Solar Problem

LTVs does do a solar pre-wire on all Unity's. Their solar pre-wire consists of a #8 awg wire pair from the over door compartment to the battery box only. No down wires from roof to over door cabinet. Read the posts I provided and you'll get the details. 8 awg wire size would support 400w fine. I installed 200w to start and then it's easy to add 2 more 100w panel down the road if I decide I need it. Installing a complete system, with a 100v/30a MPPT controller, battery monitor, and 1 or 2- 100w solar panel(s) is the hardest part, then expanding in the future by adding panels is easy.

I asked them to prewire for me even though I did not order the solar from them. They did so. They will probably do that for you as well. What that means is there will be wire on the roof to the storage bay where they would normally install the charge controller. And then there will be wire from the storage bay to the battery bay. Two different wire types but both #8 which is fine. When you do your install you will butt connect those wires in the storage bay and wire your charge controller in the inverter bay. At least that's how I would do it.

I'll be in Show Low next summer. Drop by and we'll do this thing! Or SSTraveler will help you in South Carolina! Finding someone to do this for you will be difficult and they probably won't do as good a job as you will do!

2yrs2go said:

I just ordered a new 2019 Unity MB and made the mistake of ordering with the 4 solar panels installed. After reviewing this forum and talking to others at the Hershey RV show, I see it best that I cancel the factory solar installation and have the Solar installed after delivery. I already talked to one vendor at Hershey and am looking to get other quotes, but the Unity will not be delivered until next June so I have time to study and learn. Any recommendations will be happily accepted. And Klipstr and SStraveler I have already marked your messages to start the process, so thanks.
One question, not sure if it was on this forum or someplace else, but does LTV prewire all their RV's for solar even if the factory option is not ordered?

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I don't know why LTV wouldn't do the down wire from the roof as part of the pre-wire. They do it for the satellite pre-wire and stub it on the roof why not the same treatment for the solar pre-wire. In fact they should just do one continuous run from the roof, through the over door compartment, to the battery box of a #8 wire pair and leave it stubbed under the roof's GPS antenna plate. If you have LTV run the roof down wire as part of your solar pre-wire then it will make your installation a lot easier and cleaner. Absolutely, I'd be glad to help anyone just send me a private message and well get on with it. Now that I've done the install I realize it's really not hard, just labor. Assembling all the pieces parts for the install is time consuming but worth it to have everything on hand before you start. Try not to do the install in the summer if you can help it. I could only work about 3 hours a day because of the heat. That forced me to do it in sections and slower, giving me down time to think the various parts of the install through. I think I did a better install, taking more time.

Or pull the rig into your big a-- garage and work in there!

TwoClinks said:

At this time, it looks like GP is going to send one new soft panel. The tech is stating that peeling does not effect the output. ??? I only have to submit proof of purchase along with my shipping address. After some good advice here, I am going to take both soft panels off and install two 100w. Renogy panels now and two more later. Keep you posted.

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TwoClinks, I am curious what your resolution with GP was because I just discovered I have a similar issue with one of my panels. What is the telephone number and contact person at GP for warranty issues? One of my panels is delaminating.

Warranty is 5 years n them. Had the same problem and were replaced by LTV.
If I had to do it again, I would leave them on an replace them with "Renogy" brand.....

I’m sorry but I couldn’t tolerate 8 AWG from the controller to the batteries let alone down from the roof for 400 watts of parallel connected solar panels. That’s pissing away too much juice for me, perhaps Handy Bob as well.

Hi Tanny's,


Sorry this thread has been hijacked from solar problems to aftermarket solar upgrades. It really screws up the archives when someone is looking for a solution to their problems.


You can contact Go Power on their website or call the support team @ (1-866-247-6527). I suspect they know they have a problem with their soft panels however they denied heat failures and low performance from delamination. Keep in mind that GP panels are Canadian and so is LTV where the summer season is short. My 2016 has had the full harsh weather exposure of Texas. They sent me one new replacement panel for the soft panel that had failed. However as others have said, the best, long term solution is to replace and expand your system with hard panels and find affordable covered storage as I did this week.

jackfish said:

I’m sorry but I couldn’t tolerate 8 AWG from the controller to the batteries let alone down from the roof for 400 watts of parallel connected solar panels. That’s pissing away too much juice for me, perhaps Handy Bob as well.

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TwoClinks, sorry to further hijack the thread (you are correct!) but,

No, not really. Especially if you upgrade the controller and run the panels in a series parallel configuration.

If you put the numbers into a voltage drop calculator here:

https://www.calculator.net/voltage-drop-calculator.html

I used #8, 17V (panel nominal), 20', 30A. Drops the voltage to 16.25V or 4.43%. At 16.25V at the charge controller next to the batteries (rather than in the overhead bin) you will charge the batteries quite nicely. And as the current drops do so does the voltage loss so at the end of the charge cycle you will be seeing even more than 16.25V.

You can play around with various wire sizes. At #6 for instance (probably the only reasonable change to make as #4 would be hard to run!) your drop is to 16.53V. For 1/4V? I don't think so.

And in real life, early in the charging cycle, you won't use 16V anyway. And as you get late in the cycle amps are less so drop is less and you are good to go.

If you go to a series/parallel and better controller your voltage doubles and your loss with the existing #8 drops from the 34V nominal to 33.62V. That's next to nothing.

Worrying about wire size is important. But keeping it in reasonable perspective is equally important. IMHO opinion of course. I've worked through all of this with Handy Bob over a couple of beers in MT.

Sorry again, David.

I did a whole, whole lot of reading before doing my own solar install, including Handy Bob, who is not fond of MPPT or lithium. I also talked with pro installers affiliated with AM Solar and other independent installers. In their proposed system plans, they recommended minimizing voltage loss from panels down to the batteries. 4 AWG was the most common recommended wire size. As long as you get wire with a high strand count, it is very flexible, not hard to run, and marginally more expensive. I don't see how it would be any different to run than 6 AWG. I ended up not going with any of these installers due to markups in equipment cost and very high labor costs.
I used 8 AWG PV cable from WindyNation from panels to the combiner box, then 4 AWG cable down from the roof. I had to clip a few strands of wire to get the cable to fit into the Victron 100/50 connectors. I could have butt-spliced a short segment of 6 AWG, but didn't. My voltage drop is < 1%. We wanted a system that would have top solar collection and charging, as we camp away from hookups most often.

I see a lot of people installing MPPT controllers while keeping parallel panel wiring. In this setting, voltage loss is even more important. The Victron controllers won't even turn on until a certain voltage is reached, so charging earlier in the day can be compromised, especially if the sun is not the greatest.

From the manual:
"● The controller will operate only if the PV voltage exceeds battery voltage (Vbat).
● PV voltage must exceed Vbat + 5V for the controller to start. Thereafter minimum PV voltage is Vbat + 1V".

If you have lithium batteries, this is even more important due to the higher resting voltage of lithium banks.

I agree that series/parallel pairs are the way to go, though I wasn't sure initially. And I do believe that LTV's solar pre-wire is not adequate, especially when they ship their units with the GoPower PWM controller and panels wired in parallel. Changing to a MPPT controller and series/parallel wiring obviates some against this design choice. So many folks relate that they get rather low charging amps from their stock setups and I think the above is why.

TwoClinks said:

........the best, long term solution is to replace and expand your system with hard panels and find affordable covered storage as I did this week.

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TwoClinks is giving you the best advice. Replace your flex panels with Monocrystalline rigid glass panels. You can install them over your old panels, leaving the old ones abandoned in place. Or rip off the old and replace with new. You'll have much better solar collectors and the Renogy glass panels have a 25 year warranty. You'll never have to worry about them again. There are lots of threads with install experience, it's a DIY job, you can totally do yourself! Do some research first, https://sprinter-source.com/forum/search.php?searchid=3737231, to decide how you want to mount the panels.