Another Solar Panel Install Question

I have a 2018 Unity MB that's been pre-wired for solar and I've traced the solar wires from behind the system monitor panel over the entry door to behind the right panel in the passenger side overhead locker and then down to the battery compartment (I haven't determined yet if they are already connected to the batteries). I live in Florida and I'm looking for a simple solar solution to keep the coach batteries topped up while the Unity is in storage (would the solar panel also charge the chassis battery?). The kit that I'm considering is the Renogy 200 Watt 12 Volt Flexible Solar RV Kit. Installation steps seem pretty straight forward: install the panels on the roof and connect the wires; punch through the roof and connect to the pre-installed wires behind the system monitor panel; cut the pre-installed solar wires in the overhead locker so that one end is coming from the panels and the other end goes down to the batteries. Installing a 30 amp fuse somewhere in there would also be good. My question is: the pre-installed solar wire bundle contains a third wire labeled 'Solar Bonding Wire'...where would this be used in my configuration? Also, any general opinions/recommendations on my general approach. Anything to watch out for? Much appreciate your help. Thanks.

The third wire is from when LTV installed rigid panels and bonded the frames. They kept it in their harness but it is no longer used.

Don't cut the wires in the overhead locker unless you plan to add a charge controller there (inadvisable). That is a loop for the cc. If you cut it you'll break continuity from over the entry door to the batteries.

Behind the batteries you'll find a fuse holder connected to the positive buss bar. That's the termination of the solar pre-install. The fuse holder is empty. The negative preinstall termination is also already connected.

If you search the forum you'll find a number of write-ups with pictures. Different people have taken different approaches. Here's mine.

I'll ignore the bonding wire then, thanks.

I was planning on putting the charge controller in that upper locker (since that's where LTV would have install it) hence cutting the pre-installed solar wires but I've read elsewhere and your installation places it in the space with the inverter. Let me rethink the location for the cc since that would also allow for a more convenient location for a 30 amp fuse. Thanks for your help.

There are others on here who can explain it far better than I, but the short explanation is you want the charge controller to be as close to the battery bank as practical to reduce loss.

I would not place a 30 amp fuse in the pre-install fuse holder. The fuse wire gauge is pretty small. See my write up to see why it's smaller than what's coming down from the roof. If you don't want to enlarge that wire, you don't need a 30 amp fuse for 200 watts.

You may find that at some point you would like more wattage on the roof. I would plan your wire size, charge controller type and location with that in mind.

If possible stay away from flex panels, they just don’t age well. They have 5 year warranty, ridged 20 year warranty.
Read up on AM Solar, they won’t install flex.
Many people have installed ridged panels by gluing down, search here.
Your roof already has many holes, few more?
You know that it is better to use a MPPT charge controller? What is in that kit?
They also have ridged kit, lower at Amazon!

I agree, flex panels are NOT the way to proceed.

I used these: Renogy Black Frame Panels
Currently priced at $109.99 each

and a Victron 100/30 Controller (Victron Controller
226.10 each

Then there are odds and ends (mounts, cable, connectors, etc.) and would be better than flex panels. They heat up the roof/coach, degrade faster and overall lessor quality than rigid panels.

Check out my Solar install thread for mounting ideas. Solar Install

A Victron BMV-712 is a nice addition to the system too. Victron BMV-712

I just looked at a Renogy 200 watt kit (https://www.renogy.com/200-watt-solar-flexible-kit/

It comes with a 20A PWM and 10 AWG wire.

A MPPT controller would be better and if you ever upgrade to 400 watts, you'll have to swap out the 20A PWM for something else. The kit is $549.99

With my links above, you could have 2 rigid frames and a controller that would allow you to upgrade later to 400 watts for about $447 excluding mounts, cable (I'd go with 6 AWG welding cable as it is VERY flexible - 8 AWG Welding cable minimum), connectors, etc. Link to wire here: 6 AWG welding cable

And for 2020, there is a 26% solar tax credit which applies to homes including second homes (which is the RV). This tax credit is subtracted from tax owed. May be worthwhile to just initially install 400 watts.

Solar Tax Credit

Thanks all for the info. It's now back to the planning stage. I initially selected the flex panels since that was what LTV installed and also for appearance i.e., can't be seen from ground level so gives a cleaner line to the top of the vehicle. However, given all the other stuff on the roof, a couple of solar panels won't distract all that much. Also, it seems that the MPPT controller is the way to go over the PWM and install it in the inverter compartment. The Solar Tax Credit is an interesting benefit/excuse to increase the number of panels. Thanks for that.

MSMOLOW: I'm assuming that the 12v switch that you installed is between the panels and the controller and not between the controller and the batteries. I was looking at the 30 amp fuse mentioned above really as a place to disconnect the panels from the controller but the 12v switch is a better solution. That way you can get the entire system connected up and supply power to the controller before you switch in the solar panels. Great idea. I would like to see something like that for the chassis battery so I won't have to pull the cable off the peg for storage. Also, it looks like you tapped into the wiring harness for the solar wires before they went into the battery compartment (obviously removing the bitter ends that were connected to the batteries), correct?

Thanks again and I'll post results shortly...since we're now on house arrest (thanks COVID19) and have plenty of time for projects like this.

Correct on the switch. The panels need to be disconnected from the charge controller before you disconnect the battery or you risk damaging the cc.
Correct on the wire. I pulled both + and - from the battery compartment cut off the smaller wire added butt connectors and ran appropriately sized wire to the inverter compartment. The down harness is easily accessible before it enters into the battery compartment.

Okay, after looking at the hard panels, any reason not to get a pair of the 200w panels (i.e., Rich Solar 200 Watt panels)?

The size of the Rich Solar 200 Watt panels may be too large for space available on the roof. You can space out 4 of the 100 W panels. And remember that you may need walking (stepping) space around the panels and what is already on the roof.

I would put a 30A circuit breaker between the batteries and the CC and another one between the CC and the solar panels. A short or catastrophic failure of the CC could allow the battery current to back feed and the 6 AWG wiring would melt and potentially cause a fire. 30A Circuit Breaker

Putting the CC in the inverter bay would allow for connecting the CC to the Inverter instead of running wires back to the battery. The inverter is already wired to the battery.

And here is a sign you can put in the inverter compartment and in the battery compartment as a reminder.

Well, you are correct. I measured the open areas on the roof today and the only panels that will fit are the 100 watt. So be it. I'll probably start with two panels and see what that gives me. Once the base system is in place, I could always add a couple of new panels if I need them. Thanks again for all your help.

Search for posts by either me or SStraveler or DiverBob on this topic. That will give you the basics you need to do a great install on your rig. Many others have weighed in with great advice in the posts you will find. Everything already stated in this thread has been covered elsewhere in great detail so doesn't/shouldn't be done again.

I ain't dinging anyone for starting a new thread. Just trying to point you in the right direction so you get this done right!

Too bad Florida is so far from Show Low AZ. I'd have you come here and we'd do it. At a socially acceptable distance mind you (but FL to AZ is a bit too distant!)