parallel (as per one or two of my other posts). Other than the inverter and the solar panels everything else in our system has been designed by me and built in-house (so to speak) and we've put all the bits and pieces together as best as we can. It's been a long road so far, we've worked many long hours and learned some expensive lessons but can proudly say we did it all ourselves. Although we have an operating system I regard myself as a total newb and thus am keen to learn from the many experienced members. Cheers. Nonlinear.

I actually do, I've really struggled with browsers in the last while. When they broke all the really good add-ons in Firefox I moved to Chrome but had some issues. Now I think Chromium is about the best solution because it is relatively no-frills and still allows the majority of add-ons that work in Chrome and (I think) it is slightly less offensive in terms of tracking and privacy.

I also did not know how to do that @Chris Hobson and then realised that it might be a browser thing because now it worked (I'm on Chromium).

Excellent thanks guys.

Thank you, Plonkster and Chris (I wish I knew how to do that blue link thingy), I agree wholeheartedly, earthing is not for lightning strikes but rather to protect people from accidental contact. Also, as Plonkster said, in my case (for reasons unknown) the neutrals are bonded throughout, which is fine until someone opens the main switch while PV is on. Our main switch has never been tripped and only once or twice switched, but there is a first time for everything. My problem is (as already pointed out) if I now bond earth to neutral after the inverter (as suggested) I create a second bond which is a no-no according to SANS. So the only solution (that I can see) is to figure out how to disconnect the neutrals when in "off-grid" mode and to simultaneously bond the earth and neutral.

Well this is exactly my setup, although unintentionally due to (I think) the Axpert. In my case the neutral is bonded to the grid side, I've checked both during grid bypass and during PV generation. Considering that my neutral is bonded at the incoming DB to earth (I checked) effectively this means my neutral is always bonded to earth. I have significant surge protection I think: an SPD on the incomer, an SPD on the feed before the inverters and a DC SPD on each array combiner box. I also have an E/L as per the SANS requirement (and diagram in the 2018 rev) and I have a DC GFP per array. However, all of this is useless if I've gotten the earthing and bonding wrong. In my case I have a pretty old Axpert so I think it means I would need to put in a separate contactor if I want to explicitly bond earth to neutral on the outgoing side of the Axpert. Also, if the latter is the best approach I would need to install a separate earth spike in a good location which is not so easy in my location (but not impossible). In general I've tried to follow SANS to the letter and used the NEC guidelines where they are more stringent.

Thanks Chris, and others. Much appreciated, now I have some peace of mind on both my breaker problems and firmware worries. Now all I need is to buckle down and get the rest of the install done. I want to re-read the posts here and elsewhere (and on MyBB, 4x4 and Aeva) with respect to earthing and neutral. I have measured continuity across my neutral bars while the inverter is on solar and I'm not sure I understand how that can be. Does the Axpert bridge incoming neutral and outgoing neutral? Anyway, before I make any more bold statements I want to review this issue and possibly start a new thread.

Ditto. I'm a very nervous solar explorer so I have fuses on positive & negative per string, positive & negative per array (combined string) and DC breakers per string and per array. Belts and braces perhaps but I'd hate to set my house on fire. On second reading of the Gewiss datasheet though I see they do provide a rating for 2 in series so that may be a solution in my case because (according to the datasheet) that takes the rating to 100VDC which is sufficient in my case.

Unlikely! I think newb versus supreme master says it all. I trawled the Gewiss site a bit and downloaded the MT60 datasheet as a start and they are indeed rated at 50VDC. That solves my problem on the DC output side but unfortunately not on the PV side, voltages are well above 50VDC in that case. I will do a bit more trawling though... Thanks. Much appreciated.

Thank you. I am relieved, I don't want to muck about with this, things are already complex. As a side question (if it is OK), I really like that picture of your new DB, and will be looking into some of the distribution blocks too, what is the ACDC code on those? Also, the Gewiss breakers, are they DC rated? The ZAR/USD exchange rate is killing me and I'm hoping to find an alternative to the Carlings I have now?

Thank you sir! I must have misread your posts on Aeva and here. I was under the impression that for older PF0.8 inverters like mine the highest I could go would be 72.40 but I stand corrected.

Hi Chris et al, I'm new here and I hope this is not regarded as a thread hijack. I'm intending expanding my setup and it is very similar (if not identical) to your setup, in that I also have an RCT 5kVA/4kW (currently running) and plan on putting it in parallel with a Mecer 5kW/5kVA (not yet running). I have two very general questions thus: 1. Have you found that the RCT and Mecer are able to operate in parallel successfully, if so, which firmware versions did you use to allow parallel operation. From my reading here it seems (in my case) both would need to be running 72.40. 2. Is the Mecer an actual Voltronic inverter or only a clone. My concern is that I may not be able to get the firmware versions updated to allow parallel operation if it is a clone. Any help, advice or further information on your particular installation would be much appreciated. Thank you.