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CDL

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Everything posted by CDL

  1. I am in Johannesburg and my roof slopes about 30 degrees I guess. Quite clearly, the incidence angle of light is not optimal. But I can't understand why I was getting 2.5 kW from each array a month back and now I am down to a kilowatt. Certainly, as we move deeper into winter I would expect less power output but not as dramatic a drop as I have seen. To my mind, there only two possibilities: (a) there is a problem with the panels or the installation of the panels or (b) I do not correctly understand what the incoming kilowatt reading correctly means. I say the possibility of (b) because I read elsewhere on the forum that the Axpert reads the incoming kilowatt on the battery side and not on the incoming PV site. That strikes me as a little strange but if it is correct, it may mean that I am not correctly understanding the data that I am seeing. But I think that the suggestion that I should get a clamp meter and actually measure on the cables is a good one. It is likely the only way to be sure what is going on. Now I need to find myself a clamp meter which is adequate for the job without being totally over the top in terms of cost…
  2. Thank you for replying. Much appreciated. Each string comes through a DC DB which has a separate isolater switch and a replaceable fuse for each incoming array. The fuses are 32Amp fuses and the incoming voltage is 230V per the inverter readings. I do not have a DC camp meter but could easily purchase one. It's probably a good idea for me to do that and then get up on the roof and check the output of the panels by measuring on the various cables.
  3. Hi guys, I have an array of 28 Canadian Solar 335W panels (thus a nominal total output of 9 kW or thereabouts). They are arranged in an east-west setup on a residential roof. 14 panels face West and 14 panels face East. These panels are mated to two Axpert inverters, which in turn are mated to two 10.2 kW 2nd life batteries. When the installation was first put in, we had a problem with the inverters throwing up an error 86. This turned out to be the batteries not having been correctly wired (each inverter was seeing its own battery array as opposed to the two inverters together seeing a single battery array). Thanks to the advice from Youda this issue has been corrected and resolved. The incoming power on the inverters is set to the maximum of 80A. When we first installed the panels (towards the end of April), we were commonly getting 5 kW during the middle of the day (reading the incoming power on both inverters together and taking them collectively) on a clear sunny day from the 28 panels. Sometimes it would even rise towards 6 kW. At the moment I never seem get more than 3 kW and more commonly 2 kW under optimal conditions between the two inverters together. That said, I was reading these numbers yesterday at a time when the batteries were full or very nearly full. I climbed up on the roof just inspect the state of the panels and they are really quite clean, so I don't think that that is much of a factor in context. I understand from other posts on this forum that the inverters read the power on the battery side, not on the PV side, so now I am wondering whether I am reading the inverters correctly or incorrectly and whether there is a problem with the panels or whether there is a problem with the way the user understands the data…
  4. Thank you. I found this too yesterday: https://www.thesunpays.co.za/ManualParallel-installation-MKS-4Kva and 5kva.pdf See item 5 which speaks directly to the issue and reads: 5. Battery Connection WARNING! Be sure that all inverters will share the same sets of batteries. Otherwise, the inverters will transfer to fault mode. WARNING: Be sure the length of all battery cables is the same. Otherwise, there will be voltage difference between inverter and battery to cause parallel inverters not working. Follow below chart to connect batteries. All battery cables are connected from inverters to batteries via the same BUS bar. I opened the trunking up and couldn't find a busbar. Unless its behind the DC DB, which seems unlikely.
  5. Quite correct. I only know that 14 panels serve one inverter.
  6. Thank you Youda. It seems to be quite clear just from the LCD displays that each inverter is seeing a separate battery array. I would have to open trunking to trace the wiring.
  7. Hi guys, I have an ongoing problem with a pair of Axpert inverters that I have had installed and I am hoping that someone can point me in the right direction for a solution. The installation was done by an installer but they seem to be as stumped by the problem as anybody else is. The basic details of the installation are as follows: 28 335w Canadian Solar panels in two strings of 14 each. 2x Axpert inverters set up in a "master-slave" relationship. Two x 10.2 kW Revov second life batteries, each with its own BMS. The problem seems to have a pattern which is as follows: Typically the batteries are either fully charged or very close to full charge. There will be little to no load on the system. it only occurs during the day when the panels are pushing out a great deal of power (let us say in the order of 40 A to 43 A per inverter). A voltage discrepancy arises between the inverters. one of them will typically show 54 point something V and the other one as much as 64 point something V. The slave inverter will then default to an error 83 and throw up a red light. If I switch on something that creates a load, then the voltage drops and the two inverters start working properly again. Take the load away and the problem pops up again. If one keeps the system without load, what will also often happen is that the error 83 will pop up as the voltage rises above 64 V and then as the voltage drops again, the error will go away. This site will continue repeating itself either until load is placed on the system or panel output reduces towards the end of the day as the sunlight fades. Another problem that we have had recently – and I do not know whether this is related – is that when we ran the batteries down overnight (they are set to cut over to utility at 48 V), the one unit showed voltage as low as 34 point something and the BMS shutdown altogether – no lights. The other battery was showing something more than 51 V and the BMS was still working fine. The battery installer has since been across and fitted a comms cable between the two BMS units. I have not yet had an opportunity to ascertain whether the foregoing problem has been fully resolved or not. But I mentioning it for the sake of completeness. Does anybody have any ideas? All input much appreciated.
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