Hello
I have solar panel Longi 450Wp in 3 series and 5 parallel configuration. MPPT Victron Smartsolar 250/100. Distance between MPPT and Solar panels is 25 m (82ft). Solar cable is 6,0 mm2.
Where is the best location to connect parallel arrays with MC4 Y connectors, under the roof or close to the MPPT?
Wery thanks, Best regards Miro
In a "general" sense it would be preferable to keep the voltage high and current low for as long as possible. So, where you are introducing "Y" connectors you are adding current of the 2 branches, I would therefore position them as close to the charge controller end as possible.
6mm2 cable (10AWG) is ok for max 30A, your 3 series, 5 parallel setup (15 panels?) will most likely exceed that at some point in the chain with multiple Y connectors, plus the Y connectors themselves have a current limit.
Thank you, I understand. So I place all the MC4 Y connectors near the MPPT and connect the cables separately from each parallel array of panels.
Or I will connect only parallel fields under the roof. 1-2, 3-4.
I use MPPT 250/100 , for 25m (82 ft) length AWG 10 cable is better connect in serial 3 pcs or 4 pcs solar panels ? For Longi 450Wp and MPPT 250/100 is maximum 4pcs solar panel in serial connection (about 200V)
I had a look at the data-sheet for those panels. For the MPPT 250/100 you have then you could put 4 panels in series? It would make sense then to have an array based on strings of 4 panels, either 12 or 16?
So, as an example, if you added one more panel(total 16), you could have 2 strings feeding into one Y connector with that 6mm2 cable, to a short bus bar, the other 2 strings of 4 feeding another Y connector to the same bus bar. Or just terminate all string feeds on a bus bar and do away with the Y connectors... ?
Either way your Isc for each string would be 11.6A (+ temp coef factor), which for 4 strings would be 50A(round figures). On that basis I would be looking at 6AWG, 16mm2 cable for the last run to the charge controller.
Hope that helps.
