Planning for solar installation this spring

[EnzoColorado]

My TT comes with a single Interstate SRM-24 battery. We camped for one season so far and never really lived off the battery in any of the campground except for maybe an hour where I didn't plug in shore power, and the battery indicator went from 4 lights to 3 lights.

This season we plan to camp at least 2 separate weeks without shore power. I don't want a noisy generator so need solar.

After reading on varies sources for a few days, this is what I'm thinking.

1.) sell the Interstate battery, and get two of these AGM batteries for 200 AH capacity: https://www.amazon.com/dp/B00S1RT58C/?coliid=I1D1MA2RB6OCWZ&colid=2AX6R5XMB9ZVD&psc=0&ref_=lv_ov_lig_dp_it

2.) buy two 100 watts panels like this Renogy panel: https://www.amazon.com/Renogy-Watts-Volts-Monocrystalline-Solar/dp/B009Z6CW7O

3.) get a MPPT charge controller, maybe this SolarEpic MPPT 30A controller: https://www.amazon.com/dp/B00ZV3I6OI/?coliid=I2NCX7KMV58EE4&colid=2AX6R5XMB9ZVD&psc=1&ref_=lv_ov_lig_dp_it

My TT has a under the bed storage area in the front of the trailer. The battery is current mounted on the tongue and there is enough space for two batteries there. So if I install the controller in the storage space, I think I can drill a hole in the floor and run the wires from the panels and to the batteries through there and somehow seal the hole.

What's the preferred way to mount the panels on the roof? I read of using 3M VHB tapes to tape the bottom of brackets to the room, then bolt the side of the brackets to the panels. I have never used VHB tapes and don't know first hand how secure this is. Would hate for the panel to fly off on the highway. If I drill the roof and screw the bracket to the roof, what's the best way to seal those holes? Silicone seal?

Another question is running the wires from the panels to the controller. The panels will be mounted near the rear of the trailer. I'm thinking run the wires down the back of the trailer, then underneath the trailer to the front where the storage compartment is and drill a hole in the floor to run the wires in. Is there any issues with length of the wire vs. power loss from the panel?

Lots questions. Never done any work on the trailer and never played with solar before. Thanks in advance.

[pianotuna]

Hi,

If the batteries were fully charged and disconnected you never did need to remove them from the RV. So, yes, with (or without) solar there is no need to remove them. Out put from panels rises as temperatures drop. However, the sun is lower in the sky, and has to shine through more atmosphere, so output overall is lower.

EnzoColorado wrote:
Okay now I have a storage question. In the past couple winters I stored the batteries in my garage. Now that I have the solar panels, do I still need to take the battery out and store in the garage in the winter, or will the charger controller able to maintain the battery despite the low temperature? The low's sometimes get to the single digits here in the winter, but mostly winter is sunny, so should able to provide more than enough charge through the panels.

[EnzoColorado]

Okay now I have a storage question. In the past couple winters I stored the batteries in my garage. Now that I have the solar panels, do I still need to take the battery out and store in the garage in the winter, or will the charger controller able to maintain the battery despite the low temperature? The low's sometimes get to the single digits here in the winter, but mostly winter is sunny, so should able to provide more than enough charge through the panels.

[davemhughes]

Fantastic thread and I read the Jbrowland install link. I learned a lot form everyone as I hunt for the best system for me to install on our AF 1140. Definitely looking for the higher watt panels instead of the lower watt ones.

[EnzoColorado]

OP here.

First camping trip last weekend off grid.

Campsite is pretty shaded in the trees. Some sky visible directly overhead.

Friday afternoon was partly sunny. Saturday morning was sunny but started sleeting and snowing by 2:30pm and never saw the sun/blue sky again by the time I left Sunday evening. Lowest battery reading on the controller was 66%. The weather was unusual for camping for us. Usually we get a lot run and hardly any shades. This is on of those remote USFS campgrounds at 10,600 ft.

On the other hand, my new Mr. Heater ventless heater worked but only if I kept at least two windows open.

[Andonso]

Looks like you got the system you wanted.

My experience camping in an RV with solar is often it relies on the type of climate you're are camping in.

I've camped off-grid for several months in the Pacific NW Cascades with a 125 watt solar panel and three ~100 ah RV batteries didn't suffice.

The 23' motorhome RV furnace with a 7 amp fan drained the three RV batteries to the point the solar and batteries only lasted 2 - 3 days as there wasn't enough sunlight to recharge the three batteries.

Once the batteries fall below 50 percent (which is not recommended) they become more and more difficult to recharge, often taking more than 24 hours at full charge to bring them back. If no sunlight there's no way to bring them back. If you have sunlight there needs to be enough to provide a sufficient charge rate to bring the batteries back.

I think minimally a RV needs 250 watts and true deep cycle batteries to extend for a week or more.

What you really want when planning on a solar system is one that can last longer than a the length of time you plan for a boondocking trip.

If you plan for a one week trip, plan minimally for two weeks or longer to potentially indefinitely. Solar relies on the weather so if you are planning a two week trip and have two weeks of rain, the solar plan for two weeks goes out the window.

If your camping in the desert with lots of sunlight is alot different from boondocking in the mountains with lots of trees and camping where it rains most of the time. One day of sunlight rarely is enough to charge batteries back to where they should be as most of the time you won't be charging near a maximum charge rate, perhaps 50 percent and possibly lower, sometimes charge rate goes up higher than it goes down again. Unless you are in a climate with 100 percent sunlight every day solar potentially varies quite a bit.

The less sunlight there is, more solar panels and batteries are required.

When boondocking I don't use the RV furnace and have installed a secondary catalytic heater.

Either a permanent RV catalytic heater or a Mr's Heater works.

RV furnaces aren't really designed for boondocking as they require a fan to run. Mine uses a 7 amp which causes a significant drain on the batteries.

I suppose if you have enough sunlight, solar panels and batteries the RV furnace fan may not make a big difference.

I also swapped out all my 12 volt light bulbs for LEDs. Then there are the water pump(s) which don't use alot of elect. but can make a difference when the batteries are low.

Once a RV looses 12 volts it dies and becomes a shelter.

[Boon_Docker]

Nice !

[EnzoColorado]

Boon Docker wrote:
Congrats on the new solar, you are going to love how quiet the new charging system is.
Did you go for the 200 watts?

Yes I did get 200 watts and two 100 amp AGM batteries.

[mikakuja]

Congrats on the new system!!!! You will love it. It's great charging batteries in silence!!

[Boon_Docker]

Congrats on the new solar, you are going to love how quiet the new charging system is.
Did you go for the 200 watts?

[EnzoColorado]

OP here.

Installation was successful this past weekend. It took two full days, mainly due to the weather. Saturday morning the camper was covered in two inches of snow, then sun came out and melted everything before rain came around 5 pm. Sunday was more of the same but rain in the morning instead of snow.

I got system live at around 5pm yesterday and the controller reported between 5 to 6 amps of charging from the panels.

Next step: replace the lights with LED lights.

[Harvey51]

Your tentative plan looks good to me. My plan was also for two Renogy 100 w panels, starting with one to gain some experience. Surprise, we are still using just one. We never hookup, leave the generator at home ... and the pair of Costco batteries have never been below 80%. No TV, use of propane for fridge and kettle, LED lights. The two iPads and phones are also moderate power users.

The Renogy panel came with an aluminum frame and brackets to screw onto the roof. I used a location where there was heavy plywood under the metal skin. I ran the power cable down the fridge vent about 10 feet to the PWM controller. I get a wee bit over 5 amps into the batteries on a sunny day with the batteries at 90%. Perhaps 25 amp-hours on a good day. The panel is mounted flat on the roof and we mostly camp at latitude 58 degrees. Clearly our old fridge uses less electricity than modern ones with defrosting.

I used the #10 wires that came with the Renogy kit. Others speak of much heavier wire but they have much higher current flowing. You could easily check it out before installing. Buy ten feet of #10 house wiring cable at the hardware store, hook it all up on the ground - panel to controller to batteries. Measure the voltage at the panel and at the controller. If you lose 20% of the voltage you need heavier wire. If you need 30 feet the voltage drop will be triple what you measure for 10 feet. Using two panels in series with the MPPT controller you will double the voltage and halve the per cent loss.

Good luck and happy camping! I recommend a battery monitor so you always know how the batteries are charged. I’m very happy with my $25 one from China via eBay.
eBay link

[Rbertalotto]

I just returned from two months and 9000 mile cross country trip. Only in RV park 10 nights with elec hookup. Used furnace nearly every night for first month (February) and then bought catalytic heater. Never used the generator entire trip. Ran TV,Amazon fire stick, hotspot, kurig coffee maker and toaster daily, charged laptop and cell phone daily. Boondocked most nights in rest areas. Week in Quartzite BLM. Few days in Joshua Tree BLM and few days in Anza Borrego BLM. Few days boondocked on PCH. Every day upon wakeup my batteries were at 70-80% and by 2pm, regardless of weather I was back to 100%.System worked great. Even on overcast days. Couldn't be more happy.
(3) 140w panels flat mounted
Bogart solar controller
Bogart Trimetric monitor
(2) 110 group 31 AGM batteries
4g wire
1000 watt inverter
All LED lights

[Almot]

Don, you are probably right.

My 490W flat array makes ~2A in November rain and overcast, but part of the reason is that batteries start in upper 80% on most days. Loads are light, almost zero draw overnight - replaced furnace with cat heater. Perennial dust on the panels needs to be taken care of... maybe... can't justify the effort :)...

[pianotuna]

Hi Almot,

From 256 watts of panels wired in series parallel (33 volts into a Blue Sky 3024di), I do get 3 to 4 amps in rain, and 1 to 2 amps in snow. In leafy shade harvest is 7 amps.

Today (2018 03 20) at 11:40 a.m. with overcast, the numbers are 15.1 volts @ 3.9 amps (58 watts). I just turned on the inverter and put on a load. Numbers went to 13.8 volts and 6.9 amps (95 watts).

I agree with the pricing for solar only.