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Nonlinear

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  1. I have a set of Mecer Axperts in parallel and am slowly migrating to the blue side. I still retain a keen interest in the Axperts because I maintain they are acceptable for most people who run them within their capabilities. Also, having lived with them for a number of years I have experienced the highs and the lows of owning Axperts.
  2. I am quite aware of that, I was hoping to use that as a gentle introduction to the topic.
  3. It was a struggle (to put it mildly). For bonus points I can confirm I used the regulation SANS cable too which was even harder to do. Correct. The problem though is small differences can have a large impact when resistance is already low. So, for example, with a very large (say 16mm2) cable the resistance on each could be very low, about 0.02Ohm. Now a small difference due to terminations could make the one cable 0.025 and the other 0.015. Now you can see that the resistance differential is potentially a problem. If you use smaller cable (say 6mm2, which would still be legal) then the nominal resistance would be about 0.1Ohm, now a small change in due to terminations would only change that from 0.105 and 0.095. So now a small resistance change is not a problem. On my two inverters I have noticed that despite my best effort at getting the cable lengths exactly the same, and terminating exactly the same way, the one inverter always runs with more load. There may be other reasons for this that I am unaware of. Indeed it is.
  4. Having read through this with some interest I would say that your best bet may actually be Victron Quattro units 6x10kW. Coupled with each would be 250/100 MPPTs and each with about 40kWh of storage. The reason for going even larger than the 8kW would be the fact that air-conditioners are particularly unpleasant loads at start-up. Additionally the Quattro gives you the option of connecting generating power as a secondary AC input and they have the option of running PV on both the AC and DC side which allows you to connect some of the panels (via a Fronius) on the AC side thus sparing you the need to couple all PV on the DC side. The Victron website has a few reference projects using Quattro units at roughly this scale. Disclaimer: I do not work for Victron and don't run them in my setup.
  5. I'm not sure if it is of any benefit here: For a few years I ran two PF0.8 5kVA inverters in parallel until a lightning strike right outside toasted their communications boards. They were replaced by new Mecer units that are PF1.0 5kVA. I can confirm that the newer units are significantly louder than the older units. As Coulomb puts it, objectionably loud. I can also confirm they are always loud even though the temperature is never high and solar production is always well within the nameplate capability of the units. The WAF on these units dropped from 10 to 1 as a result of the noise.
  6. Interesting topic. I have something similar. Two parallel inverters. Breaker on the supply side of each and breaker on the output side of each. Breakers on the supply side are 40A each and on the output side are 50A each. Single pole (common neutral) on the supply and double pole on the output. I currently have one isolated and removed (long story) and the other is operating seemingly well. I tried to match wire lengths on the input and on the output. My mistake: I think I oversized the wires on the output because I had a future upgrade in mind. My wire size is 16mm2. I'm fairly convinced that even though I attempted to match the wires as best as I could I think with wires that size small differences can make a big difference. Opinions? I can say that in most other respects the system seems to work well and has worked well for quite a long time (barring a lightning strike).
  7. Hi, thanks for the quick response, sent you a WA.
  8. Ouch. OK, that is on the other side of the country. Let me see what other options I have. Does it have a parallel comms kit?
  9. Thanks @P1000 I'm happy to report the FTDI converter works. Results of dmesg [160585.535658] usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [160585.535666] usb 1-1.4: Product: US232R [160585.535672] usb 1-1.4: Manufacturer: FTDI [160585.535679] usb 1-1.4: SerialNumber: FT4WLQTJ [160585.571538] usbcore: registered new interface driver ftdi_sio [160585.571583] usbserial: USB Serial support registered for FTDI USB Serial Device [160585.571745] ftdi_sio 1-1.4:1.0: FTDI USB Serial Device converter detected [160585.571823] usb 1-1.4: Detected FT232RL [160585.574534] usb 1-1.4: FTDI USB Serial Device converter now attached to ttyUSB1 No reboot required. Next I'll try to make up a little breadboard with the chip you suggest above and play around to see if I can get it to work.
  10. I saw the FTDI stuff on RS (because I buy there anyway for business reasons) but I was not sure if it would work. I am almost at the point where I would say cost is a minor/secondary issue simply due to the immense inconvenience/time/money involved when a surge damages the communications on some of your kit. It has taken months of haggling with the bank and quite a large amount of my own money to get my solar system back online. I'll have another look at the FTDI and I will also read up on the ADuM (is that Analog Devices or just a coincidence?). Thanks for taking the time to post.
  11. Hi Everyone, Can anyone provide me with suggestions for reputable RS232/USB converters. Preferably I would like recommendations for converters using the PL2303 chipset (because I know it is well supported under both Linux and Windows). I would also like to hear members opinions on isolation or opto-isolation on these converters to ensure that surges and other nasty effects are not sent through to the expensive equipment connected on the RS232 side. As you can probably guess I lost some equipment due to a surge transmitted on the converter to batteries and inverters which fried the comms on these devices. As a bonus, it would very much be appreciated if these were obtainable in South Africa.
  12. Hi Fredi, I had exactly the same RCT Axpert. Upgrading to the firmware maintained by @Coulomb (and Weber and others) at this location https://forums.aeva.asn.au/viewtopic.php?p=53691#p53691 (actually that link is to the first post which is a must read to give you guidelines on the entire process). It made a huge difference to my system performance.
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