Solar design-series or parallel

[Edsashley]

I have a kit coming;
9 x Trina vertex 385w all black panels
3.6kW solis hybrid inverter
Pure drive pure storage 5kW battery

My question is , my designer has provided a design and schematics for the entire system however I notice he has a string of 4 panels with a string of 5 panels in parallel.
After some research I have come to the understanding that each string should really consist of the same number of panels.
If this is the case do I try and get an extra panel and fit two strings of 5 panels or simply fit a single string of 9 panels.
Connecting wire is 4mm2 so will handle the current.
Can anyone pitch in with their ideas, it would be greatly appreciated.

 

[Jim Burrow]

Do your best to have all strings close to the same open circuit voltage. The parallel panel(s) output voltages will try and drop to the lowest voltage of any string in your parallel system. - just like batteries do. Example. three strings connected in parallel, one at 40vdc, the second at 39vdc and the third at 30vdc. The output voltage of the three strings in parallel will try and drop to 30vdc.

 

[HRTKD]

That Solis Hybrid Inverter has two MPPT ports. So two strings of different output shouldn't be a problem.

Solis 3.6kW Single Phase Solis Solar Inverter 2 MPPT 208/240VAC with internal Sunspec MLRSD transmitter. (SKU Part Number Solis-1P3.6K-4G-US-SPRT)

3.6kW Single Phase Solis Solar Inverter 2 MPPT 208/240VAC with internal Sunspec MLRSD transmitter. (SKU Part Number Solis-1P3.6K-4G-US-SPRT)

thepowerstore.com

 

[Jim Burrow]

That Solis Hybrid Inverter has two MPPT ports. So two strings of different output shouldn't be a problem.

Solis 3.6kW Single Phase Solis Solar Inverter 2 MPPT 208/240VAC with internal Sunspec MLRSD transmitter. (SKU Part Number Solis-1P3.6K-4G-US-SPRT)

3.6kW Single Phase Solis Solar Inverter 2 MPPT 208/240VAC with internal Sunspec MLRSD transmitter. (SKU Part Number Solis-1P3.6K-4G-US-SPRT)

thepowerstore.com

Great. As for me, I only have one PV input port on my little 3434lv controller/inverter. So, it is important for me not to have a mismatch in solar panels. However, in reality, in my case, there is a big tree in the neighbor yard that in the late afternoon starts to shade my 6 panels one at a time. So, by the time 3 or more of the panels are shaded, my panels are down to 34 vdc and either the battery is helping to supply power to the house load, or the Utility has kicked in and now suppling power to the load and solar to charge the battery if it can.