Will this set up work , need a little help here.

[Russelljw]

i have 4 rensola 300w 24v panels.
i plan on using 3 of the panels to give us extra power separate from the Motorhomes 12v power.
i have a 50amp mppt controller and four 6v batteries from a heavy duty fork lift ( don't know the amp hour rating on the batteries , I will look when I can) I'm sure it's over 100 each.
so , 24v battery bank with those.
i bought a 2500w 24v inverter.
i bought two 3branch 10awg connected to connect the panels , and 15 ft of 10awg to go from the panels to the controller.

question 1... Is the 10awg big enough?
2 ... Can I go 8awg from the controller to the batteries? Then 8 from the batteries to the inverter?
3... Fuses/ breakers , what size and where?
4... Will this work?
my family is moving off the grid for the summer! We need this power for vacuum, washing machine and charging stuff like phones and dewalts
i have a big 6500 diesel generator for back up.
thank you so much!

[sensij]

What specific controller do you have? If it has 150 Voc max input, and you have space, you would be well served to use all four panels in a 2x2 series-parallel configuration.

[Russelljw]

It's called y-solar got it off amazon , I know it's cheap but it is a true mppt.
it says 150vdc.

[sensij]

The chart here gives a good idea of what wire size you might need. If you intend to use anything close to the 2500 W the inverter is capable of, that is over 100 A and 8 awg is not even close to safe for use between the batteries and inverter.

[Russelljw]

So what size?

[Russelljw]

Also what about using 4 panels instead of 3?
i have 10awg from the panel to the controller , is that ok?

[sensij]

Also what about using 4 panels instead of 3?
i have 10awg from the panel to the controller , is that ok?

If you put two panels in series that gives about 90 Voc, 73 Vmp, 8.7 Isc, and 8.2 Imp. Put two of those strings in parallel, and the combined output is 73 Vmp and 17.4 Isc, and 16.4 Imp. If you are 15 ft from the panels to the controller, to keep voltage loss under 3% you'd need at least 10 Awg, so you are OK there. The wire should be rated to carry 17.4 * 15.6 = 27.1 A, so 10 Awg satisfied that as well. Since you just have two strings in parallel, no fuses are needed on the PV side of the charge controller.

The wires from the battery to the charge controller should have fuses on the terminals of the battery, these are good. How far from the charge controller to the battery? The charge controller is rated for 50 A output, and with 1200 W on a 24 V system, you might get close to that sometimes. By ampacity, you should probably by look at 4 Awg. For voltage drop, that would be good up to 25 ft.

The inverter is still the wild card. 2500 W is 104 A at 24 V. That would probably need at least 2 Awg. However, if your battery Ah isn't big enough to support that load, the voltage will crash if you try to pull it and the inverter will cut out. If that is the case, not much reason to invest in heavy wire if you can put smaller wire (appropriately fused) that is more appropriate for the load you will actually be running.

[Russelljw]

Thanks a lot.
i will be following your advice
, so a 50 a fuse between the controller and battery, closest to the battery?
and a 150a fuse between battery and inverter?

your also saying use the 4 panels and wire them in in parallel 2 to each string?
i should not be running anything over 1500 watts from that inverter, a 4 a water pump will be the biggest load I will have.

[Russelljw]

I should wire panels parallel one string if I use only 3 panels?

[sensij]

Where are you located? If it gets cold at night, below freezing, putting all three in series may exceed your voltage limit.

[Russelljw]

9000 ft up in Colorado , but this system is only for the summer.

[Russelljw]

I can't parallel 3?
sorry I'm new to this.

[littleharbor]

Paralelling these 24 volt panels wont raise the voltage, which you need with an MPPT controller. Series wiring 3 of these panes will give you a potentially high Voc for even a 150 Voc limit controller. Either 60 cell panels in a 3 panel (series) string or 4 of these in a 2s2p configuration would work

[sensij]

Paralelling these 24 volt panels wont raise the voltage, which you need with an MPPT controller. Series wiring 3 of these panes will give you a potentially high Voc for even a 150 Voc limit controller. Either 60 cell panels in a 3 panel (series) string or 4 of these in a 2s2p configuration would work

Huh? These are 72 cell panels, they produce enough voltage wired in parallel to support a 24 V battery for either PWM or MPPT. That downside to wiring three in parallel is that after they are combined, the circuit would have 26.1 A Isc, requiring wire rated to carry 1.56x that, or 40.7 A. That means 6 awg from the panel combiner to the charge controller, and each individual panel must be fused at 20 A max.

[Sunking]

Avoid Prime Number of panels except 1 and 3. If you use 3 the controller must have a high enough Voc input of 150 volts or higher.