Higher Volts or Amps

[Wescottpower]

For some reason my search function isn't working, it goes to an Oops page. I'm sure this has been covered already somewhere on here so sorry in advance!

What is better for efficiency when combining panels for your PV input circuits? I have 6 550w panels per PV input (2 inputs). I can either wire 3 panels in series and parallel another 3 panels to get me closer to my max input voltage (149.9v/28.02A) or series 2 panels and parallel three pairs to get closer to my max amp input (99.8v/42.3A). Each PV input is good to 155v and 60 amps. It's a 48v system, 12k 240 split-phase output.

Those numbers above are Voc and Isc calculations and max wattage per PV is 3500w

 

[Tomthumb62]

I can either wire 3 panels in series and parallel another 3 panels to get me closer to my max input voltage (149.9v/28.02A)

What is the max PV voltage input for your charge controller. You CANNOT exceed this. If it’s 150v, then 149v is way way way too close.

 

[Brucey]

149V could go over 155V when temps get colder prob want more of a safety margin.

 

[Wescottpower]

What is the max PV voltage input for your charge controller. You CANNOT exceed this. If it’s 150v, then 149v is way way way too close.

155

 

[Wescottpower]

What is the better option if I wasn't getting too close to the max inputs? is it better to have higher voltage or amperage?

 

[Tomthumb62]

155

Still way too close. What’s the coldest recorded temperature in the past 75 years where you will use this system? Volts go up as the temperature goes down. If you exceed that number, you’ll fry the controller.

 

[Tomthumb62]

What is the better option if I wasn't getting too close to the max inputs? is it better to have higher voltage or amperage?

Higher voltage is better. Because you can use smaller wire.

 

[Wescottpower]

Right, I size wire for the maximum circuit amperage anyways, but as far as what is better (more efficient) for charging?

 

[Tomthumb62]

Right, I size wire for the maximum circuit amperage anyways, but as far as what is better (more efficient) for charging?

Doesn’t matter.

Because your MPPT charge controller is going to take X volts and Y amps and magically transform them into the appropriate charging profile for your battery, according to the settings.

 

[Shimmy]

It is marginally more efficient to have your PV voltage at about 2-3x your battery voltage, but not a huge difference. You either loose it in voltage drop or MPPT efficiency.

 

[Tomthumb62]

You either loose it in voltage drop or MPPT efficiency.

Which can be fixed by adding another panel or few, depending upon the size and configuration of your system.

 

[Wescottpower]

Awesome, thats very helpful thanks for the replies. I went conservative and did the 2 series and 3 parallel (99.8v/28.02A). I was doing the math and thought I could get away with the higher voltage but yes Brucey and TomThumb it does get cold here.

Thanks for your time everyone, appreciate the help!