Solar System: design/install

[oceanstater]

I'm planning out a basic solar install on my 2007 Fleetwood Utah and wanted to get some feedback from members who know the ins and outs of solar/wiring/efficiency, etc. I currently have a 100Ah 12V LifePo battery on order to replace my very heavy and not terribly efficient group 31 lead acid battery. I want to place a 100W (maybe two) fixed panel(s) on the rear end of the roof. I know this may not be the most efficient place to put panels but I have a friend who has a couple of extra panels laying around that he is willing to give me so I figured I may as well put them up there.

(I have included some pics where I have sketched in the planned wiring)

I would prefer not to drill any holes in a roof that currently has no holes and no leaks so I plan to run the wires from the panels along the roof rail channel, off the back corner, and drill a hole in the side of the roof where there are already wires feeding the interior overhead lights (pic 1). The wires can then run in the same canvas sleeve (pic 2) that leads down into the camper (pic 3) and into the compartment that houses the electrical panel (pics 4 and 5). I figured I would install the solar charge controller here since that is an access door I never use.

The question now is would I run new wires from the charge controller to the battery on the tongue? Or can I tap into the existing wiring (pic 6) that already runs from this cabinet to the battery box on the tongue? Or is there some other way the charge controller should be wired into this set up? Lastly, since the new LifePo battery is sealed should I consider moving it inside and off the tongue as I have read other people have done?

As an add-on down the road I may want to add a solar suitcase set up for when we are camping in the shade but that may just be something I alligator clamp onto the battery for supplemental power.

Thanks for your input.

 

[Grandpa Don]

I added solar to my Viking right after I purchased it 3 and a half years ago. I'm using a single 100 Watt panel. I did not permanently mount my panel on top. I store it inside of my camper when not in use. The factory wire from the camper to the panel is 20 feet long, but I can add a removable extension to move the panel farther out to find more sun. That way I can park the camper under the shade of some trees. My controller is mounted inside of the camper in an area that is out of the way. For wiring, I ran separate wires from the panel to the controller, and separate wires from the controller to the battery. I can't remember what gauge wire it is, maybe 10 gauge. I got the whole setup as a kit from Renogy. It has all been working just fine.

 

[Jwwiff]

I have an ‘07 Bayside which is basically the same setup as yours. I mounted 2 - 100W solar panels on top using the aluminum rails on the sides/corners of the roof and went across with 1” extrusions and mounted the solar panels to them. The are wired in series and the wiring goes to the back end of the camper and terminates with an Anderson connector. 10ga wiring was used to wire them together. I put an extra “mouse hole” like you already have for your shore wiring and ran the wiring from the charge controller, through the mouse hole to the solar panel Anderson connector. When down, I tuck the wiring back into the bench area of the camper.

I ran the panels from the MPPT controller to a bus bar which “t”ed into the battery and the current WFCO Power converter. I could do this as my controller is set up to charge standard FLA batteries. The MPPT and WFCO won’t fight each other when charging as each will sense the voltage and do what it does best. Since I am not running an Inverter off the 12VDC, I am not worried about the gauge of wiring from the battery to the rest of the system.

Phase II when I get around to it will be to change out the FLA for a Li of some type - 100A min. I have a second battery box already set up on the tongue. At that time I would upsize the wiring from the MPPT to the bus bar, disconnect the WFCO as it won’t charge the Li type of batteries, and drop in an Inverter for off grid operation. I have a big enough MPPT to also do a portable set of solar cells since the top of the camper is not ideal unless you are camping in the desert.

 

[oceanstater]

Thanks for the details. Jwwif, I understand having the MPPT wires going to the battery but why to the WFCO? Doesn't the WFCO just draw from the battery anyway?

 

[TSQ]

I'm planning out a basic solar install on my 2007 Fleetwood Utah and wanted to get some feedback from members who know the ins and outs of solar/wiring/efficiency, etc. I currently have a 100Ah 12V LifePo battery on order to replace my very heavy and not terribly efficient group 31 lead acid battery. I want to place a 100W (maybe two) fixed panel(s) on the rear end of the roof. I know this may not be the most efficient place to put panels but I have a friend who has a couple of extra panels laying around that he is willing to give me so I figured I may as well put them up there.

I've got a thread going over in the "Power - Site Power/Batteries/Generators/Solar" forum if you have not seen it already: https://www.popupportal.com/threads/new-electrical-system-build-thread-lithium-solar.134726/. My single 100W panel mounted flat on the roof gives me between 5Ah/day (totally shaded) to 50Ah/day (full sun @~45° North) in the summer.

Have you done a load analysis? Do you know approximately what your daily consumption is?

I would prefer not to drill any holes in a roof that currently has no holes and no leaks so I plan to run the wires from the panels along the roof rail channel, off the back corner, and drill a hole in the side of the roof where there are already wires feeding the interior overhead lights (pic 1). The wires can then run in the same canvas sleeve (pic 2) that leads down into the camper (pic 3) and into the compartment that houses the electrical panel (pics 4 and 5). I figured I would install the solar charge controller here since that is an access door I never use.

Originally I was relunctant to drill holes in my roof but in the end I just went for it: https://www.popupportal.com/threads/my-new-roof-rack.75985/page-2#post-1422557. No regrets so far but we will see how it works out after ten years. I hole-sawed a 1" hole in the roof and used a solar panel cable entry thingy. The wires come out under some trim in the inside - I cut a channel in the styrofoam roof insulation to run them across to where the existing wire run in the canvas is. I would recommend fusing at least one of the wires (both if your total Voc is over 50V) somewhere up in the roof in case you develop a short in or around the canvas wire run.

The question now is would I run new wires from the charge controller to the battery on the tongue? Or can I tap into the existing wiring (pic 6) that already runs from this cabinet to the battery box on the tongue? Or is there some other way the charge controller should be wired into this set up? Lastly, since the new LifePo battery is sealed should I consider moving it inside and off the tongue as I have read other people have done?

For now you can just do what Jwwif did and tap into the battery wires somewhere between the battery and the WFCO. I moved my battery off the tongue for two reasons - #1 to reduce my tongue weight and #2 to provide a more stable thermal environment for the battery. I believe you have a storage box? If so that might be a good compromise? It also means shorter wire runs if you are looking at adding inverters, etc, later.

Some other things to consider if they are not already on your radar:
- You will need to disable the existing charger in your converter and install a charger (or Inverter/charger if you want) with a LFP profile.
- If you want to charge your LFP battery off your tow vehicle don't forget to leave room for a DC-DC charger.

 

[Jwwiff]

Since I am using a FLA battery, the solar will charge it if I am not hooked to Shore Power and the Shore Power will charge it if solar is not putting out the necessary volts. Since both the MPPT controller and WFCO “see” the same battery, they will not fight if I am hooked to shore and the sun is out. Neither knows if there is one or more batteries there and just respond to the voltage level and march on with their own battery charging profiles.

The DC side of the WFCO is just battery power distribution and charging - no DC to AC (Inverter) function. As I mentioned with your Li battery, you would disconnect the WFCO as it does not have a profile for charging anything but a FLA battery. In that case you might consider a bus bar with multiple fuses for the DC circuits in the camper to take the place of the WFCO (for DC only). I have not dug into it to see if you can just disable the charging function and still use the fuse/distribution part only.

I would agree with TSQ did in moving the battery off the tongue if weight were a concern. With the Li types, you can put them in the living area as there is no outgassing during charging and it would help with weight and balance. Additionally, it takes out the long run from the back to the front and voltage drop is a function of gauge and run length. If you intend on drawing some heavy amps, then 10 might be too small without suffering line voltage drop.

It all starts with your load profile - how many amps, how long, etc. etc etc. The DIY Solar Forum is a good place to learn about sizing and performance of your system..

Thanks for the details. Jwwif, I understand having the MPPT wires going to the battery but why to the WFCO? Doesn't the WFCO just draw from the battery anyway?

 

[SteveP]

When I installed my Li battery I simply added a switch between the battery and the converter. Something I'd thought about for a long time for other reasons but this made it seem necessary. The only thing disconnected by the switch is the charge line, the 100 watt solar system remains connected and has provided all the charge needed except for about once a year using a stand alone LI capable battery charger. When plugged into Shore Power the converter provides needed 12 volt DC and the battery is isolated.

Because it has such low resistance to charge a depleted Li battery can overstress your alternator when towing so the switch also disconnects the battery from the TV charge line.

When I installed the solar panel on the roof I followed the power wires through the AC unit into the pup interior. I installed a jumper in the AC unit with MC 4 connectors on each end. I did have to drill and grommet one bulkhead in the AC unit. The wires exit the AC plenum right beside the plug wires for the AC and are connected at all times, so the panel can charge the battery while towing.

 

[TSQ]

I have not dug into it to see if you can just disable the charging function and still use the fuse/distribution part only.

oceanstater: Your "converter" is really three separate "systems" conveniently packaged together - AC distribution (breakers on the left), a battery charger (hidden inside), and DC distribution (fuses on the right):

(this is a converter I had sitting on my bench, similar but not exactly the same as yours)

To disable and isolate the internal battery charger:
1) unplug Shore Power
2) turn off the AC breakers
3) double check Shore Power is unplugged
4) remove the cover(s)
5) triple check Shore Power is unplugged
6) locate the black and white wires on the AC side that feed the battery charger and disconnect them. The black you want is usually on the 2nd breaker from the left. Tape up the ends with electrical tape and secure them somewhere out of the way.
7) replace the cover(s)
8) plug in Shore Power

To add another charger (ie: https://www.amazon.com/dp/B08NY23BKF/): you can either wire it directly into the AC distribution panel/breakers using the same breaker you removed the internal charger wire from or wire in a receptacle to that breaker and plug it into that.

If you add an Inverter/charger it will probably be a little different, especially if you have a three way fridge, aircon, 120V water heater, etc.

 

[oceanstater]

Excellent info from you all. Thank you. I had initially understood that the LifePo4 batteries were "plug and play / drop in" replacements for FLA (i've seen this marketing claim a lot). Seems that is not the case as you have pointed out (the WFCO is not set up to charge LifePo when plugged into Shore Power, and the vehicle cannot properly charge a LifePo when driving). To retain both charging scenarios, which I definitely want to do, I would need to a) install a new charger somewhere behind the WFCO that can handle LifePo when plugged into Shore Power b) install a new DC to DC charger to charge the LifePo when driving. To avoid having to cobble together various components and disable parts of the WFCO does it make sense to just replace the WFCO with an all-in-one solution? Another thread mentions the Progressive Dynamics PD4135KVW as a drop in replacement for the WFCO that can handle LifePo4 batteries. Does this also solve the vehicle charging problem?

 

[oceanstater]

I've got a thread going over in the "Power - Site Power/Batteries/Generators/Solar" forum if you have not seen it already: https://www.popupportal.com/threads/new-electrical-system-build-thread-lithium-solar.134726/. My single 100W panel mounted flat on the roof gives me between 5Ah/day (totally shaded) to 50Ah/day (full sun @~45° North) in the summer.

Have you done a load analysis? Do you know approximately what your daily consumption is?

We don't have much load other than one crucial item and that's a plug-in cooler (Costway 44qt.)
Costway says Energy consumption is 0.16 kwh/24 hrs. Generally it draws about 40-50 watts.
For our family of 5 this is the one luxury we depended on for last summer's 8000+ mi. road trip.
Unfortunately it will draw down a group 31 FLA to an unhealthy level pretty quickly.

Beyond that I have replaced all bulbs with LEDs, we run the 3-way frig off propane, we use the water pump for dishes, camper has no AC, and we use USB outlets I installed to charge devices.

 

[SteveP]

Rather than trying to put it all together again I'll refer you to a couple of previous posts:
https://www.popupportal.com/threads/upgraded-battery-and-box.125765/
https://www.popupportal.com/threads/lithium-ion-batteries.127157/#post-1310809
With the caveat that while all LiFePO4 batteries are chemically the same the Battery Management System can be unique to each individual brand. It is important to research the BMS of your battery to understand it's capabilities because a BMS fault can shut your battery down even though it's fully charged.

To bring it up to date, I installed an Li upgrade to the solar controller little over a year ago. And at our last camp the converter started acting funky, 12 VDC output voltage was all over the place, sometimes not enough to burn a couple of LEDs and at others as high as 17 volts so I when we got back I ordered and began install of a PD4135KVW. Unfortunately after I did the demo of the old ELX converter I blew out my knee while mowing so that's currently stalled. I will install an extra breaker, just for the converter, so that I can disconnect the converter by flipping a breaker. I intend to run the PD converter on it's standard gel setting. It has a boost output of 14.2, a charge output of 13.6 which drops to 13.2 after 36 hours of inactivity which sounds perfect for my BB battery. I will continue to use the Victron IP76 occasionally to insure the the battery cells are properly balanced.

I've never used 12 volt on my 3 way fridge, even while towing, so being able to charge from the TV is no longer important to me. The Dometic CFX 40 rides in and powered by the truck while traveling so that it's accessible on the road. The solar system keeps the pup battery charged while on the road.

EDIT: While LiFePO4 batteries can be used as a drop in replacement, to get the best result for the extra cost you do need to take a little care. Maintenance and management is different from LA batteries.

 

[TSQ]

I had initially understood that the LifePo4 batteries were "plug and play / drop in" replacements for FLA (i've seen this marketing claim a lot).

I would agree that that statement is true from a load perspective, but not true from the charging side of things.

The LFP batteries that we are talking about ("drop in ~12V 100Ah FLA replacements") are made up of a number of individual cells, each with a nomimal voltage of 3.2. A BMS (Battery Management System) is used to, among other things, maintain all the cells at the same voltage. In a balanced LFP battery you will nominally have 3.2+3.2+3.2+3.2=12.8 volts. The LFP cells may be damaged if they drop below 2.5 (x4 = 10) volts or rise above 3.65 (x4 = 14.6) volts for any length of time. Because it is impossible to manufacture the cells identically they will tend to drift over time and without intervention you could end up with something like 2.4+3.7+3.2+3.5 = 12.8 volts. Although the battery is still nominally at 12.8 volts there are two sets of cells that are in the danger zone (plus your capacity will be reduced). In order to maintain the balance between all the LFP cells the BMS uses a technique called "top balancing". Top balancing works by holding the battery at its maximum safe voltage (3.55~3.6 x4 = 14.2~14.4 volts) for a set length of time (typically 20 mins per 100Ah) while the BMS brings all the cells up to the same voltage.

So really you need a charger with adjustable voltage setpoints, and a timer on the absorbtion stage to properly charge a LFP battery and maximize its lifespan (and capacity).

To retain both charging scenarios, which I definitely want to do, I would need to a) install a new charger somewhere behind the WFCO that can handle LifePo when plugged into Shore Power b) install a new DC to DC charger to charge the LifePo when driving.

Unfortunately, yes.

Although your WFCO converter could at least put some kind of a charge in the LFP, it would not be a full charge and it would not be doing the battery's health any favours long term.

Without a DC-DC charger you will likely blow the fuse in your tow vehicle (or melt the wiring harness) because a discharged LFP battery will charge extremely rapidly if not regulated in some way.

To avoid having to cobble together various components and disable parts of the WFCO does it make sense to just replace the WFCO with an all-in-one solution? Another thread mentions the Progressive Dynamics PD4135KVW as a drop in replacement for the WFCO that can handle LifePo4 batteries. Does this also solve the vehicle charging problem?

I'm not familiar with Progressive Dynamics but my understanding (from reading their datasheets) is that it is basically the same converter as what you have, just with a more modern battery charger board. It will not help with vehicle or solar charging.

In my humble opinion your money would be better spent on the Victron Energy charger (top tier manufacturer, much more customizable) then a whole new converter (looks like it would be roughly the same price). Plus it would be a lot less wiring.

We don't have much load other than one crucial item and that's a plug-in cooler (Costway 44qt.)
Costway says Energy consumption is 0.16 kwh/24 hrs. Generally it draws about 40-50 watts.
For our family of 5 this is the one luxury we depended on for last summer's 8000+ mi. road trip.
Unfortunately it will draw down a group 31 FLA to an unhealthy level pretty quickly.

Beyond that I have replaced all bulbs with LEDs, we run the 3-way frig off propane, we use the water pump for dishes, camper has no AC, and we use USB outlets I installed to charge devices.

I don't think their numbers add up - at 40~50 W it would only take 3~4 hours of runtime to hit 160 Wh, and I'm guessing it runs more than 3~4 hours/day?

A good group 31 will have 12V x 100Ah = 1200Wh (call it 600 usable at 50% DoD). So if it only used 160Wh/day the battery should last nearly four days (ignoring the other loads) - does that match your observations?

You could also just keep the trailer as-is and use a "solar generator" thingy to power the 12V cooler:
https://www.amazon.com/stores/page/99746758-F3A8-47D1-B058-64E6745CBDB1
https://www.amazon.com/stores/page/11C0A120-9D73-4FF2-AC54-DB467827FBCB
(I'm not recommending any particular brand, just examples)

To do a full blown LFP system I'd say you would probably end up converting your Shore Power cable to a twist-lock inlet and using that locker space to house a fuse block, AC charger, DC-DC charger, and MPPT solar charger.

 

[oceanstater]

TSQ, thanks for the detailed response. I think i'm starting to wrap my head around it all. Any reason i would need a fuse block if i'm keeping the WFCO which already has a fuse block for DC distribution?

To do a full blown LFP system I'd say you would probably end up converting your Shore Power cable to a twist-lock inlet and using that locker space to house a fuse block, AC charger, DC-DC charger, and MPPT solar charger.

.... and the LFP battery at that rate: get the weight off the tongue and keep the system fairly self contained.

 

[TSQ]

TSQ, thanks for the detailed response. I think i'm starting to wrap my head around it all. Any reason i would need a fuse block if i'm keeping the WFCO which already has a fuse block for DC distribution?

Just for your chargers which will need fusing on the output side. You could do it with individual fuse holders but a small fuse block is neater, and includes a negative busbar.

I'll sketch something at lunch if I have a few minutes.

.... and the LFP battery at that rate: get the weight off the tongue and keep the system fairly self contained.

That's basically what I did with my setup.

 

[TSQ]

Any reason i would need a fuse block if i'm keeping the WFCO which already has a fuse block for DC distribution?

See attached,

 

[oceanstater]

TSQ. Your wiring diagram was immensely helpful. Thank you. I'm finally at the stage of installing the system: panels are on the roof attached to unistrut, solar cables are passing through an entry gland on the side of the roof and down the channel in the canvas, and old battery is disconnected and off the tongue. Before I start installing all the components and wires in the old 30A cable storage box of the camper I wanted to post my schematic and see if there's anything I'm missing or could do better. One question I have is do I need a circuit breaker on the +12V line from the alternator before it reaches the Renogy DCC30A? Thanks again for all the guidance.

 

[TSQ]

Nice schematic,

The +12V charge wire from your vehicle battery should be protected by a fuse (or circuit breaker) on the vehicle side and not need anything on the trailer side.

Consider a fuse or circuit breaker on your solar input in case you want to turn it off - I just use an inline ATO/ATC fuseholder (https://www.canadiantire.ca/en/pdp/littelfuse-hd-mini-in-line-fuse-holder-0201614p.html) so I can pull the fuse when the trailer is being stored. I have it up in the roof where the solar panel wires enter the trailer (inside) in case the power wires leading down inside the canvas get pinched.

You will want a #10 (minimum) for the negative from the 7 way connector to the fuse block, not a #14, to match the positive.

Ensure the negative from the 7 way connector is grounded to the trailer frame at some point, either up near the 7 way connector (where it is likely already grounded) or at the fuse block.

Ensure the AC ground from the WFCO to the frame is still good. This is often a bare copper wire from the factory.

Your battery over current device is pictured as a circuit breaker but labeled as a fuse - if it is actually a circuit breaker you won't need the seperate battery disconnect as you can just open the circuit breaker to turn off the battery. If it is a fuse keep the disconnect.

Consider wiring the negative wire from your Victron charger to the new fuse block - the way it is shown will not work for the battery monitor. Plus it is good practice to have both the + and - from a device terminate at the same place (makes trouble shooting later easier)

Consider wiring the Renogy DCC30S (negative and battery positive) to the new fuse block instead of the shunt and battery fuse/circuit breaker. This will keep all your distribution wiring together.

The Renogy DCC engine on detection is not the best. With a 2015 Toyota you may need to hook up the IGN+ sensor on the Renogy DCC30S to have the charger work correctly. When I was using mine I had it hooked up to the trailer running lights so I could force it to charge by driving with the vehicle lights on. Just something to keep in mind a you plan/run your wiring.

 

[SteveP]

TSQ may have already addressed this but the 80 amp breaker on the TV charge line is useless as well as redundant. The line should already be fused at the TV source and an 80 amp breaker provides no protection to a 10 gauge wire.

 

[oceanstater]

Got it. Thanks SteveP and TSQ. There is a 10ga white (negative) wire coming off the 7-pin which grounds to the chassis under the camper but then oddly disappears under/behind the fold-up kitchen galley. Everything from there back to the WFCO is 14ga except for my +12v black
wire (10ga). Easiest solution might be to run a new 10ga wire from the connector of the old FLA battery (pictured below) and run that back along with the breakaway switch + to my new install.

 

[SteveP]

The black wire from the plug should be connected to the battery fuse in the WFCO, check to make sure that's hot. Splice that and the breakaway switch into the aux/charge line on the 7 pin. Extend the white wire to the frame lug where the white from the 7 pin is connected. The brakes are already grounded to the frame and power will back feed to the switch if the 7 pin is disconnected.