Help with solar installation on Vegas 25.6

[GordonVoss]

Greetings,


I am in the final steps of putting 700 watts of solar on my Thor Vegas 25.6 and ran into an issue. The solar connectors on the roof do not connect to the charge controller wires...


This RV came "solar ready" (what a joke). The roof top solar connectors have a nice heavy gauge wire, but at the solar charge controller (SCC) it has very different wire only 10 gauge.



Does anyone know where these wires are connected (and down sized)?



The REAL problem is that there is no continuity from the roof top connectors to the SCC. I build (2) 20 foot solar cables, connected them to the roof top connectors and then dropped the wires down to the RV door so I could use a multi-meter to check continuity. No continuity on either side, + or -.



Does anyone have any idea how these wires are suppose to be connected?



Is there a fuse buried someplace that I may have tripped? But that still does not explain why I don't have continuity on the negative side that does not need a fuse.



Any suggestions on trouble shooting this are greatly appreciated.


Gordon

[TucsonAZ]

There is A LOT of missing and needed information here for me to answer this so somebody else may know more and better. But, solar is my thing and I'm well versed in it so I'll respond accordingly.


To me when I hear "Solar Ready" I hear under sized wire, possibly a PWM charge controller with a matching modified sine wave inverter of some sort to match. This would be fine for a 50 watt panel or battery maintainer type thing but not much else.



I would need to know way more specifics wise though, what sized panels, there's a HUGE difference between 7 100 watt panels and 2 350 watt panels. What configuration are you running them in so I know voltage going into the charge controller which helps us gauge wire sizing.



700 watts is great but you'd want a MPPT charge controller (EPEVER on the lower end is great) and a Pure Sine Wave inverter (Samlex or better ideally). Also, what is the sizing on your battery bank?

[DavidEM]

Well, I can describe how my Thor Axis 24.1 with a single factory installed 100 watt panel is installed:

The single panel is mounted to the roof and its cable runs to a solar port in back of it. I haven't opened up that port but I suspect it just has the incoming wires crimped to the 10 gauge wires that go down inside the coach.

The wires from there go across the roof (presumably) and down the wall to the solar controller mounted in the entry way. It is a 10A Go Power PWM controller. The output to the batteries is wired directly through a 10A fuse located right at the batteries.

If you are getting no continuity, + or -, I suspect the connections inside the solar port were never made. Open it up and look inside.

David

[TucsonAZ]

Originally Posted by DavidEM

Well, I can describe how my Thor Axis 24.1 with a single factory installed 100 watt panel is installed:

The single panel is mounted to the roof and its cable runs to a solar port in back of it. I haven't opened up that port but I suspect it just has the incoming wires crimped to the 10 gauge wires that go down inside the coach.

The wires from there go across the roof (presumably) and down the wall to the solar controller mounted in the entry way. It is a 10A Go Power PWM controller. The output to the batteries is wired directly through a 10A fuse located right at the batteries.

If you are getting no continuity, + or -, I suspect the connections inside the solar port were never made. Open it up and look inside.

David

This is sort of what I suspected, it's set up to maintain the coach batteries and not a 700 watt solar array with a small battery bank and PWM controller which is the equivalent of having a chimp sit with the 18v wire from the panels and tap it to the positive on the battery for a moment and then remove it...over and over all day long.



In theory, you could run the panels to increase the voltage to say 100V with an MPPT charge controller on the other end of those 10ga wires you'd be good up to 5amps, okay strike that I guess you'd need to be closer which some of the EPEVER will do and then you'd be fine. Better to honestly set it all up as a stand alone system though with all new wiring.



Good luck!

[GordonVoss]

Thanks to the Solar experts. DavidEM hit it on the head. I think something is not connected. Just don't know where.



For the great solar experts that what more information here is a write-up I did for a solar forum on my design:


Greetings,

I am new to this, but think I have a good design. I am curious if I missed something or over/under designed something.

I have a Thor Vegas that came “Solar ready”, which gave me a Go Power 10 amp Charge Controller (this one was removed), with 10 gauge wiring to the rooftop connection ports. Note the 10 gauge wire gives me a 30 amp limit from panels to charge controller… I know there are several options for panels, charge controllers… but I thought for my first design I would stick with a single vendor for most items. Hoping that means easy integrations and installation, then trouble shooting…

I am using (4) Renogy 175 watt flexible panels (175W, 9.5A, 23.9V). So I can use the 10 gauge wire, 2 panels are wired in Series (giving: 350W, 9.5A 47.8V). The positive side of these 2 panels in Series has an inline 15A fuse.

The 2 sets of panels wired in series are then connected in parallel with 2 to 1 Solar Branch Connectors that will connect to the existing roof top connection port. The 10 gauge wire can handle the load (Giving: 700 Watts, 19A, 47.8V). So this is well within the 30 amp limit of the 10 gauge wire.

In the rig, the wires come into the new Renogy’s Rover 60 Amp MPPT Solar Charge Controller, with bluetooth option. The positive outbound side to the battery bank has a 70 Amp ANL fuse on it and use 6 AWG wire to the batteries.

The batteries are Renogy 12V 100Ah Smart Lithium Iron Phosphate battery w/Self-Heating Function (RBT100LFP12SH-US). 2 wired in parallel with a communication port that will self balance the batteries via the Battery Management System. I have the battery monitor that connects directly to the BMS of the batteries. No shunt needed.

At this point I did not install an inverter. I did replace the converter that came with the RV with one that supports my new lithium batteries.


The converter and batteries are working fine (as of this last weekend when I forced the converter into lithium mode). I installed the panels on the roof yesterday and this is when I discovered that the MC4 ports on the roof do not connect to the wires that came out of the original Solar Charge Controller (SCC).



This is the problem, no continuity from the MC4 connector on the roof to the original wires that connected to the now replaced SCC.



I fully understand and respect those that wanted to make sure I knew the limitations of the original wiring and SCC. Dealing with wire limitation and replaced the SCC.

[TucsonAZ]

Originally Posted by GordonVoss

Thanks to the Solar experts. DavidEM hit it on the head. I think something is not connected. Just don't know where.



For the great solar experts that what more information here is a write-up I did for a solar forum on my design:


Clipped

I was incorrect on the amps, sorry for that, I was not paying attention. I tend to over do it on wiring in general and only run at half capacity for pretty much everything. The 10ga wire is likely for what you have going on.


I'm shooting from the hip here but I would try to use breakers versus fuses from the solar panels to the CC, they really just serve as an ability to shut the power off. I also always try to go with the higher input voltage I can. The down side to that is if you shade a single panel it impacts output on them all so what you're doing by doubling them up seems good.



Can you add MC4 connections to the wires in the junction box on your roof? Did you test all of the connections with your panels up top, are you getting proper voltage?



I don't have a ton more I can add, the system will work fine for you. You may want to look into a hybrid inverter which can charge batteries, work as a MPPT charge controller, handle the 120v coming into the unit and be your inverter.

[GordonVoss]

Update: I pulled off the solar port on the roof to find that the connection was solid, but to the wrong side of the wires. They ran wires (color coded) from the SCC up to the roof at the edge by the bathroom, then across the roof in a cable tray all the way to somewhere???? on the other side of the rig. I have no idea where they may go. They cut a hole to the cable tray and then spliced the correct cable, but connected it to the wrong side of the wire. Simply amazing.

[Dirny]

Originally Posted by GordonVoss

Update: I pulled off the solar port on the roof to find that the connection was solid, but to the wrong side of the wires. They ran wires (color coded) from the SCC up to the roof at the edge by the bathroom, then across the roof in a cable tray all the way to somewhere???? on the other side of the rig. I have no idea where they may go. They cut a hole to the cable tray and then spliced the correct cable, but connected it to the wrong side of the wire. Simply amazing.

Hi Gordon

I have a 2019 Axis 25.6 that I am trying to add solar to and cannot for the life of me find my "solar port" on the roof. Could you please tell me where yours was located? I think it should be obvious, but maybe they just didn't install it at the factory.

Thanks,
David

[GordonVoss]

David,


It is obvious, so maybe your rig was not setup "solar ready". We bought ours used, so don't know if this is a standard setup or was ordered on this rig. Mine was located just to the passenger side of the vent over the bed. Centered (left to right) in the roof. I also had a SMALL (100 watt) Solar Charge Controller right at the steps going into the rig. So if you don't have a SCC at the steps, I am guessing that you don't have a solar ready rig.



This may be a blessing since the "solar ready" wiring was so small it limits how you can connect your panels.



There is a lot of information out there on how to run your own wiring down into the rig.



Good luck.


Gordon

[Dirny]

Originally Posted by GordonVoss

David,


It is obvious, so maybe your rig was not setup "solar ready". We bought ours used, so don't know if this is a standard setup or was ordered on this rig. Mine was located just to the passenger side of the vent over the bed. Centered (left to right) in the roof. I also had a SMALL (100 watt) Solar Charge Controller right at the steps going into the rig. So if you don't have a SCC at the steps, I am guessing that you don't have a solar ready rig.



This may be a blessing since the "solar ready" wiring was so small it limits how you can connect your panels.




There is a lot of information out there on how to run your own wiring down into the rig.



Good luck.


Gordon

Thanks Gordon. I have the SCC and the wires running up toward the roof. What I don’t have is the connection point. Thor must have screwed up (shocked!) and never put it on my roof. Must be why they are not getting back to me about where it is. I’ll just run a separate line in… getting another controller anyways.

[GordonVoss]

David,


On my rig the wires ran in a metal cable tray (~2 inches wide) that ran from the bathroom area (just on the other side of the pantry and in the medicine cabinet) to the vent over the bed. It appeared to run strait across, not at an angle. I am guessing that you can find the wires if you take out the vent and see what wires are running over there. You should be able to do a continuity test back to the SCC to verify you found you wires. I think they ran solar and fan wires in the same cable tray and then just knew where on the roof to drill the hole to hit the cable tray, then splice into the wires. That is want it looked like when I pulled the port off.



I hope you find them. Just make sure you check the gauge of wire and design your panel connections not to overload the wire. That is what I had to do.


Good Luck
Gordon

[Dirny]

That’s very helpful information, and really narrows down where I need to look. Thank you so much!

I’ll for sure be looking out for the gauge of the wire, but I’m only having a single 200w panel installed and Thor “says” the wire should be 10 gauge.

Really appreciate your detailed response. I’m on the hunt!

David

[Dirny]

Well, going on your excellent directions, I unfortunately found my solar wires that were supposed to be going through to the roof. I pulled down the trim for the rear fan, a lo and behold there were the solar wires, cut off and just sitting there.

Not sure what to do with them at this point, but I will leave that decision up to my installer. Don’t know if they are going to be of any use.

Thanks again for all your help…. Couldn’t have found them without it.

David

[153stars]

By eye those wires look pretty small probably okay for 100-200 watts of panel unless running several in series raising the voltage . That gives you more of chance for shading loss.
Using the fridge cabinet and vent curb is popular way to chase wires. Other cabinet arrangements ceiling to floor like pantry,closet or washer dryer might work well also.
Keep us up dated on your install.