Solar upgrade, wire splicing question

[Mikec557]

Greetings All

I am in the planning stages of upgrading my solar system. Those of you who have done solar know, it's a slippery slope. Presently we have three 100 watt Renogy panels wired in parallel. They in turn run through a Renogy PWM Adventurer Li 30 amp charge controller, which charges two mystery batteries given to us by the RV dealer. They are AGM group 24 "marine/rv batteries." I have no idea what their true amp hours are, but it doesn't matter because they are the first to get jettisoned.

I began with the thought of going cheap, as in keep all my present equipment and get two group 27 AGMs. Then the lithium bug bit me. (and we don't even use that much power) But you're in for a penny, in for a pound.

Now I'm thinking two battle born 100ah batteries, Victron MPPT Smart Solar 100v/50amp charge controller with built in Bluetooth (overkill for 3 panels but I'm trying to future proof) and the BMV712 battery monitor with Bluetooth. Also, I think I'm going to change out the WFCO to a Progress Dynamics lithium charger as well. I have been using a Traeger smoker (read: china) 400 watt modified sine wave inverter for my CPAP and figure it's time to upgrade to a true sine wave inverter. Wouldn't you know it? Another slippery slope.

So while I've been pondering the options and shopping the components, the Renogy Bluetooth dongle and/or charge controller has begun acting up. Charge controller seems to be working based on the display readings, but the Bluetooth reports egregiously wrong data. Such as historical data which says, I generate 65,535ah each day. I seem to remember that number from my Commodore 64 16bit computer days. Something is broken in one of the two of them. They're still under warranty and Renogy asks me to send in both so they can test them and replace the right component. Fair enough, but we full time. Looks like my solar upgrade project just got moved to the front burner.

Which leads me to the first of what will probably be many questions. In the hallway where the Renogy charge controller is (and which I am now going to bypass) I need to splice the cables coming from the rooftop solar panels to the cables running to the batteries in the battery bay (where the new charge controller will be located. They are 10ga and 8ga respectively.

1. What is the best way to splice these?

2. Given that my 3 panels have an optimum 5.7ah output each (17.1ah total), and given that the run length is about 3ft of 10ga and 10-12ft of 8ga, can I continue to use these wires, hooking them up to the MPPT Victron Smart Solar 100/50amp charge controller which I will place in the battery bay?

It is conceivable that I could replace the 8ga cable from the hallway to the battery bay. But the 10ga coming down through the ceiling is not easily replaceable, as in, that's too much work for only three panels. If I ever add more panels (which there is no room for), then I'll rework the rooftop and change to a combiner box etc.

What do you think about splicing and gage of wire?

Thanks
Mike

[gbkims]

I'd splice the wire 10 Awg to the 8 Awg. 10 Awg for solar pv typically good for 30A.
Several ways to splice, TBs, Butt/In-Line, Anderson Power Products SB50, MC4.
Depends on how you're going to place the wires once you've connected them together, like tuck them behind wall.
At my MPPT I'll have DIN rail TBs & DC CBs for the PV wires, then into the MPPT. Similar to my front compartment TBs shown below.

MC4 10 Awg Female to MC4 8 Awg Male
8-14 AWG Butt Splice Connector Kit
Dinkle Solar Combiner DK10N 10 Gang Box Connector DIN Rail Terminal Blocks, 6AWG, 60 Amp, 600V
MidNite Solar MNEAC30 > 30 AMP 120 VAC DIN Breaker

MC4 8 Awg

[Mikec557]

I'd splice the wire 10 Awg to the 8 Awg. 10 Awg for solar pv typically good for 30A.
Several ways to splice, TBs, Butt/In-Line, Anderson Power Products SB50, MC4.
Depends on how you're going to place the wires once you've connected them together, like tuck them behind wall.
At my MPPT I'll have DIN rail TBs & DC CBs for the PV wires, then into the MPPT. Similar to my front compartment TBs shown below.

MC4 10 Awg Female to MC4 8 Awg Male
8-14 AWG Butt Splice Connector Kit
Dinkle Solar Combiner DK10N 10 Gang Box Connector DIN Rail Terminal Blocks, 6AWG, 60 Amp, 600V
MidNite Solar MNEAC30 > 30 AMP 120 VAC DIN Breaker

MC4 8 Awg

Thanks GB
I was just reading about some big butt connectors 😮 on Amazon. I'll look up the products you mentioned. Never thought about mc4 connectors, I didn't realize they might accept wire of this size. My goal would be to let them dangle inside the wall cavity.

Mike

[Mikec557]

Here's an interesting product that shows potential. Though in the spirit of full disclosure I should note that the state of California says it could cause cancer and or birth defects...

https://www.homedepot.com/p/ASI-14-2...-307768519-_-N

Mike