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.

[Bill_Satellite]

EnzoColorado wrote:
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.

What do you plan to do for power once the sun goes down. Those 2 batteries won't provide much in the way of reserve capacity if you want to watch TV or turn on a couple of lights. Cooking with electric is out of the question so you just need to ensure you keep your expectations realistic and have a backup plan for solar which likely will include a small Honda type generator at a minimum.

[Almot]

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


Chinese cr-ap. Formerly Panasonic. I have them, performed poorly from the day one. If it wasn't for my big solar and very low energy use, I would have to buy new batteries after a year. Bite the bullet and get AGM Dekka or Fullriver. Or go cheap, install 2*6V wet cells on the hitch - if they fit. Or buy one more Interstate like the one you have.

I have never used VHB tapes and don't know first hand how secure this is.

Not secure, on plywood-rubber roof. Panels will fly away with pieces of membrane still holding nicely to brackets.

If I drill the roof and screw the bracket to the roof, what's the best way to seal those holes? Silicone seal?


Not silicone. Use Dicor lap sealant or Geocel Proflex RV. Put plenty of sealant under the bracket, wet the screw in sealant before driving it in, and (maybe) cover the screw heads with sealant. Use stainless hardware on roof screws and on bolts/nuts on panels.

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?

With series 500W array and MPPT the power loss is negligible, up to ~100-150ft distance, with wire #10. Haven't heard of anybody running it down the back of the trailer though.

[Almot]

EnzoColorado wrote:
Another question, can any of these controllers be mounted on the outside?

You're thinking too much 🙂

Good advice from members already - get much more solar than planned 200W. I have 490W, made of 2*245W panels, it's cheaper/simpler than 5*100W. I don't carry a generator.

On typical TT with particle board roof and rubber-ish membrane, most common way to mount panels is Z-brackets. It's best to make it yourself of pieces of 2x2 or 3x3 aluminum angle, bolted together to make a Z. 1/4 bolts and nuts into panel bottom, #10 sheet metal screws with sealant into roof - done. My brackets were different though.

Get at least 200 AH battery bank. Trailer tongue should be able to accommodate 3*100 AH 12V batteries or 2*125 AH 6V batts (these are taller, may or may not fit with the front wall "hump"). Another option is to put AGM battereries in front storage.

My 3*100 AGM are in front storage for security and other reasons. Controller is 2ft away, mounted on bedroom wall above that front storage. #10 cable from panels is routed through the fridge vent into microwave cabinet and behind the cabinets along the ceiling/wall, to bedroom controller. Where it's not hidden in cabinets, I used plastic molding - Wiremold cover.

Controller location - I "thought" of mounting it in front storage, but inside it is better protected from marine air and dust, decent MPPT controllers of that size are not cheap.

There is zillion options for mounting all this.

[ksg5000]

Have you considered buying a generator?

[EnzoColorado]

SoundGuy wrote:

does your fridge have a climate control heater (probably does) and if so do you know how to turn it off? If it can't be turned off then you want to add your own switch so you can as that heating element will unnecessarily draw down your battery reserve when dry camping. Conservation is the key. 😉

I don't know the answer to that one, will have to go home and dig up the owner's manual to check, thank you for that suggestion.

If I don't plan to get an inverter, is there any advantage to installing the AGM batteries inside the storage area? We do tend to store a lot things down there and will hate to lose usable storage space. I understand the advantage of mounting the controller as close to the battery as possible. That's why I asked if the controller can be mounted externally. From what I read, I think the Grape Solar 40 AMP PWM can be mounted outside?

[SoundGuy]

EnzoColorado wrote:
We have two trips this year without shore power. Both trips will be one week long.

We don't have a TV in the trailer. I've been thinking about usage for awhile ...

If your interior light fixtures don't currently have LED bulbs in them then change 'em to minimize battery draw down due to lighting. Next step is to use portable lights for some of your needs. Third step is to absolutely minimize your use of lights when dry camping - e.g. no need to leave any lights on inside the camper if everyone is outside sitting around the campfire. Teach the kids to turn 'em off whenever possible.

If you're even contemplating inverter use I'd suggest you locate it in the front pass through storage compartment to keep it out of the elements but also mount AGM batteries in there as well and connect to them with short, heavy gauge cables that will minimize voltage drop. That's what I'm doing this spring by replacing my tongue mounted flooded battery with AGM in the pass through and eliminating 6' (12' total) of 4 gauge cable, using at most 18" long 1 gauge or 2 gauge. An inverter can be really handy but IMO hardly worth it if use is restricted to powering just one device. If 200 watts of solar is going to be your only method of recharging I'd forget the inverter, forget any 120 vac devices, and minimize your use of everything powered by 12 vdc, reserving it for those devices you absolutely must power, such as your fridge. Which brings up the question - does your fridge have a climate control heater (probably does) and if so do you know how to turn it off? If it can't be turned off then you want to add your own switch so you can as that heating element will unnecessarily draw down your battery reserve when dry camping. Conservation is the key. 😉

[EnzoColorado]

Another question, can any of these controllers be mounted on the outside?

[EnzoColorado]

Okay, let's me clarify my planned trips this year. We have two trips this year without shore power. Both trips will be one week long.

We don't have a TV in the trailer. I've been thinking about usage for awhile, and came up with these:

6 lights: two of them are in the bunk beds for the kids so maybe on for an hour or two at most per day. Two are in the main living area so perhaps 3 hours per day. The kitchen light is used about an hour per day, and light in over the master bed is on for an hour at most.

Charging two cell phones. Right now we plug them into the wall receptacles. I'm going to install a 12 V DC USB charging port https://www.amazon.com/dp/B00ZOIIQAO/?coliid=I1RDZ232RP6CCD&colid=2AX6R5XMB9ZVD&psc=0&ref_=lv_ov_lig_dp_it to charge the phones once a day. Each phone's battery is rated 2700 mA.

Coffee maker: We use a Mr. Coffee 12 cup maker, once in the morning. It's rated at 900 watts and it's on for about 10 minutes per day. I did some rough calculation and this will use ~14 amps hours. We also have a French Press so if we don't want to install an inverter, then we go with the French Press which won't use any power.

The only other things that uses power at least in the summer is the Waterpik flosser. This will require an inverter. If this end up being the only thing that uses inverter, I may invest in a rechargeable battery powered version of the Waterpik.

Both trips are summer trips. I know in the cooler weather we will need to run the heater which uses quite a bit of power. How much, I don't know yet.

I read the freecampsite articles. So question now is PWM charge controller is fine now, no need for MPPT controllers? That will save quite a bit.

[goducks10]

How does battery quality affect solar needs. If you have say 4 12V G24 batteries vs 4 AGM 6V batteries aren't the AGMs going to drain slower therefore requiring less solar for recharging? Or are amp hours amp hours?
Don't rag on me I'm pretty much solar dumb.
My thinking is the better the batteries the less solar watts needed?

[Rbertalotto]

I’ve been on the road on a cross country trip sines Feb 5.....it is now March 14. Have not used generator once and had electric hook up only a couple nights. Was not happy with solar until I had over 400w of solar. Now VERY pleased. And I don’t use 12v sparingly. Tv for hours a night, Kureg coffee, toaster, heater fan......
You can find my installation and real world experience on my web site www.rvbprecision.com

[pianotuna]

Hi MrWizard,

When I was part time and had 875 amp-hours of battery bank the 256 watts of solar would fully charge the bank between trips. I could do about 7 days and would usually run out of water before I ran out of power.

At the time panels were $5.50 per watt. Now they are incredibly inexpensive.

200 amp-hours is a tiny bank for boondocking for 2 weeks. I'd suggest he go "overboard" on the solar and have enough to run everything he wants during daylight hours.

[MrWizard]

normally i would agree, we had over 600watts on the Safari

BUT
PT, haven't you done very well 256w and you are an electric user
perhaps, you can give him some pointers

[pianotuna]

Unless you wish to be a power miser 200 watts of solar is not going to be enough.

Read this series:

https://freecampsites.net/adding-solar/