HermoT

Wise advice thanks. Was my conclusion as well. Appreciate it!

I am just challenging what happened in terms of the original installation, and why it was changed and whether it was changed in the best way possible to make optimal use of an expensive investment. My feeling is that my expectations were not managed correctly, and the installer even apologised and confessed it was a mistake on his side. So I am rightfully sceptical and just learning more about the possibilities of what could have been done / not done. In his defense, he acted quick to correct the risky situation of the volts running too high. From what I learnt here, I should be better off now having an extra string facing west and the rest running at safer voltages. My interest now is just to have peace of mind that I can still later optimize and upgrade if the need arises.

I have the SG02

Thanks for explaining it to me!

My understanding was that because the voc is lower, the panels are not as efficient as they would be at higher voc, so is the 11.2kwp on the 3 mppts still possible even when spread out through the day?

The same argument my installer has. I agree somewhat with this, but I had other plans to increase the load over time by adding aircons and use more things that I never could before because the grid is too expensive for those. So my priorities are future expansion of my load, without wanting to pay again for reconfiguration of strings etc.

Oh my….this is interesting. I had the gut feeling that my investment was kind of dumbed down a bit. I got the impression from him that 7 was the max he would go per string, because apparently he felt 8 was still too close to the MPPT max 🤷🏻‍♂️ So if that was true, it means I could only upgrade with a single panel to make the 6 panel string equal to the other 7 panel strings. This just didn’t feel right to me. Learning about the parallel options I am already feeling much better and less despondent. I was worried that with the expensive investment I made, I still didn’t have much room for future upgrades. I will check in the SunSynk manual where I can view the MPPT configuration.

Thank you! I had no clue about the option of parallel strings until you mentioned it. He never mentioned it to me, and I would be surprized if he didn’t know about it either. Could there be any reason he may have avoided a parallel layout (if he was aware of the possibility)? Like some other risks or more difficult setup or anything like that?

Thanks @abd7 and @Denns . Sounds like it is normal and a wise procedure to stay within MPPT limits. Not knowing about these safe limits before the initial install, I guess I was given the wrong impression of how the system should perform (actually overperformed). Think one can compare it to overclocking a CPU, right? So the problem is that the initial install became the benchmark in my mind and I kept comparing the second layout with the initial layout. But I guess I am now slowly finding my peace!

The panels on the quote: Trina 555w Mono Solar Panel (TSM-DE18-555w) Silver Frame According to this website: https://www.getoffgrid.co.za/product/trina-solar-555w-tsm-de18-tallmax-monocrystalline-panel/ there are two Voc values: STC: Voc 50V NOCT: Voc 47.1V Not sure what STC vs NOCT is? Will this help?

Hi, I recently had a brand new system installed with 12 kW SunSynk inverter and 20 * 555W panels (10 per string, one facing east and the other north). Initially the 3rd string was not used. The technician informed me soon after installation that the voltage was operating too close to the inverter’s max of 500V. We could see it climb to 480V once batteries were fully charged. When there was high load, the voltage dropped to under 430V According to him and also to ChatGPT, the MPPT safe range is between 130V-425V. He then disconnected 1 panel per string until a later date to rewire and rearange things. With 9 panels per string, the voltage would climb to approximately 433V under low load and drop to 380V under high load, which was safer than the 10 panels per string. Since the MPPT max is 425V, 9 panels were still too many according to the technician. Eventually my 20 panels were reorganized and split among the three strings as follows: 7 east/ 7 north / 6 west. Today I found to my biggest disappointment that the panels do not give as much power as it did before with only the 2 strings. On initial installation it could deliver almost 8kW under high load. Today it could at max only provide 5.7kW. The battery then had to jump in and help out, which wasn’t necessary with the initial layout. The initial layout had the two strings on east and north facing roofs. 10 each. The new layout has 7 east, 7 north and 6 west. That means that after 13:20-14:10 when my observations were made, the sun was in the north-west location. According to my logic, I now have 13 panels (7 north + 6 west) facing north-west for maximum absorbtion of sunlight in afternoon as opposed to only the 10 north from the initial layout ( ignoring the east panels for now 10 vs 7). I would have expected that to mitigate the drop in the voltage to some effect? To me it feels like a severe drop in efficiency, and while I can understand the technician’s reasoning to find the sweet spot, I cannot help feeling very disappointed and despondent about my new system. I came here to find out what other people’s views and opinions are of this and if this is normal and expected?

Thanks @Coulomb, I only saw your post tonight. I finally managed to solve the BMS communication problem after a LOT of effort and money (especially cables)! 🤪 First took the Dyness for a firmware upgrade at Rectron in Midrand. That alone wasn’t enough. Then had to wait for several RS232 comms cables to be delivered to be able to update the inverter firmware. So the most visible improvement on the display of the inverter is the flashing battery icon (sign of successfull BMS) and no charging when the battery is full. Before firmware update and BMS, the inverter appeared to be constantly charging the battery which didn’t feel right. But I didn’t know better at the time. In retrospect, I have learnt a lot and am grateful for the painful journey! 😜

The prolific driver tells me that the cable is counterfeit. The supplied drivers on the mini cd that came in the package is rubbish. It gave runtime error the moment you try to run the exe. Tried this on both Win 11 and Win 7, but still no joy. Downloaded latest drivers from prolific which gave me the counterfeit message in device manager. Downloaded an older version of the prolific drivers which installed fine and the port was visible in the reflash tool, but it just failed with an error saying that it cannot open the port. So I went and ordered the expensive cable from Solar Assist as suggested by @Douw Gerber, which arrived today. You get what you pay for: I just succesfully flashed the firmware and am now on the latest 71.97. Thought the display would also be updated, but it didn't. So I found the display reflash tool for the display panel in an earlier post and will flash that when my wife doesn't need the power. EDIT: Display is now also updated to 02.70 To confirm, are these the latest versions: CPU: 71.97 DSP: 02.70

Wish I listened to you and went for a db9 (male) to USB adapter....but instead I went for this that doesn't work: https://alcell.co.za/product/zatech-usb-to-rj45-control-cable-1-5cm/ I get an error from the flash tool saying it cannot open the port.

Thanks @Douw Gerber and @jumper! The firmware update would only be necessary as a last resort if I cannot get BMS between battery and inverter to work. Family helped me with a BMS cable that I will try out tomorrow. I just wanted to get the answers should I need to go down this route and know immediately what and where to buy from. But I would be glad if not necessary 😊