Afternoon, I have been quoted (year end "special" from a recognised installer) on a Sunsynk 5KW 1P HYBRID PV INVERTER 48C 5kw inverter plus 8 x 370w panels. I know these are not the latest and greatest panels but they come with the package.

I want to add an extra 2 x 370w panels (Taking total to 10), but installer is now telling me that I need to start another string due to limitations of the inverter. I don't believe this is true. Specs attached:  JAM60S21-370/MR panel  open circuit voltage of 41.3V and Inverter SS-1P-5K-H-48V - PV Input Voltage 370V(100v - 500V).

I don't want to start another string at this stage as I would prefer to keep MPPT2 free so that I can add different panels (say 455w) in the future.

What are the experts opinion?

Thanks!

380-Watt-Mono-Solar-Panels-Info-Sheet-1.pdf

That inverter can comfortably handle the extra 2 panels even more if you look at the voltage specified in the datasheet you shared.
But ideally you should balance the mppt's so 5 in a string on each mppt.
You can then still add more panels 2 at a time as you get more panels, 1 added to each mppt string till you max them out leaving a bit of leaway for cloudy days when the voltages may spike.
 

Edited December 10, 20222 yr by WannabeSolarSparky

Thank you. Yes I agree that I should balance between the two MPPTs. However I would then have 370w panels on each string, and as I understand it if I want to add panels later I would need to add 370w panels, as its not a good idea to mix different capacity panels on the same string.

I think the problem here is actual total wattage. The specs indicate a total input of 6300w. I initially read this as per MPPT, but apparently this is across  BOTH MPPTs. which is then 3250w per MPPT, which is 8 x 370w panels. 🤬

3 hours ago, WannabeSolarSparky said:

But ideally you should balance the mppt's so 5 in a string on each mppt.

I have to admit that I do not understand why MPPTs should be balanced

To gain max PV generation, I would rather put 10 panels on a single string instead of spreading them across 2

I am running one of my Sunsynks with 9x 480W on one MPPT and nothing connected to the other MPPT - and have absolutely no problems. I see not difference in behavior to my other Sunsynk that is running 6x 380W on each of it's MPPTs (facing different directions, hence on separate MPPTs)

1 hour ago, cecilh said:

I think the problem here is actual total wattage. The specs indicate a total input of 6300w. I initially read this as per MPPT, but apparently this is across  BOTH MPPTs. which is then 3250w per MPPT, which is 8 x 370w panels.

To my understanding the 6300W is max capability - but that does not mean that is 3250W per MPPT. As above, I am happily running 4320W on one MPPT

6300w is indeed the total max MPPT power of both. You can still add the 2 extra panels though. You will get better performance in cloudy conditions. You can exceed the max power input of the MPPT’s as long as the extra power is due to more current and not higher voltage. The inverter will just limit the current. Just do not exceed max voltage, that will blow it. In your case, the voltage is fine.

I currently only have 1 MPPT running on my 8kw because I am waiting for a specific size all black panel. It’s running perfectly fine. 

On 2022/12/10 at 7:27 PM, wolfandy said:

I have to admit that I do not understand why MPPTs should be balanced

To gain max PV generation, I would rather put 10 panels on a single string instead of spreading them across 2

I am running one of my Sunsynks with 9x 480W on one MPPT and nothing connected to the other MPPT - and have absolutely no problems. I see not difference in behavior to my other Sunsynk that is running 6x 380W on each of it's MPPTs (facing different directions, hence on separate MPPTs)

To my understanding the 6300W is max capability - but that does not mean that is 3250W per MPPT. As above, I am happily running 4320W on one MPPT

This is self made. MPPTs don't have to be balanced. That's why the inverter has 2 MPPTs so that different directions and different sizes and quantity can be used. 

Don't have to use old school of the same panels in multiple strings in parallel.