Best Way to Join Two 8S Packs With Two 8S BMS's

[John Frum]

I think I bought some 30A inline fuse holders but they won't work for the 12 awg will they?

Correct.

I have a couple of 63A circuit breakers I was going to use between the solar panels and the solar charge controller.

The you need to use 6 awg wire between the combiner box and the solar charge controller.
Also you can't do 6p with 63 amp breaker.
Is it a double pole breaker with sufficient voltage rating?

 

[John Frum]

I think you should upgrade your SCC so that you can do 2 strings of 3 panels.
Sell the old one to offset the expense.

 

[guidecca]

I think you should upgrade your SCC so that you can do 2 strings of 3 panels.
Sell the old one to offset the expense.

And that would alleviate the voltage issue being too high for the solar charge controller? Have any recommendations?

 

[John Frum]

And that would alleviate the voltage issue being too high for the solar charge controller?

Yes.

Have any recommendations?

I will have a look.

 

[John Frum]

Maybe it would be better to find a 6 way combiner box.
This may work.

Tracer AN Series (50~100A) MPPT Charge Controller

EPEVER Tracer-AN adopts MPPT(Maximum Power Point Tracking)technology. This mppt solar charge controller capacity range from 50A to 100A.

www.epever.com

I'm not very knowledgeable for PV stuff

 

[guidecca]

Assuming you want to do 6p yes.
You should still have a double pole disconnect though.

Correct.

The you need to use 6 awg wire between the combiner box and the solar charge controller.
Also you can't do 6p with 63 amp breaker.
Is it a double pole breaker with sufficient voltage rating?

Here are the specification on the 63A circuit breaker

 

[guidecca]

Maybe it would be better to find a 6 way combiner box.
This may work.

Tracer AN Series (50~100A) MPPT Charge Controller

EPEVER Tracer-AN adopts MPPT(Maximum Power Point Tracking)technology. This mppt solar charge controller capacity range from 50A to 100A.

www.epever.com

I'm not very knowledgeable for PV stuff

Well, I know even less. You are a very kind person to spend this much time with an ignoramus.

 

[John Frum]

If you go higher than 50 amps with the scc then you need to go back to a main busbar topo.

Here are the specification on the 63A circuit breaker

Is it double pole?

 

[guidecca]

If you go higher than 50 amps with the scc then you need to go back to a main busbar topo.

Is it double pole?

Yes.

 

[guidecca]

If the object of a new SCC is to increase the PV voltage input capability I have yet to find a SCC with Max Solar Energy Input Voltage greaer than 150v. For example: MPPT Solar Charge Controller (48v 36v 24v 12v) Max Solar Energy Input Voltage: 250v

I can find a combiner box which you say will combine two strings in 2s3p. Is that correct? The voltage of the three panels in parallel would be 145.77v which is under the max solar energy input voltage of 150v. Why not use three 20a inline fuses on the positive panel wires and use two 3 to 1 MC4 connectors to combine all positives and combine all negatives. Is that all that is needed? Or will the SCC become another high dollar component.

 

[John Frum]

If the object of a new SCC is to increase the PV voltage input capability I have yet to find a SCC with Max Solar Energy Input Voltage greaer than 150v. For example: MPPT Solar Charge Controller (48v 36v 24v 12v) Max Solar Energy Input Voltage: 250v

250 volts is greater than 150.
I'm confused.

I can find a combiner box which you say will combine two strings in 2s3p. Is that correct?

Yes a combiner box that will support 2s3p would be fine.

The voltage of the three panels in parallel would be 145.77v which is under the max solar energy input voltage of 150v.

Not correct.
2s3p is 3 strings of 2 panels in series.
Short circuit current = 10.69 amps
Open circuit voltage = 48.69 volts
For each string the planning voltage will be 97.38 volts and the planning current will be 10.69 amps.
For the whole array the planning voltage will be 97.38 volts and the panning current will be 32.07 amps.

Each string should get a 20 amp overcurrent protection.
The wire from the combiner should no thinner than 8 awg with 50 amp overcurrent protection.
If the combiner box doesn't have a double pole disconnect or overcurrent protection for the wire between the combiner and the scc you need to use 6 awg wire to accomodate your 63 amp double pole breaker.

Why not use three 20a inline fuses on the positive panel wires

That would be fine.

and use two 3 to 1 MC4 connectors to combine all positives and combine all negatives.

The highest continous amperage I would put on the 3-1 connnectors and subsequent 10 awg wire is 24 amps.
You would be ~8 amps out of spec high.

Is that all that is needed?

I think you should find a combiner box.

Or will the SCC become another high dollar component.

Lets try to avoid that.

 

[John Frum]

I found this calculator on Explorist Life.

Solar Charge Controller Calculator

www.explorist.life

It recommends 3s2p with this solar charge controller

Victron SmartSolar MPPT 250|100

What is a Charge Controller? The purpose of a solar charge controller is to take power generated by a solar panel array and regulate the incoming voltage and amperage to a more appropriate level to

shop.explorist.life

And this wiring kit.

Victron SmartSolar MPPT 250|100 Wiring Kit

The Victron SmartSolar MPPT 250|100 Wiring Kit includes everything you need to connect a Victron SmartSolar MPPT 250|100 solar charge controller to a Victron Lynx Distributor (Victron Lynx Distributor and Victron SmartSolar MPPT 250|100 solar

shop.explorist.life

His topo drawing also shows this.

Solar Isolator Disconnect

This solar isolator disconnect is installed between the solar array and the charge controller to disconnect both the positive and negative conductors simultaneously. This disconnect is rated for solar arrays up to 63A and 1,000VDC.

shop.explorist.life

A 100 amp charge controller dictates doing a core busbars topology.

2490 watts is a lot of pv for a van.

 

[John Frum]

Hold the phone... is that 3 panels or 6 on your roof?

 

[guidecca]

This is an epic answer but you did not avoid all of my ignorant questions yet. LOL I bought two 3 to 1 MC4 connectors and that seems to be my default solution to all panel array issues. I used Midnight Solar's String Calculator; there a

Max Solar Energy Input

re only three solar panels.

 

[guidecca]

Just three panels. Its a 2007 Ford Econoline F-250. I had four panels on my first build on a different frame. Those were baby panels, 100w Renology. This past summer I had a guy build me an aluminum frame to fit the three Q-cell solar panels., 415w x 3 = 1245w total. I could never understand the 3s2p concept.

 

[John Frum]

Just three panels. Its a 2007 Ford Econoline F-250. I had four panels on my first build on a different frame. This past summer I had a guy build me an aluminum frame to fit the three Q-cell solar panels., 415w x 3 = 1245w total. I could never understand the 3s2p concept.

I have poor vision.

 

[MisterSandals]

I could never understand the 3s2p concept.

Here is a diagram (post #6) and discussion for whole thread.

3s2p

Can someone help me with a diagram of 3s2p for solar panels. All panels are 100w My set up is 12v system. Renogy Rover Li 40a CC. 1,000w pure sine wave inverter. Three 120 ah LifePO4 batteries wired in parallel.

diysolarforum.com

 

[John Frum]

Ok for 3s use this scc

Victron SmartSolar MPPT 250|60

What is a Charge Controller? The purpose of a solar charge controller is to take power generated by a solar panel array and regulate the incoming voltage and amperage to a more appropriate level to

shop.explorist.life

Will need to use core busbar topo.

 

[John Frum]

This is an epic answer but you did not avoid all of my ignorant questions yet. LOL I bought two 3 to 1 MC4 connectors and that seems to be my default solution to all panel array issues. I used Midnight Solar's String Calculator; there a


re only three solar panels.

What?

 

[guidecca]

I was just saying that I used Midnight Solar's string calculator. https://www.midnitesolar.com/sizingTool/ So, the 250/60 charge controller is pretty expensive; we are doing a shift from six to three panels (in series). If I spend over half a grand on a solar charge controller I will be able to wire three solar panels in series. Is that correct. There are no other alternatives? Recommend: https://www.amazon.com/gp/product/B07PZ6BB9Z/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1