Series to Parrallel

[zant69]

Have 2 strings of 8-305w panels in series-280v/9amp....can I combine with a parralell connector and have 280v and 18amp--going into EG4 500/100 controller-Thx

 

[SunDave]

Check out the spec sheet. You didn't list a link or exact model number so it's hard to say. However if it is the spec sheet I looked it it said it can use 18amps max, but your solar array can be up to 22amps. With the last 4 amps not being usable, but still safe for the controller.

So, from the information you gave, it looks like you have a great plan.

 

[glandpuck]

Yes you can as long as you remain within the specs for the MPPT charger. Fuse the PV+ and PV - from each string with a 15 amp solar fuse. Then connect the PV- to a common buss bar ( optionally, you can use a double pole DC breaker for PV+ and PV- or a single pole breaker for just the PV+) and then connect both PV- to a common buss bar and the output to the MPPT controller terminal. Do the same for the PV+ after they exit the DC breaker. The breaker should be 15 amps 600 volt rated. Then the PV+ from the buss bar should be fused at 25 amps 600 V DC and best practice a breaker to those specs too. Then PV+ out from breaker to MPPT charger terminal. This method protects against quick amp changes with the fuses and over current protection with the breakers.

 

[SunDave]

Hi gland. I would suggest keeping it simple in this situation. Since two strings do not require fuses, and the MPPT charge controller has a built in breaker, the OP could use an MC4 Y cable, or combiner box (personal preference), then run them right into the charge controller once combined.

The reason I push for simplicity is that adding extra connections can add failure points.

 

[zant69]

Thx for answers,trying to free up a CC for more panels.

 

[glandpuck]

Hi gland. I would suggest keeping it simple in this situation. Since two strings do not require fuses, and the MPPT charge controller has a built in breaker, the OP could use an MC4 Y cable, or combiner box (personal preference), then run them right into the charge controller once combined.

The reason I push for simplicity is that adding extra connections can add failure points.

Ah. these are good points that you make.

By having the system fused and breakered, there is way more protection from installation faults and panel faults. I also look at it from the point of view that if I did a good job, I may not have any diagnostics to do for 10 years. And when I do, I want to be able to isolate the problem as easily as I can.

Also, for me, I am older. This means the home will either pass to my family or be sold. I want it to be in tip top shape and pass any inspections. I also don't want my family reminded about the botch jobs I left all around the home.