Expanding Small Array

[Massey44]

Iv got a Epever 4210an

Rated charge current 40A
Rated charge power 520w/12v 1040w/24v
Max. PV array power 780w/12v 1560w/24v
Max. PV open circuit voltage 92v @ 25°C 100v @ minimum operating environment temp.

I currently have four 100w 12v solar panels

Max. Power 100w
Rated voltage (Vmp) 17.1v
Rated current (Imp) 5.5A
Open circuit voltage (Voc) 21.5v
Short circuit current (Isc) 6.1A

Right now they are 2S2P to make 24v 11Amps. I would like to add 4 more identicle panels. What would be the best way of doing this with using just one charge controller if possible. If you need anymore information, let me know.

 

[sunshine_eggo]

Iv got a Epever 4210an

Rated charge current 40A

Rated charge power 520w/12v 1040w/24v

Max. PV array power 780w/12v 1560w/24v

These are BATTERY voltages, not panel

Assuming you have a 12V battery.

Max. PV open circuit voltage 92v @ 25°C 100v @ minimum operating environment temp.

I currently have four 100w 12v solar panels

Max. Power 100w
Rated voltage (Vmp) 17.1v
Rated current (Imp) 5.5A
Open circuit voltage (Voc) 21.5v
Short circuit current (Isc) 6.1A

Right now they are 2S2P to make 24v 11Amps. I would like to add 4 more identicle panels. What would be the best way of doing this with using just one charge controller if possible. If you need anymore information, let me know.

Anything over 520W will be wasted, but you will make 520W longer with a larger array.

800W is over the 780W max PV array power, but I personally wouldn't be concerned.

4S is too high a voltage for your 92V limit.

2S4P is the most practical way.

Another option would be to add TWO more and go 3S2P

 

[Massey44]

I appreciate the schooling, would you personally set them up 2S4P or 3S2P. I already have 2 more panels. If the most reliable way is to get another charge controller and 2 more panels then I could just hook up 3S2P for now. But if 2S4P would be reliable then I could aim for that and still get another charge controller and 8 more panels to double everything one day in the future.

 

[sunshine_eggo]

Either option would be reliable.

2S4P (or 2S3P) would be best in situations of shading or partial shading. Down sides: 1) the lower voltage and higher current means higher wiring losses and 2) 3 or more strings in parallel require a fuse on each string.

3S2P would be give slightly less conversion efficiency, but would reduce wiring losses, and 2P does not require fuses. Allegedly, they will start charging slightly before and slightly later than a 2S4P array, BUT this is ultimately a very small total amount of energy. Some folks over-state the value of higher voltage. It would also be less shade/partial shading tolerant.

600W vs. 520W maximum output means you'll rarely lose anything because arrays rarely output their maximum.

 

[Massey44]

Iv got 2 AWG copper running roughly 50 feet from my house. I don't know for sure, but I can't imagine the losses will be very high in either array configuration. I also don't know what my limit would be with the 2 AWG, I used it because I had it around. For 2S4P what would be an appropriate size wire running 50 ft? 6 AWG?

 

[sunshine_eggo]

2S2P, 0.5% drop:

Voltage Drop Calculator

This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.

www.calculator.net

2S4P will be less than 1.01% because you'll never actually draw full current from the array due to the MPPT output limitation (520W).

By NEC 3% loss limit, at 2S you'd be good up to 12P (66A)

Voltage drop with PV is more about what you're willing to tolerate. For a long run, 10% is reasonable.

3S2P would be 0.34% w/2awg.

Given your high northern latitude, I think I'd even consider 3S3P on that controller favoring a year-round winter tilt.

 

[Massey44]

I will aim for 2S4P but might experiment abit just so I can wrap my head around learning all this abit better.