MC4 Higher than 40a???

[rafrojack]

you can go half way,
2 in series each and those two in parallel. So you are running only 20A

You don't need a combiner box just a regular 2- > 1 MC4 adapter

Yup a series-parallel set up is the easiest route so far. I just don't like shading/damaged cells issue.

 

[rafrojack]

where do you put the combiner box?

Next to the panels on the roof. Just get a waterproof box with a twist cable entry like on a roof gland.

 

[ghostwriter66]

Dump the MC4 and go with ANDERSON CONNECTORS ...

 

[rafrojack]

How many feet between your panels and SCC?
What do you think are the advantages of parallel connecting?
How about connecting 2S2P for a lower 20 amps and higher voltage so you can run smaller cable?

20' there & back.
Advantages are no issues with shading/damaged cells interrupting flow.
I'm leaning towards the 2S2P method now. My buddy will just have to avoid shading & if there's a significant drop (while not under shade) to check the panels for defects.

 

[rafrojack]

More than two panels in parallel have to be fused individually. Just think of 30A going into that one panel with shorted bypass diodes.

Please explain. I don't understand how 3 would need individual but 2 is ok.

 

[rafrojack]

Dump the MC4 and go with ANDERSON CONNECTORS ...

They're not..waterproof..? Also, the waterproof one's with a boot is only rated for 30a.

Moisture Proof Splash Boot for Powerpole Connectors

Moisture proof your outdoor or automotive connections. The Splash Boot holds 2 sets of Powerpole connectors in mating male and female rubber boots. The wire input strain reliefs can be trimmed to accommodate various gauges of wire and ensure a tight seal.

powerwerx.com

 

[chrisski]

Ahh. To be clear you're going from 36VDC from 12VDC is not affecting your system? Your MPPT will step it down to the correct 12v settings for charging, correct? Or are you running a pure 36VDC system with a converter for 12vdc loads?

I measured the actual short circuit voltage from the three 12 volt panels in series and it was 48 VDC with 10 gauge wire, and once the charge controller is hooked up, the charge controller steps it down to the charging voltage between 12 and 15. At the charge controller I will have about three feet of 6 gauge wire from the charge controller to the batteries.

I was originally thinking 6 panels in parallel, but I came up with thicker wire like 8 gauge. After putting them in series, I ran the panels longer and used 10 Gauge wire.

The MPPT charge controller I have is 100 volts 50 amps, so that means I can't exceed an input of 100 volts and 50 amps, and it will step it down to a 12 Volt battery bank or a 24 volt battery bank, settable to my choice. As it steps it down though, it can't push to the batteries more than 50 amps. You could take all four of your panels run them in series into this charge controller to charge a 12 Volt battery bank and stay at 10 gauge wiring.

I don't use crimp tools for MC4 :D

I've crimped a lot of things like pins and BNC cables, and found the MC4 Connectors harder. My other two crimping tools would not work on the MC4 cables.

Dump the MC4 and go with ANDERSON CONNECTORS ...

Not sure Anderson Connectors are a good idea for a permanent setup. If I'm wrong, I'd like to know.

The MC4 cables have an IP67 rating, which is good waterproof wize. The Anderson Cables I picked up don't look like they would last out in the open long term, they just aren't sealed good. I may use Anderson plugs as my next upgrade for my trailer where I may tie in two or three ground panels, which would only be plugged in a few days, not yeats on end. The Anderson cables are easy to make and can be purchased in high enough amp ratings, I just don't know how they'd do outside year after year. It is supposed to be the go to thing for vehicles to plug in things like spotlights and other things with a quick disconnect.

Edit: I see you posted the splash proof Anderson Plugs. There's a difference between a "splash Proof" description and an IP67 rating https://www.l-com.com/frequently-as...le-connectors-or-adapters-what-does-ip67-mean

 

[ghostwriter66]

They're not..waterproof..? Also, the waterproof one's with a boot is only rated for 30a.

Moisture Proof Splash Boot for Powerpole Connectors

Moisture proof your outdoor or automotive connections. The Splash Boot holds 2 sets of Powerpole connectors in mating male and female rubber boots. The wire input strain reliefs can be trimmed to accommodate various gauges of wire and ensure a tight seal.

powerwerx.com

We use 45A Anderson connectors and wrap them in this -- https://www.amazon.com/dp/B08B3JSJF...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

 

[ghostwriter66]

Not sure Anderson Connectors are a good idea for a permanent setup. If I'm wrong, I'd like to know.

We use 45A Anderson connectors and wrap them in this -- https://www.amazon.com/dp/B08B3JSJF...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl -- not sure WHAT IP{ protection level it actually makes them BUT they have NEVER leaked or got water damaged or corroded ...

 

[Ampster]

How would what I'm powering come into play?

The panels power a charge controller or inverter. Different inverters or charge controllers take different inputs. Mine takes up to 600 volts so I don't parallel.

 

[rafrojack]

I measured the actual short circuit voltage from the three 12 volt panels in series and it was 48 VDC with 10 gauge wire, and once the charge controller is hooked up, the charge controller steps it down to the charging voltage between 12 and 15. At the charge controller I will have about three feet of 6 gauge wire from the charge controller to the batteries.

I was originally thinking 6 panels in parallel, but I came up with thicker wire like 8 gauge. After putting them in series, I ran the panels longer and used 10 Gauge wire.

The MPPT charge controller I have is 100 volts 50 amps, so that means I can't exceed an input of 100 volts and 50 amps, and it will step it down to a 12 Volt battery bank or a 24 volt battery bank, settable to my choice. As it steps it down though, it can't push to the batteries more than 50 amps. You could take all four of your panels run them in series into this charge controller to charge a 12 Volt battery bank and stay at 10 gauge wiring.



I've crimped a lot of things like pins and BNC cables, and found the MC4 Connectors harder. My other two crimping tools would not work on the MC4 cables.



Not sure Anderson Connectors are a good idea for a permanent setup. If I'm wrong, I'd like to know.

The MC4 cables have an IP67 rating, which is good waterproof wize. The Anderson Cables I picked up don't look like they would last out in the open long term, they just aren't sealed good. I may use Anderson plugs as my next upgrade for my trailer where I may tie in two or three ground panels, which would only be plugged in a few days, not yeats on end. The Anderson cables are easy to make and can be purchased in high enough amp ratings, I just don't know how they'd do outside year after year. It is supposed to be the go to thing for vehicles to plug in things like spotlights and other things with a quick disconnect.

Edit: I see you posted the splash proof Anderson Plugs. There's a difference between a "splash Proof" description and an IP67 rating https://www.l-com.com/frequently-as...le-connectors-or-adapters-what-does-ip67-mean

Decided to do a 2S2P set up.

I use pliers for my MC4 connectors, really easy.

Yup Anderson is still a no for me atm.

 

[rafrojack]

The panels power a charge controller or inverter. Different inverters or charge controllers take different inputs. Mine takes up to 600 volts so I don't parallel.

Yup, doing a 2S2P set up.

 

[rafrojack]

We use 45A Anderson connectors and wrap them in this -- https://www.amazon.com/dp/B08B3JSJF...uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl -- not sure WHAT IP{ protection level it actually makes them BUT they have NEVER leaked or got water damaged or corroded ...

This is "cherry tape", I used this daily doing electrical work on fighter jets. I've seen tons of water get into these. They can loosen over time & are just dangling annoyances. Good luck!

 

[Freddmc]

To me designing a system in a vehicle(RV) so as to use thinner gauge wire because it is cheaper doesn't make sense. The runs are generally so short the difference is insignificant.
..

 

[chrisski]

To me designing a system in a vehicle(RV) so as to use thinner gauge wire because it is cheaper doesn't make sense. The runs are generally so short the difference is insignificant.

Could be me wanting as close to 1% loss as possible, but it made a difference between 8 Gauge and 10 Gauge. Probably only saved a few dollars on wires, but I would have got the 8 Gauge MC4 crimpers and that would up the price.

This is "cherry tape", I used this daily doing electrical work on fighter jets. I've seen tons of water get into these. They can loosen over time & are just dangling annoyances.

I’ve got an avionics background also, and I thought the same thing.

 

[rafrojack]

To me designing a system in a vehicle(RV) so as to use thinner gauge wire because it is cheaper doesn't make sense. The runs are generally so short the difference is insignificant.
..

Not really when it comes to the PV -> MPPT portion & variants of amperage. Don't forget to use actual charts & out & back lengths.

 

[efficientPV]

example: One solar panel can produce 10A. With two in parallel one shorting and the other sourcing 10A, the shorted panel can only see 10A. With three in parallel two panels can produce 20A. That exceeds what a shorted panel can take. In many places this is code.

 

[tazmann]

I didn't trust the rubber o rings to last on the MC4 connectors so i cut them off and did a solder connection with marine heat shrink with couple wraps of electrical tape

 

[tazmann]

example: One solar panel can produce 10A. With two in parallel one shorting and the other sourcing 10A, the shorted panel can only see 10A. With three in parallel two panels can produce 20A. That exceeds what a shorted panel can take. In many places this is code.

So in that case would a fuse on each panel take care of that problem ? At the moment I am running 2S 2P each 2S run into fuse block with 15 amp fuse, planning on adding another 2S on the roof and another 2S portable so I will end up with 2S 4P

 

[Supervstech]

I didn't trust the rubber o rings to last on the MC4 connectors so i cut them off and did a solder connection with marine heat shrink with couple wraps of electrical tape

Kinda defeats the disconnecting purpose though...