Installing a Solar System in a 2018 Cougar Travel Trailer

[WJQ]

I am nearly finished with this project but wanted to share some of what I learned. First, there are two parts to a solar system install: 1) the solar battery charging circuit, and 2) the 120 Volt inverter power circuit. You can do the charging circuit and boondock wherever you want and keep your 12 Volt system operating for as long as the sun shines!

To run any 120 Volt powered circuits, number 2) is required and is more complex and more expensive. This travel trailer had no solar "prewire," and I am glad. From what I learned in another thread, the prewire system in a Keystone 2020 TT would not support my power use objectives. I will explain later.

Every solar battery charging system will have three major components: 1) solar panels, 2) a charge controller, and 3) batteries for storing solar power. These are the same batteries that are charged from shore power. Any DIY travel trailer owner can Google "RV solar systems" and get overwhelmed with information

The key steps are as follows:

1. System design with your long term objectives in mind. This means identifying your power needs. For a charging system, you need less power than you would need for a charging and inverter system for producing 120 Volt power. I suggest you install a system with at least 200 Watts of solar panel capacity. More is better if you are going to eventually install an inverter.

2.) Mounting the panels. You can read about this on various websites. Mounting also deciding on the power needs and thus solar panel(s) size.

3.) For an RV without prewiring, one of the biggest challenges is getting the solar wire routed through your roof to the charge controller, which should be near your batteries. Then, sealing your roof once your wiring is installed.

4.) Wiring your charge controller and connecting to the batteries.

My solar battery charging system uses a single 280 Watt residential solar panel (about 40 in by 60 in) with a 37-Volt DC output. Most RV panels are about 1/2 this size, with 17 Volt output. Either can be made to work, and the panel selection also depends on the roof space available to install the panels. High panel voltage means smaller solar wire sizes, less voltage drop, and easier wire routing.

My charge controller is a Victron Smart Solar 100/20 MPPT model. I manage and monitor the state of operation and battery charge, using its Bluetooth connectivity to my cell phone. This system charges my two 6-volt US Battery 232 Amp-hour batteries connected in series. These batteries are similar to the more well known Trojan T105's.

This part of the system has been operational for about four months. When I am camping, it provides more than enough power for all of my 12 Volt needs as long as I want. I even installed a small 300-watt pure sine inverter as a temporary solution for enough 120 V power to run a TV. When the trailer is in storage, it keeps my batteries on the float voltage without boiling out the water.

If a system like this meets your needs, you are done. If you want 120 Volt power, stay tuned. I will add more information in the next day or so.

[roadglide]

How did you run the wires from your 300 amp inverter to your camper?

[JRTJH]

Originally Posted by roadglide

How did you run the wires from your 300 amp inverter to your camper?

I think he is using a 300 WATT inverter, not a 300 AMP one.

[WJQ]

The 300 Watt inverter is just temporary so I just ran an extension cord from the inverter through a window near the TV and and another cord inside to run the TV and Satelite box.

This works but that is not what I want as the final instalation. I am going to extend my post today but running wires is still an issue.

[WJQ]

This post describes the inverter part of the system and at the end I am looking for some ideas for running the AC wire from the inverter to the future subpanel.

First, the requirements part. I want to run a TV and Satellite Box (total power 120 Watts) but for extended periods -- especially if/when football returns. I also want to be able to run our microwave for short periods 3 to 5 minutes couple of times a day. The microwave needs 1100 Watts. I also decided I want all of my 120V outlets powered (they are on a single GFCI Protected circuit anyway) -- although only a few will ever be in use at one time. With all outlets powered, we can charge phone or tooth brushes in all locations.

I created a spreadsheet that estimated the number of AC and DC amp-hours I needed for the various uses we expect in summer and in the colder spring and fall (main difference is the 12 Volt DC heater fan). The end result was that I predicted enough amp-hours from the solar system to meet my needs.
I found the following link tody on another post: RV Solar Power Calculator -- http://www.rvsolarsystemsonline.com/wattage-calculator/ This is similar to my spreadsheet.

For my system, I am installing a 2000 W Aims Power Pure Sine Inverter PWRIX2000UL with an internal transfer switch and pass-through capability when not powered.

I will be removing two circuits from the existing power center -- the GFCI Outlet circuit and the microwave circuit. This design requires a new subpanel where the two removed circuits will be powered by the inverter system. The subpanel will have two 15 AMP circuit breakers. In my trailer, the refrigerator AC outlet is connected to the Conv/Gen circuit in the power center. I plan to move the refrigerator AC circuit from its current location and to the microwave circuit. with this change I can pre-cool the refrig on solar power before departure. I measured the refrig power needed, and it is about 300 Watts AC. In a 24 hour period, this power demad needs 60 amp-hours. If I have done my math corectly, my solar power capability is about 58 amp-hours for 5 hours of sunshine and 50% efficiency (clouds, dirt on the panel, etc). So I am within the inverter power capability and the solar power generation capability. Again, this is just the refrigerator precooling power use. When camping it will be operating on propane.

If I knew how to attach a diagram to a post, I have a pretty clear one-line diagram that would be useful to others wanting to install a system similar to mine.

I recently spoke with Tech Support at MFCO (power center for my TT) about this design. The tech told me WFCO had developed a dual bus power center that eliminates the need for a separate subpanel. I did not ask the price. But my Square D subpanell is going to cost about $35 for the panel and two breakers so I chose that path. I think it will be easer to install.

Now I will describe the physical location of the components and where I need to route the wiring. Here is where I could use the advice from some of our senior members.

In my trailer as for most travel trailers, the batteries are located up front. The power center is located in a cabinet on the rear wall. The shore power cord is located about 4 to 5 feet from the rear wall of the trailer. There is a 4 inch electrical box under the sink in this location. This is where I will install the subpanel.

The inverter will be installed in the storage area in the front of the trailer. Here my DC wires will be connected to the batteries. I will include a switch to isolate the inverter from the batteries when service is required. The DC wiring will be about 4 feet in length. With both the TV and Microwave operating (1220 wats), the power from the batteries will be 102amps. The voltage drop in 4 AWG copper wire will be about 0.2 volts. Here is where it would be nice to have a real electrician check my calculations.

I will discuss the AC wiring from the inverter to the subpanel and to the shore power connection in a subsequent post.

[WJQ]

Here is where some experienced help would be appreciated. From the location where I can bring the AC lines through the floor (one AC line for shore power and one for inverter power to the sub panel), the distance to the subpanel location is about 18 feet. I am considering two options:

1. Run the two wires through 3/4 to 1 inc pvc electrical conduit attached to the bottom of the trailer below the coroplast. Conduit clamps can be attached to the cross braces to hold the conduit.

2. Remove the coroplast in areas large enough to pll the wires through . The question here is what will I find behind the coroplast? There are three or four cross braces welded to the fraim sides that the coroplast is presently screwed to. Are there holes in the crosses braces that I can fun the wires through? Will I be able to route the wires around the various grey and black water tanks? WHat else is there to interfere with the wire routing?

The second option is the cleanest if it will work. All wires will be out of sight. No conduit to be visible.

Anyway, if someone who has worked on the underside of this or a similar trailer can advise me on issues with wire routing number 2, it would be very helpful

[roadglide]

I’m using 3000 Amis inverter 2 poll relay I ran 14 Romax by removing bolts on one side of the corlplast the camper wires came into the breaker box near the frigid. That was easy connection to the box pull the box out there was a lot of room . I would forget about using microwave with the 2 k inverter isn’t practical in a rv.

[WJQ]

Thanks for your comments on the coroplast.

What wire size did you use to connect the batteries to the Inverter?

How many batteries and what amp-hours do you have for the 3000 watt inverter?

[roadglide]

Originally Posted by WJQ

Thanks for your comments on the coroplast.

What wire size did you use to connect the batteries to the Inverter?

How many batteries and what amp-hours do you have for the 3000 watt inverter?

I used 2/0 welding lead wire . I have 3 AGM 115 AH 12 V Duracell . I should have used 2 K inverter .

[WJQ]

Thanks, Roadglide!

Since you system is different than mine, I am hoping to get confirmation that your solution will work on my Cougar.

For other members who may have looked at my thread, my last step is running the AC wiring.

I understand the electrical side (although I have upped the DC wire size since my last post) but I am uncertail as how to route the AC wiring (14-2 Romex) from the inverter located in the front of the trailer near the batteries to a subpanel that will be located near the rear.

I woul like to route it above the coroplast (inside the frame) but since I have never removed the coroplast, I don't know what I will find.

One member indicated that what I want to do is possible -- at lease for his 311 Impact. There is cross bracing (Steel braces welded to each side of the frame) at four locations as I go from front to the rear that I must work around and water storage tanks as well.

I am hopeful that the braces have "holes" in them where I can route the wiring. My coroplast is fasened with "nails" so I would like to know what I might find before I start to remove it.

Thanks for you help.

[chuckster57]

PM received

If you remove the nails you can run the solar wires inside the frame, there will be plenty of spaces to run them through any cross members and around tanks. Use a stainless steel self taping screw in place of the nails. You can also run all the inverter wiring while it’s open.

[flybouy]

I also got your PM. Agree with Chuck, would only add use SS fender washers under the screws.

[WJQ]

Roadglide

Your comments were helpful but there is one I do not understand. You say to not try to use a microwave with a 2000 Watt inverter You may know something that I have missed. So, tell me why? Here is my system description.

My microwave input power is 1350 Watts. My only other power demand when I will use the microwave would be for the TV & satellite box with a total of 120 Watts. DC loads could be the water pump, lights, etc. Any other power use at the same time is miniscule (cell phone chargers, tablet, toothbrush, etc).

I have prepared a spreadsheet where I have estimated my total DC and AC power use. For the microwave, I estimated 10 minutes a day for a total of 1.88 amp-hours. My total estimated amp-hours use in the summer (no furnace use) is 25.6 amp-hours. It goes to about 67 amp-hours in the colder time of year.

My two batters will provide 116 amp-hours (two US Battery 2200 with full charge 232 amp-hours) at the 50% max draw down level. Lastly, my solar power produced at 50% derate to my panel to acount for dirt, sun angle, season, etc., is 57 amp-hours.

Thus, it appears I have plenty of battery power to use the microwave for 10 minutes (or more if needed) a day and can replenish it with solar on a daily basis.

What have I missed? Thanks again.

[WJQ]

Thanks to all. You have made my day. Now, I can proceed with confidence!

I will add to this thread when it all comes together and hopefully works!

If it does work as planned, my little Honda generator will be depressed when I bring her home with a full tank of gas!

[flybouy]

Originally Posted by WJQ

Thanks to all. You have made my day. Now, I can proceed with confidence!

I will add to this thread when it all comes together and hopefully works!

If it does work as planned, my little Honda generator will be depressed when I bring her home with a full tank of gas!

That little Honda will turn into a caped super hero if you get a rainy weekend !

[WJQ]

I totally agree. That is why the Honda will always come along. But, out here in the west, we are so dry that when it rains, it is a relief. Yesterday we had a "downpour" that delivered 0.07 inch. That was the first rain in 6 to 8 weeks.

[flybouy]

Originally Posted by WJQ

I totally agree. That is why the Honda will always come along. But, out here in the west, we are so dry that when it rains, it is a relief. Yesterday we had a "downpour" that delivered 0.07 inch. That was the first rain in 6 to 8 weeks.

Wish I could send of the surplus out there from here. We are over 7" of rainfall for the entire month and that was a week ago.

[WJQ]

In completing my inverter wiring, I removed the Keystone Battery Disconnect switch so I could look at the wall thickness on the front of the storage compartment. I wanted to mount somethin else on that panel. The thickness is about 1.8 of an inch.

However, I also found that the nuts on the disconnect switch are loose. It looks like the nuts were finger tight. The split ring lock washers are not compressed. This manufacturing error could easily cut off power at a very inopportune time and the fault would be hard to find.

While I can easily tighten the nuts, the question comes to mind, why do I need that switch? As many members already know, that switch does not cut off all power from the batteries. There are items that recieve power all of the time even when the trailer is in storage.

So, if it does not cut off all power, is there any reason I can't remove it?

[Javi]

Originally Posted by WJQ

In completing my inverter wiring, I removed the Keystone Battery Disconnect switch so I could look at the wall thickness on the front of the storage compartment. I wanted to mount somethin else on that panel. The thickness is about 1.8 of an inch.

However, I also found that the nuts on the disconnect switch are loose. It looks like the nuts were finger tight. The split ring lock washers are not compressed. This manufacturing error could easily cut off power at a very inopportune time and the fault would be hard to find.

While I can easily tighten the nuts, the question comes to mind, why do I need that switch? As many members already know, that switch does not cut off all power from the batteries. There are items that recieve power all of the time even when the trailer is in storage.

So, if it does not cut off all power, is there any reason I can't remove it?

A better choice might be to wire it so that it does indeed disconnect the battery from all parasitic drain..

[WJQ]

Thanks for your response.

I have already installed a total disconnect switch, However, given the poor documentation associated with this Keystone Trailer, it is possible there might be some subtle problem I have overlooked. Thus, my effort to reach out to other members.