July 31, 20233 yr Newby here and need your advice please guys. I bought a 5.5kw Sunsynk inverter and need to find a good match in terms of PV panels. Was looking at 10 x 550w Canadian Solar Hiku6 Mono Perc panels in a 2 string setup. Would that be OK? What would a better alternative be? Probably dumb questions but I am hearing conflicting (horror) stories. Any advice would be much much appreciated.
July 31, 20233 yr 5 hours ago, Jaco newbee said: Newby here and need your advice please guys. I bought a 5.5kw Sunsynk inverter and need to find a good match in terms of PV panels. Was looking at 10 x 550w Canadian Solar Hiku6 Mono Perc panels in a 2 string setup. Would that be OK? What would a better alternative be? Probably dumb questions but I am hearing conflicting (horror) stories. Any advice would be much much appreciated. I wonder what these horror stories are? Do you intend using 1 MPPT per string?
August 1, 20233 yr Author Apparently the inverter can't handle these panels and the MPPTs go up in smoke? Was planning on 2 x strings of 5 panels each running to individual Mppt. Open to suggestions though.
August 1, 20233 yr 49 minutes ago, Jaco newbee said: Apparently the inverter can't handle these panels and the MPPTs go up in smoke? Was planning on 2 x strings of 5 panels each running to individual Mppt. Open to suggestions though. These panels can be used but you can only use them in series per MPPT. Up to about 8 in series per MPPT. Thus a maximum of 16 on the inverter. For now you can add 5 in series per MPPT. The inverter can only accept about 13A input per MPPT. Using 2 string in parallel would mean you input about 26A per MPPT and 50% will not be used and I think risky to think the inverter must absorb 50% of the extra current it cannot use. The inverter can I any case only take 6500W of panels being 12. You might be able to push it to 7 per MPPT. Just connect them correct and all will be fine. Edited August 1, 20233 yr by Scorp007
August 3, 20233 yr Author Thanks. Appreciate your feedback! Have you done an install similar to this? Edited August 3, 20233 yr by Jaco newbee
August 3, 20233 yr 41 minutes ago, Jaco newbee said: Thanks. Appreciate your feedback! Have you done an install similar to this? No i don't do any installations. Not too difficult to read the specs and choose panels that fall within the specs for proper operation. Ignore the 14-16 panels and stick to 12. 6 in series to each MPPT. Incomplete answer as no specs provided for the panels. All estimates. Edited August 3, 20233 yr by Scorp007
August 3, 20233 yr @Scorp007 @Jaco newbeeCanadian 550MS specs: Voc - 49.6v Vmp - 41.7v Isc - 14A Imp - 13.2A
August 3, 20233 yr 1 minute ago, TaliaB said: @Scorp007 @Jaco newbeeCanadian 550MS specs: Voc - 49.6v Vmp - 41.7v Isc - 14A Imp - 13.2A Good. Imp spot or what the 5kW Sunsynk can use.
August 3, 20233 yr On 2023/08/01 at 6:37 AM, Scorp007 said: Up to about 8 in series per MPPT Spot on 8 x 49.6= 396.8 +7%=424.6v 7% = 0°C Edited August 3, 20233 yr by TaliaB
August 3, 20233 yr 2 minutes ago, TaliaB said: Spot on 8 x 49.6= 396.8 +7%=424.6v 7% = 0°C Yes but inverter can only accept 6400W of panels. That's why I changed from 7/8 down to 6 if both MPPTs are in use Edited August 3, 20233 yr by Scorp007
August 3, 20233 yr 6 minutes ago, Scorp007 said: Yes but inverter can only accept 6400W of panels. That's why I changed from 7/8 down to 6 if both MPPTs are in use That’s not exactly correct. The inverter can only process 6500W PV power. You can put more potential power in panels, as long as you don’t exceed the maximum voltage per MPPT and the current is close to the MPPT range. On a 5kW SunSynk, you can put 2 strings of 8 x CS 550W. Total 8800W. This is still within the acceptable values for the inverter. It will draw at most 6500W but you will have extra power in cloudy days.
August 3, 20233 yr On 2023/08/01 at 6:37 AM, Scorp007 said: I think risky to think the inverter must absorb 50% of the extra current it cannot use. The inverter does not absorb any extra current. Such current is never produced because the resistance on the MPPT won’t allow it. Panels don’t produce current. They produce voltage. Current flows based on resistance of the load. I=V/R Edited August 3, 20233 yr by PowerUser
August 3, 20233 yr 28 minutes ago, PowerUser said: The inverter does not absorb any extra current. Such current is never produced because the resistance on the MPPT won’t allow it. Panels don’t produce current. They produce voltage. Current flows based on resistance of the load. I=V/R Can you explain the reasoning that we see specs of the maximum Isc of panels connected to MPPTs. Another stupid question. If the panels produces say 200V early in the morning why can't it send current out if i place a load on the leads directly. This without a controller. Edited August 3, 20233 yr by Scorp007
August 3, 20233 yr 2 minutes ago, Scorp007 said: Can you explain the reasoning that we see specs of the maximum Isc of panels connected to MPPTs. You see Isc specs on the panels. Not on the MPPT. The spec on the MPPT is for Imp in order to match the best panels for what your MPPT can draw. It is not good to connect panels with Imp of 8A to a 13A MPPT because even at full power these panels won’t reach the power potential of the MPPT. Also, it’s not good to connect panels with 16A Imp to a 13A MPPT because in that case, your MPPT won’t be able to draw the full power from those panels. Look at it this way - you have a main MCB from Eskom coming to your house at 63A. If you connect just a fridge and nothing else, you will draw let’s say only 1A. The fridge does not absorb the rest 62A of the current from Eskom and it won’t get damaged. It just doesn’t draw the extra power. The same happens if you have panels which can provide more current connected to a lower spec MPPT.
August 3, 20233 yr 5 minutes ago, PowerUser said: You see Isc specs on the panels. Not on the MPPT. I used an example of no controller. If I place a 100 ohm resistor over the panels that are at 200V early in the day you won't get 2A flowing. If I connect it over 200V from a plug point 2A will flow. These specs are MPPT related and not solar panel.
August 3, 20233 yr 17 minutes ago, Scorp007 said: I used an example of no controller. If I place a 100 ohm resistor over the panels that are at 200V early in the day you won't get 2A flowing. If I connect it over 200V from a plug point 2A will flow. These specs are MPPT related and not solar panel. As far as I know, sometimes the MPPT short circuits the PV in order to prevent battery charge. In this case the Isc of the panels shouldn’t exceed the Isc of the spec above.
August 4, 20233 yr 16 hours ago, PowerUser said: As far as I know, sometimes the MPPT short circuits the PV in order to prevent battery charge. In this case the Isc of the panels shouldn’t exceed the Isc of the spec above. Yes we read here it is common for the MPPT to prevent battery charging - it is when the MPPT goes up in smoke Something @WannabeSolarSparky placed last year what causes too much current to the MPPT and end result.
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