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.

[Almot]

200+160=360W, yes, possible. In summer, with none or very little shade and when the weather is cooperating.

So, let me quote BFL13 here 😉 - "Solar is all or nothing". I would say, - "almost" nothing.

In winter - and many people do camp in winter in South and Southwest - 360W will be next to nothing under cloudy skies. With any rain, even light rain, it will be nothing, 0.5-1.0A at best. Triple the wattage, and increase battery bank to 3*100 AH 12V AH - fits on the trailer tongue nicely - and with those loads you'll still be in upper 90% by the evening.
Similar situation in diffused shade.

$1,000 would get them at least 600W solar on the roof, with controller and all.

If generator use is planned, it's a different kind of solar, they can get by with 200W or even 100W then.

[Jbrowland]

500 to 700 Watts is overkill for the OP’s needs in my opinion. Here are a few scenarios.

When I had my class C, I had a 160w on the roof and a 100w portable I could deploy as needed. I had 1 group 24 agm. That was enough for a week of dry camping for three people. The catch is we acted like we were tent camping. No TV, careful with lights, board games, and roasting marshmallows. Disconnecting was our family goal. If it was sunny, the 160w on the roof did the trick daily. This is close to what the OP has described.

Now we have a larger trailer that came with more creature comforts. We still try to disconnect but our travel style has changed a little. We sit in one place longer and we glamp more than tent camp with our RV. I find that 2 6v batteries, one 200w portable, and a small 2000w inverter genset that we try not to use too often does the trick. I will likely add another 160w panel on the roof. This is for us, the perfect combo of affordability and reliability in most weather conditions where we live and RV.

I think my second scenario will work for the OP’s needs and all for about $1000. That gets the OP a small, off brand generator like the Westinghouse for rainy days, a 160w panel on the roof, a small portable panel, and two Interstate 6v batteries.

[Boon_Docker]

Almot wrote:
To minimize power loss, go with MPPT in series. Then you can use a regular #10 MC4 cable on arrays up to 500 or 700W.

X2 on the MPPT controller.

[Almot]

To minimize power loss, go with MPPT in series. Then you can use a regular #10 MC4 cable on arrays up to 500 or 700W.

[allen8106]

EnzoColorado wrote:
1.) sell the Interstate battery, and get two of these AGM batteries for 200 AH capacity.
Best bang for your buck and best performance is lead acid, I recommend Crown.

2.) buy two 100 watts panels like this Renogy panel:
Renogy panels aren't to terribly bad.

3.) get a MPPT charge controller, maybe this SolarEpic MPPT 30A
For 200 watts you don't need MPPT, is overkill for what you are doing and costs more for little to no benefit.

What's the preferred way to mount the panels on the roof?
Buy or make some L brackets and screw them to the roof deck. cover the screw heads and brackets with self leveling Dicor.

Is there any issues with length of the wire vs. power loss from the panel?
Make sure to use a good online power loss calculator to determine wires sizes based on your run lengths. I used #8 from the panels to a combiner box then #6 to the controller.

[Almot]

You will be drawing 20-30 AH a day, including everything but furnace.

Half of this - 8 or 14 AH - will be propane fridge. Hard to tell, some fridges are real hogs.

[EnzoColorado]

OP here.

Our energy requirement is fairly small compare to most people's. No TV, no inverter. We do bring a chromebook with us on our trips but that thing last 12 to 14 hours on a single charge, and so far we have not ever charged it on a week long camping trip. We tend to stay away from electronics when camping.

The one number I can't figure out is how much power the fridge draws when it's on propane.

[Almot]

OP is long gone, but he said he is not planning to get inverter. Hence, - low energy use. Having 4*6V would help in really bad weather scenario, like 3 or 4 days of rain, but not essential otherwise.

I hope Keymastr spoke metaphorically when saying "lights".
Lights are the smallest item on energy balance sheet if convert them to LED of same brightness. 2 double dome lights, i.e. 4 bulbs total, 3 hours a day, will draw 30 AH in a WEEK. Propane fridge draw and laptop are usually the biggest loads in this scenario (and furnace, if you need it).

[Boon_Docker]

"After you have a large battery bank solar makes sense but with only 200 AH you will need a lot of solar to keep the lights on a full week" ???????

I have 225 AH (2- 6v GC2) and 200 watts solar and do just fine boon docking for weeks at a time.

[keymastr]

For the two trips you plan on taking solar is a complete waste of money until you have a much larger battery bank. If it were me I would get 4 GC2 6volt FLA batteries from Costco for $85 each mounted on the tongue in the traditional manner. That will be enough juice for what you want to do if you are the least bit careful and can be installed in minutes.

After you have a large battery bank solar makes sense but with only 200 AH you will need a lot of solar to keep the lights on a full week. One cloudy day or a campsite in the trees and it's over.

[mikakuja]

I am currently running a 200w system with a 30A PWM controller and 2 225AH GC2 lead acid batteries. With a family of four charging computers, phones and regular use of the LED lihgts etc, we can keep the batteries in the 80-90% range if we are lucky enough to get a moderate amount of sun on the panels. Most of the time we only get a couple hours of sun due to trees and and have to run the inverter gen for a couple hours every few days to keep the batteries topped up. We tried using our coffee pot on the inverter, and while it works fine it just plain consumes too much power for a 200w system to recover from, even with a decent amount of sun... I have switched back to a stove top percolator coffee pot, which does a great job.
We will be adding another 200 watts this year to further reduce generator useage...

[Almot]

Hate to argue with West, as he is usually right - this time too.

But Eterna tape won't do same good job under the bracket footprint on arched trailer roof. Dicor and Geocel fill the voids better. OTH, might not be necessary to seal under the footprint when holes are sealed. Just feels better when the whole area is sealed, better support too.

[westend]

Tip for sealing fasteners: If you spin a screw through Eternabond tape, the sealant in the tape will wind up the threads and seal the fastener as it's driven in. If you're fast on the speed of installing the fastener (cordless drill fast), the Eternabond adhesive will even cover the head of the screw.

[Almot]

Sorry, gave wrong name for Geocel (on roof screws). It's Geocel Advanced RV EPDM.

Or Dicor Lap Sealant.

I used both. Geocel is less bubbling and shrinking than Dicor. It dries faster, on a hot day can be "too fast".

[Almot]

200 Ah is plenty for TV, lights and pump if solar will bring them to upper 90% by sunset. With 500W array it will, unless it rains all day. Grey skies without rain is fine. If it rains nonstop for 2 or 3 days, you need either much more battery, or a generator. Or shut the TV off and go to sleep.

Lights should be replaced with LED, they come in all types of sockets. Saves a lot of energy.

You will be able to have limited use of microwave, but with only 200 AH bank I would rather not.

OEM battery gauge with 3 or 4 indicators - Full/Half/Empty - is a joke. Most solar controllers come with voltmeter or some sort of display, it gives a better info on battery charge than OEM gauge.