Posted April 9, 20232 yr I've been participating quite regularly on the forum for a short while now, but earlier this week I finally got my setup installed and comissioned. Some information: Sunsynk 8kW Inverter 2 X Greenrich WM5000 wall mount batteries 10 X Longi 555W panels, all facing north. I was originally planning on going 6+6, with one string facing north and another facing east/west due to size constraints on my north-facing roof. But the installers managed to fit 10 on the north facing roof alone, and we reckoned 10 facing north is better than 6 facing north and 6 facing east/west. I was considering buying 8 more, and put another 10 on the other roof so that I can use the other MPPT as well, but that might come in the future, pending my actual usage patterns. Solar generation is good so far, and in fact it seems over specced. On sunny days I have this large notch in the middle of my PV graph. The batteries are recharged by 10h, and the rest of the day's loads are quite low. I have my geyser connected to the inverter Aux port, as a semi-critical load. I'm still playing around with the settings to find the most optimal configuration, but so far it seems like it's working. I've made another post explaining how I set things up. I reduced the geyser element to 2kW, so that when it runs it can run 100% off solar. I don't want to cycle my batteries during the day for hot water. The geyser thermostat is also set as high as it can go, so that it can act like a thermal battery of sorts, taking up more of that sunshine if the rest of my loads don't call for it. Total outlay was just north of R200k. I purchased the expensive equipment myself (inverter+batteries+pv), and contracted an installer to do the actual installation for me.
April 20, 20232 yr Congratulations on your installation sir! You may want to confirm with your installer if 10 panels on one mppt could exceed the max voltage on a cold sunny day.
April 21, 20232 yr 17 hours ago, zathras said: Congratulations on your installation sir! You may want to confirm with your installer if 10 panels on one mppt could exceed the max voltage on a cold sunny day. Mmmhhh, I tend to agree with this. I've been agonizing over the MPPT voltage range as well. For the 8kw ( which I'm also planning to use ) the MPPT voltage range is 125-425V which I assume is a WORKING or OPERATING voltage, not the maximum. So for this setup the 10 panels deliver 421V at maximum power but the Current To Voltage curves show that the voltage rises as the current drops (e.g. when the battery is just about full and no other loads are being driven) and it doesn't take much for the operating voltage to go over the 425V value of the MPPT. I am not sure exactly what the consequences will be - in light of the datasheet and installation manual seemingly emphasizing the Max Open Circuit Voltage. As for the maximum open circuit voltage - for 10 panels it is already at 499.5V at 25 degrees. So if the temperature drops even by 5 degrees to 20 degrees the max open circuit voltage will be exceeded (0.3% per degree) . I really think SUD7162 should revisit the installation - just to be on the safe side. Edited April 21, 20232 yr by TestTube correct max open circ v
April 26, 20232 yr Snap, very similar system. Install is being finished today, but had hot coffee this morning during LS.. Happy days 🙂
April 26, 20232 yr Author I asked the installer about the 10 panels in series thing. My VOC is 499V, and the max voltage for the MPPT is 500V according to the sticker. I have not had any over voltage faults logged for on the inverter yet. Supposedly the Sunsynk will log a fault and shut the PV down if it over-volts. The installer said it's fine, and not a problem and that things will be safe. I said if the magic smoke comes out, I will be phoning them. I'll see how things go over the winter. I'm in Pretoria, the temperature rarely (if ever) dips below 0C when the sun is actually out. IMO these temperature offset calculations are a bit overblown in my opinion. I think it becomes a real big issue when it's really cold outside, like double digits cold, and the sun pops out from behind a cloud. I have seen PV temperatures as high as 490V in practice, so I'll keep an eye on it. Interestingly, the one day where it was cloudy and the sun popped out, my system overproduced by about 500W, generating 6.1kW instead of the 5.55kW nameplate. It was quite cool that day. The PV voltage during that peak was only 400V, which is quite lower than the norm.
April 26, 20232 yr Author PS. I actually hate these sharing of installation pictures. I now notice my batteries are not grounded, and wonder if they should be? The situation with installers and the standards are so out of whack at this time, everyone has a different opinion.
April 26, 20232 yr 1 hour ago, suds7162 said: PS. I actually hate these sharing of installation pictures. I now notice my batteries are not grounded, and wonder if they should be? The situation with installers and the standards are so out of whack at this time, everyone has a different opinion. Pictures make me jealous even though my installer did a really neat job - more my house is the injustice to their work After prepping my house for a new COC, everything needs to be earthed even in Cape Town. It feels like you need to earth the earth.
May 1, 20232 yr Author Earthing is another thing I don't even want to get into. Asked my installer about that, and he responded sarcastically "Do you want to conduct electricity from your panels into the inverter?". My array is unearthed at the moment. Only the inverter and associated DB boards are earthed. Apparently the right way to do it is to bond the panel earth to the house DB earth, which makes zero sense to me. As that will guide lightning from the panels right into the db board where it can go and do more damage. So frustrating.
May 1, 20232 yr 57 minutes ago, suds7162 said: Asked my installer about that, and he responded sarcastically "Do you want to conduct electricity from your panels into the inverter?". My array is unearthed at the moment. Only the inverter and associated DB boards are earthed. Naughty installer! putting 10 of those panels on a string ... Not earthing solar panels ... 😬
May 3, 20232 yr I would climb up and disconnect 1 panel with winter cold coming. Sounds like your installer will run away if that mppt pops. And sunsynk won't warrant that claim.
May 3, 20232 yr On 2023/04/26 at 11:43 AM, Garthox said: Very nice installs @BruceK @suds7162 All done and running beaut. Cleaned up the cabling on the batteries a bit and looks real neat now. Very happy.
May 5, 20232 yr I like, pretty much the identical system that's coming my way next week. I'm also in Pretoria and I have to agree about the weather that we have here. PS, I approve the colour coordinated cabling on the LHS....it's all about detail. 🙂
May 18, 20231 yr On 2023/04/21 at 5:57 PM, TestTube said: Mmmhhh, I tend to agree with this. I've been agonizing over the MPPT voltage range as well. For the 8kw ( which I'm also planning to use ) the MPPT voltage range is 125-425V which I assume is a WORKING or OPERATING voltage, not the maximum. So for this setup the 10 panels deliver 421V at maximum power but the Current To Voltage curves show that the voltage rises as the current drops (e.g. when the battery is just about full and no other loads are being driven) and it doesn't take much for the operating voltage to go over the 425V value of the MPPT. I am not sure exactly what the consequences will be - in light of the datasheet and installation manual seemingly emphasizing the Max Open Circuit Voltage. As for the maximum open circuit voltage - for 10 panels it is already at 499.5V at 25 degrees. So if the temperature drops even by 5 degrees to 20 degrees the max open circuit voltage will be exceeded (0.3% per degree) . I really think SUD7162 should revisit the installation - just to be on the safe side. Keith from Sunsynk said in one video that although the SunSynk is rated for 500V Open Circuit Voltage, one should not go above 450V. To High Volts over electronics components is a big no no.
May 22, 20231 yr Author On 2023/05/18 at 8:49 PM, FvA said: Keith from Sunsynk said in one video that although the SunSynk is rated for 500V Open Circuit Voltage, one should not go above 450V. To High Volts over electronics components is a big no no. But then in another video he says the inverter has an overvoltage cutout of 520V. I have my salt-shaker next to me when I watch his videos 😂
June 4, 20231 yr OP you mention that the AUX is working as it should. How have you set this up and how exactly is it working? Amazing install btw! 👌
June 4, 20231 yr Can you mount these batteries up side down? reason I'm asking is I want to mount my battery above my inverter. The inverter will be eye level with battery above and it would be easier to reach the battery switches if upside down.
January 28, 20241 yr On 2023/04/21 at 4:57 PM, TestTube said: So for this setup the 10 panels deliver 421V at maximum power but the Current To Voltage curves show that the voltage rises as the current drops (e.g. when the battery is just about full and no other loads are being driven) and it doesn't take much for the operating voltage to go over the 425V value of the MPPT. I am not sure exactly what the consequences will be - in light of the datasheet and installation manual seemingly emphasizing the Max Open Circuit Voltage. I was also advised by Sunsynk back in 2022 when I done a 8KW Sunsynk with 20x450W panels not to go more than 8 in series as this voltage was too close to maximum MPPT range. I than ended up wiring 4xstrings with 5xseries panels, this gave me a voltage of 220V per MPPT. I would recon if suds7162 could split the 10 x panels into 2x strings of 5xpanels and still keep them facing North it would take him out of the risky zone of blowing the inverter, but this would mean pulling extra set of solar cables to combiner box and extending the combiner box to accommodate the second string.
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