October 5, 20232 yr Hi all, I am a newbie on this forum so I apologise if I am logging this request on the wrong group / topic. I have searched the forum but couldn't find a related thread, hence I am posting it on General I am installing a Solar system which consists of 1 x 8Kw single phase Sunsynk inverter which has 2 x MPPT charge controller's 10 x 450w Pannels (2 strings of 2250w each) 2 x BSL Powerline 5 kWh batteries. My question is as follows: Is it better to split the Solar input as to feed one 2550w string into each of the MPPT's or to feed both strings of 4500w into one MPPT and have the 2nd MPPT sit idle. The DC voltages of both options are within spec of the MPPT's
October 5, 20232 yr 10 Panels will be pushing the limits of the MPPT so i would go for 5 on each string .
October 5, 20232 yr I would also rather use 2xMPPTs than having 1 doing all the work and 1 idle. 10 panels in series can push the Voc to over 525V at zero degrees on a cold day. Based on Canadian panel specs. Edited October 5, 20232 yr by Scorp007
October 5, 20232 yr Author Thank you for the feedback.. I think I should check the exact spec of the Voc of the panels when they are delivered before deciding if I should use 1 or 2 MPPT's
October 5, 20232 yr Johan dT You ask for advice, you get good solid advice, yet you do not really want it. Of course, you should split the panels between the two MPPT's. Why on earth put all the power through one MPPT? Maybe because you can save a few bucks on Solar cable?
October 6, 20232 yr What if the 10 in series is safely under the V max: What configuration will start generation earlier and continue later? Do better during overcast? My 10 JA 535w 50v panels are connected 5 per string on two inputs (5kw Sunsynk inverter). The input string V is most of the time less than 210V and I have never seen it more than 230V (on a bright cold winter morning). The highest production I've seen was 4800w. I don't have any issues with my current setup, even on overcast days the base load gets covered and the battery gets charged by 13h00, where its normally charged before 10h00. But my panels are at 10 deg angle. 8 panels with brackets to 25 deg would have cost me the same as 10 panels flat on rails.
October 8, 20232 yr Wanting to do a similar setup to the above. Have enough roof space to fit 8x 550w panels or possibly more smaller panels. VOC on these panels is just shy of 50V - so 400V input. This seems in range from what I have read. Installer is saying that the MPPT startup voltage is too high for the amount of panels that I can fit and saying that I will have to go the 5KW inverter route - doesn’t really make sense to me. Can one run 2 strings of 4 panels in to each MPPT? Or would only 1 MPPT be able to be used?
October 8, 20232 yr On 2023/10/06 at 10:25 AM, Vaal said: What if the 10 in series is safely under the V max: What configuration will start generation earlier and continue later? Do better during overcast? My 10 JA 535w 50v panels are connected 5 per string on two inputs (5kw Sunsynk inverter). The input string V is most of the time less than 210V and I have never seen it more than 230V (on a bright cold winter morning). The highest production I've seen was 4800w. I don't have any issues with my current setup, even on overcast days the base load gets covered and the battery gets charged by 13h00, where its normally charged before 10h00. But my panels are at 10 deg angle. 8 panels with brackets to 25 deg would have cost me the same as 10 panels flat on rails. I wouldn't do 10 in series. The expected operating Voltage should be around 210V (based on Vmp of around 41.5V), so that is where you should see it most of the time anyway, that's not the issue. The concern is for not exceeding Voc of 500V, and 10panels x50Voc should sooner or later almost invariably exceed the limit. You only need to see it once. Also, even if you've never seen Voltage above 230V, your peak sunlight would be at the summer solstice around 21 December, in your case more so since your panels are oriented for peak summer generation, facing virtually 90 degrees straight on to the sun at mid-day at the peak. If not that, cooler clear weather or cloud edge brightness could cause you to exceed the limit. I think your best chance to get closer to optimum voltage is to add one more panel onto each string, and that would give you extra power in Winter when your panels are likely to a 25% drop in generation, but if you don't need the extra power, maybe just leave it.
October 8, 20232 yr Luckily one would only exceed the maximum once and blow the MPPT and learn what was the reason.
October 8, 20232 yr 7 hours ago, Scalpel said: Wanting to do a similar setup to the above. Have enough roof space to fit 8x 550w panels or possibly more smaller panels. VOC on these panels is just shy of 50V - so 400V input. This seems in range from what I have read. Installer is saying that the MPPT startup voltage is too high for the amount of panels that I can fit and saying that I will have to go the 5KW inverter route - doesn’t really make sense to me. Can one run 2 strings of 4 panels in to each MPPT? Or would only 1 MPPT be able to be used? 2 strings of 4 panels would battle to start. Without the specs of the panels just guesswork. My guess is 8 in series in the same direction would be fine. Lower output panels normally use more space for the same output. The shape of the roof comes into play. Edited October 8, 20232 yr by Scorp007
October 8, 20232 yr 1 minute ago, Scorp007 said: 2 strings of 4 panels would battle to start. Without the specs of the panels just guesswork. My guess is 8 in series in the same direction would be fine. Thanks. Think the installer was wanting to run both MPPT’s so was saying it wasn’t going to turn on. Want to rather buy once and get the 8kw, will look at trying to install more panels on the other available roof areas in the future if the need arises.
October 8, 20232 yr 1 hour ago, Scalpel said: Thanks. Think the installer was wanting to run both MPPT’s so was saying it wasn’t going to turn on. Want to rather buy once and get the 8kw, will look at trying to install more panels on the other available roof areas in the future if the need arises. You can put those 8 panels on one MPPT no problem. You do not have to use both MPPT's.
October 8, 20232 yr Thanks. Thought as much but just wanted to confirm. Roof orientation is North Facing (perfect for Durban) with a 30 degree pitch and no shadowing. Also have an East facing roof - so if I decide to add more panels it will be here but will start with the 8 panels for now.
October 10, 20232 yr Not to hijack the trend but also looking for some advice. I have a Sunsynk 8kw and would like to hook up 18x CS6U-330P Canadian panels (2 strings of 9x serial connected) on one MPPT. The other MPPT all ready have 9x 405W Canadian panels connected. CS6U-330P Nominal Max Power 330 Optimum Operating Voltage Opt (Vmp) 37,2 9x 334,8 Optimum Operating Current Otp (Imp) 8,88 2 17,8 Open Circuit Voltage open (Voc) 45,6 9x 410,4 Short Circuit Current Short (Isc) 9,5 2 18,9 Max Series Fuse Rating Could this work safely?
October 10, 20232 yr 55 minutes ago, Fred79 said: Not to hijack the trend but also looking for some advice. I have a Sunsynk 8kw and would like to hook up 18x CS6U-330P Canadian panels (2 strings of 9x serial connected) on one MPPT. The other MPPT all ready have 9x 405W Canadian panels connected. CS6U-330P Nominal Max Power 330 Optimum Operating Voltage Opt (Vmp) 37,2 9x 334,8 Optimum Operating Current Otp (Imp) 8,88 2 17,8 Open Circuit Voltage open (Voc) 45,6 9x 410,4 Short Circuit Current Short (Isc) 9,5 2 18,9 Max Series Fuse Rating Could this work safely? Yes that will work.
October 10, 20232 yr 1 hour ago, Fred79 said: Not to hijack the trend but also looking for some advice. I have a Sunsynk 8kw and would like to hook up 18x CS6U-330P Canadian panels (2 strings of 9x serial connected) on one MPPT. The other MPPT all ready have 9x 405W Canadian panels connected. CS6U-330P Nominal Max Power 330 Optimum Operating Voltage Opt (Vmp) 37,2 9x 334,8 Optimum Operating Current Otp (Imp) 8,88 2 17,8 Open Circuit Voltage open (Voc) 45,6 9x 410,4 Short Circuit Current Short (Isc) 9,5 2 18,9 Max Series Fuse Rating Could this work safely? More out of interest. Could you have a look on the side of the inverter if there's a plaque that defines the maximum power per MPPT. Bear in mind that I've got a 5kW Deye as a point of rerence, and it might not apply to you. In my case it relates to a maximum solar input of 6500W, of which the plaque says the split should be 50/50 per MPPT, or maximum 3250W per MPPT in a zero-export application. See Point 2 in the image below. This is not stated anywhere in other documentation with the inverter. In your case the Sunsynk's total power spec is 10400W, so if the same principle applies, then that would mean 5200W per MPPT. You are on 5940W. Before i get shot, I know folks have given various opinions, some do over-panel, some do have un-balanced solar per MPPT. My gut fears would make me probably stick to 16x330W panels in 8s2p layout, and hope that some systemic inefficiencies would limit the power that reaches the inverter.
October 13, 20232 yr Hi, I have 18 550w panels currently installed. What is the best configuration (busy debating with the installer). Roof Space available is 4 north, 7 west, 7 east. He has currently installed the 3 strings as above but north and east on 1st mppt and west on the 2nd mppt. I have 2 concerns, is the VOC (50 per panel) to high and is the different panel direction not a problem? help pls 8kw Sunsynk is the inverter. I have the option to change panels to 425w trinas which i am leaning to
October 17, 20232 yr On 2023/10/13 at 10:02 PM, Haggers said: Hi, I have 18 550w panels currently installed. What is the best configuration (busy debating with the installer). Roof Space available is 4 north, 7 west, 7 east. He has currently installed the 3 strings as above but north and east on 1st mppt and west on the 2nd mppt. I have 2 concerns, is the VOC (50 per panel) to high and is the different panel direction not a problem? help pls 8kw Sunsynk is the inverter. I have the option to change panels to 425w trinas which i am leaning to do you only have 2 mppts? what about taking 2 each of north and add on west and east string (mmpt) respectively - then 9 per mppt - that is 450v max? then put optiimisers on the 4 north ones so they dont drag down early and late sunpower?'(depends on panel distances ?) 11x50 - 550v 7x50 =350 what can the sunsynk handle - 425?? check that ps - i am purely a user of solar ..not an engineer but had the same string balancing issues so had to figure it out..
October 20, 20232 yr 1 hour ago, Fred79 said: @GreenFields This is what I can see on the side of the inverter. Thanks a lot. If that is the only sticker, nothing below it that speaks of the limit per MPPT, then that satisfies my curiosity.
October 21, 20232 yr 2 hours ago, Chris_S said: I wonder why my sunsynk 8K has higher PV current specs? I have it the current versions has a 22A per MPPT. The picture from @Fred79 shows a very high 90A pass through while some other units only have a 53A😀😀😀 Edited October 21, 20232 yr by Scorp007
October 21, 20232 yr 4 hours ago, Scorp007 said: The picture from @Fred79 shows a very high 90A pass through while some other units only have a 53A😀😀😀 Maybe their data ain't all that honest/cut & dried... I suspect the pass through is only 50-odd Ampere and with the inverter able to produce 35-odd Ampere, then you're at app. 90 Ampere, I sincerely doubt they would be able to pass 90 Ampere from the utility end, specially since most houses here have a 60-odd amp limit from the municipal end...
October 22, 20232 yr I remember reading somewhere that this was a misprint or it was meant to be on the 3 phase inverter or something like that. They even had it printed in some of the old manuals for the 8Kw unit
October 23, 20232 yr On 2023/10/21 at 8:00 AM, Scorp007 said: I have it the current versions has a 22A per MPPT. The picture from @Fred79 shows a very high 90A pass through while some other units only have a 53A😀😀😀 Even though mine says 22A it clips at 20A
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