Need help upgrading my 1200AH 12V to 48V system

[gnoeld]

I currently have twelve 12 volt 100ah lead acid battery bank (1200AH). I want to wire 4 batteries together for 48 volts making three 4 battery packs @48v then wire them in parallel.
All my wiring for batteries is 2/0 gauge and my CC is 60amp Renogy MPPT. I am replacing my 12V inverter with 48V
Will my 2700 watt Panels that are currently charging my 12 volt array charge the 48V system well?

 

[Al D]

What's the voltage of your panels? Are they all the same panel?

 

[gnoeld]

6 panels
MP 250 Watts
Open CV 37.6
Voltage at Pmax 30.3
SCC 8.85 amps
Current at Pmax 8.27
Max system Voltage 600V

4 panels

Maximum Power	300 watts
mperage Capacity	‎3.12 Amps
Maximum Voltage	‎18 Volts

Cheap China flex panels

 

[MichaelK]

With my routine calculations, I like to use an 1/8thC charge level, and I like to include an 85% derating for real-world output. The math for your reorganized bank would be (100Ah X 4 strings)/8 = 50A. 50A X 50Vcharging = 2500W. 2500W with 85% derating is 2500W/0.85 = 2940W.

How exactly are you wiring together the strings of panels? Seems the voltages aren't matching up too closely. 60cell panels are dirt-cheap right now. If the voltages are not well matched, you might be better off ditching the 12V panels and getting another 6 of the 250W ones. Five of the 18V ones would match up better with three of the larger panels.

 

[Al D]

I didn't see if the charge controller you have is a boost controller or not, so you should probably wire your panels such that the output voltage is more than 48V.

If you're comfortable doing so, connect three of your 250W panels and two of your 300W panels in series. Make two of these strings and wire in parallel.

This configuration results in fairly high voltage. You'll be approaching the max input of your charge controller. You might exceed that input on a very cold and clear day.

 

[gnoeld]

I appreciate all that information and will look into how my panels are currently wired. I need help with wiring my 12 batteries in series and parallel to create 48 V from my 12 V system
I also need advice on fusing the battery bank and inverter

 

[MichaelK]

I didn't see if the charge controller you have is a boost controller or not, so you should probably wire your panels such that the output voltage is more than 48V.

If you're comfortable doing so, connect three of your 250W panels and two of your 300W panels in series. Make two of these strings and wire in parallel.

This configuration results in fairly high voltage. You'll be approaching the max input of your charge controller. You might exceed that input on a very cold and clear day.

I think this is his controller. Not the lower cost budget unit that's only 100V. Can you please reconfirm this? With a 150V limit, three of the 250s in series for 90V would be good. But, I'm suspicious of the numbers for the 300W panels. 3.12A at 18V can not be right? I would NOT put the 250s and 300s in any kind of series configuration until you have the correct specifications.

 

[gnoeld]

I have two Renogy 60 amp MPPT charge controllers
I am using one controller on the six 250 watt panels wired 3 in a series and then the two series arrays in parallel for 104 volts 18 amps
The second controller is hanleling the four 300 watt chinese flex panels in series

 

[gnoeld]

Is there a diagram for wiring (twelve 12 volt batteries)) 12V batteries to 48 Volts that I can look at?
I know I have to wire 4 in series ( Three times ) but I need to see the parallel connection. Thanks

 

[Al D]

If you had four 12V batteries, you would connect the positive of the first battery to the negative of the second, the positive of the second to the negative of the third, the positive of the third to the negative of the fourth. The negative of the first battery would be the negative of the whole battery. The positive of the fourth battery would be the positive of the whole battery.

Parallel connections:
With three sets of that configuration, you would then hook up all of the "whole battery positives" of each set together, and then all of the "whole battery negatives" of each set. Using a busbar may be helpful, but you can use multiple wires if that's all you have.

I'm sure there are youtube videos showing parallel connections of a series circuit. (Search that for more information)

 

[gnoeld]

If you had four 12V batteries, you would connect the positive of the first battery to the negative of the second, the positive of the second to the negative of the third, the positive of the third to the negative of the fourth. The negative of the first battery would be the negative of the whole battery. The positive of the fourth battery would be the positive of the whole battery.

Parallel connections:
With three sets of that configuration, you would then hook up all of the "whole battery positives" of each set together, and then all of the "whole battery negatives" of each set. Using a busbar may be helpful, but you can use multiple wires if that's all you have.

I'm sure there are youtube videos showing parallel connections of a series circuit. (Search that for more information)

Thanks for your help