Solar panel system advice/personal experiences please

Almot wrote:
My memory didn't fail me, you roof is not like on typical travel trailer. Looks like aluminum or fiberglass sheet, probably there is no 1/2" particle board underneath, and no massive rafters.

Tilt while in storage... I don't know. I did just the opposite - disconnected one of my two 250W flat panels, so there wouldn't be any high current running in my absence. Next time I think I won't disconnect it, because batteries in storage are floating and will draw very low current, be it with 1 or 2 panels.

Yup, aluminum roof. The "U" channels are lagged into the ceiling rafters.
Yes, I keep the current from the solar going all the time. It is the best part of solar and RV's, your batteries are always charged. Last week, I first added water to the 6V's. That is about 1 1/2 yrs. of charging. I should have added a little sooner, probably at a 6 mo. interval but electrolyte was still above the plate surface.

Almot wrote:
Consumeratlarge - No, rivet nuts are not "blind" rivets.

I think I may have made myself misunderstood. About rivnuts, or rivet nuts. I refer to them as 'blind' fasteners, because they are installed from one side of a structure, and can be used to fasten from one side of the structure, (not needing nuts or washers on the inside of the structure). I use them on non structural airplane parts, like fairings, and have the tools. I was comparing them to blind rivets, because the threaded puller is similar to the way a blind riveter works, mushrooming the blind side by pulling. BTW, I always chase each one with a tap chucked into a little battery drill. That way, you will never have one spin, since the threads also can get a little distorted after being pulled.

Thanks for the details on your aluminum mounts, sounds like a good setup, like you said. Especially for lots of outdoor exposure, which is where the panels do their best! When I laid mine out on the roof, I knew it was going to be a lot of wood screws into thin plywood, so I like your comment about spreading the load of all of those wood screws.

My memory didn't fail me, you roof is not like on typical travel trailer. Looks like aluminum or fiberglass sheet, probably there is no 1/2" particle board underneath, and no massive rafters.

Tilt while in storage... I don't know. I did just the opposite - disconnected one of my two 250W flat panels, so there wouldn't be any high current running in my absence. Next time I think I won't disconnect it, because batteries in storage are floating and will draw very low current, be it with 1 or 2 panels.

Westend is using VERY long aluminum angles, and they indeed distribute all the weight and stress over wider area. I think his roof is different, so a different design was needed. Besides, he is tilting his panels - not sure how often - so there is more stress.

I occasionally have some stress but it isn't from my solar installation :W
My 235W module is tilted all the time while in storage.

Consumeratlarge - No, rivet nuts are not "blind" rivets. When installed, they leave you with threaded through-hole, so the length of the bolt is not crucial. Check mcmastercarr.com to see how it looks. It was the only place where I could find stainless rivet nuts with 1/4" thread. Not cheap. You will also need Wrench-Drive Rivet Nut Installation Tool tool, costs about $30 at the same McMaster.

Or just put a pin through, forget the rivet nut. I installed rivet nuts (and secure pin-in-hex bolts) because of theft problem is Mexico, but panels prices have dropped since then, I doubt stealing it from the roof is worth the efforts.

My aluminum angles are not very long, 6". They don't distribute the panel weight, but rather the stress of anchor screws in 5/8" particle board.

I tried to hit the rafters whenever possible, but locating rafters is a pain, and it's not possible to have all the screws in rafters. So the angle has to be at least 2" wide, preferably 3 or 4", to drive 4 or 5 short screws where there is no rafter. 4" wide angle @6" length allows to drive 5 or 6 screws in corners and center, if you have to. For a flat install that will never be tilted, I think 4 screws per bracket is adequate. I got all my aluminum from http://www.onlinemetals.com - all kinds of angles, all sizes, like 3x3, 3x4, 4x4 - whatever you need. They will cut it for you into 6" pieces for a nominal price, though a hack saw isn't difficult to use either.

Westend is using VERY long aluminum angles, and they indeed distribute all the weight and stress over wider area. I think his roof is different, so a different design was needed. Besides, he is tilting his panels - not sure how often ;) - so there is more stress.

I painted my aluminum brackets with Rustoleum paint, and don't see corrosion problems so far. Electrochemical corrosion of dissimilar metals (like stainless screw in aluminum bracket) requires wet contact. With screw heads buried in sealant, there is no wet contact. It will take a long time for my 1/4" thick aluminum brackets to corrode, I suspect they will outlast me and my trailer.

OP - one of the first answers, somewhere on the very 1st page, has the link titled "Various Installs". And other info that will be useful and necessary to you. In the "Installs" you will find that people have as little as 200W and as much as 900W, with different panels and controllers. It depends on your situation.

Happy holidays.

Almot wrote:

westend wrote:
Sorry to have come down a bit harsh on the plastic mounts, they may be just the ticket for some folks. I get somewhat wound up with my DIY metal working sometimes and can't see the reason to do it any other way.
I see where most guys figure out quickly that, if attaching a module using the factory made holes, it is darn near impossible to remove the module from the mounts because of the fastener locations.

I think I came down on plastic mounts harsher yet, and for a good reason. Plastic will work for "some" folks - for those who are not camped out in hot and sunny areas most of the year.

I agree, and my place in the high mesa of NM is mounted with metal tabs, but it's not bumping down the road. I like your idea of spreading out the load with the angled aluminum. How about rivnuts into the frame of the panel? They are threaded, but install similarly to pop rivets, and leave you with a blind threaded hole?

BTW, the plastic on those mounts is pretty stout, and I do keep it under cover most of the time at this point. Again, my main reason for selecting it was having the widest, least damaging surface to that roof. I have a virtual sundamage laboratory in Florida and NM. I have seen that plastic is not a permanent material, it changes as it ages, especially in the sun. But, thicker has always fared better.

One of my storage buildings gets hot in the summer, and some of the foam products disintegrate without a bit of sun exposure, just from the heat! Aluminum is one of my favorite materials for sun and corrosion resistance, but seems to accelerate corrosion of connected dissimilar metals, so good idea using the stainless hardware, it definitely does better longer with aluminum.

Quote: Great info!! What exact type setup of solar panels do you have and charge controller? Oh and what is your location?
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For the hard core setup on the remote camper:
3 approx. 190watt grid-tie panels. They were cheaper back in the day, and have a higher voltage, (approx. 37v) which is good for keeping wiring gauge smaller.

These tie into a metal switch box, wired in parallel. Inline Fuses on each panel wire inside the box. A cutoff switch on the box (inexpensive disconnect at Home Depot). Then, a short 8 gauge wire to the controller. Outback 60 amp MPPT controller. Highly customizable, and will turn a higher voltage panel to whatever voltage you want your batteries to have. It has done many years in a hot and cold environment in the high mesas of NM, 7500'.

8 or 10 gauge wire from there to batteries, but one of those resettable, blade switch circuit breakers inline. Sized to the wire. 30amps, I'm thinking.

Batteries are standard 6v golf cart batteries, series/parallel to give 12v. output. I put them in a plastic trunk, with a covered vent to the roof, screened to keep things out. Homemade 2 gauge(? recalling from a while ago) connectors with crimped brass eyes between batteries. Final wire to inverter, as short as possible, with a 200amp resettable circuit breaker just outside the battery box inline with the wire to the inverter. After inverter, couple of 15amp circuit breakers in a cheap residential box, then into an RV plug, like you would see at a 30A camp site. Then plug in the trailer plug.

The generator ties in to the inverter, if you want to use it for load sharing or charging, but we haven't really needed it. If you'd like to do that, look for an inverter with a load transfer switch built in, or wire that in yourself, so that the generator doesn't get fed current when it's off.

Xantrex prosine inverter 1800w. Two can be put together and synch to give 240v if you need that. The inverter remote control just needs a phone wire with standard plugs to connect it to wherever you want the remote panel display and buttons to control it. That way you can see amperage draw, amps going in, voltage, etc, as well as turn the inverter off when you're not using it.

Panels are cheaper, way cheaper, than when I bought. The controllers are still pricey, and the tracking mounts for fixed installations are pricey. So, go with as many panels as possible, bigger wire than you first think of, and you will be able to fine tune yourself to not even need power plugs.....except in hot, humid conditions!

My RV setup is more modest. 2 150w panels, a MPPT controller, fuses, inline circuit breakers, going to those strange 'marine' 12v batteries. I will upgrade those first when they get more tired. That rig lives in Florida, but I store it under a roof.

I keep a cheap on/off type of controller for backup in case the fancier ones stop working. A cheap, less efficient inverter, for backup would be good too, if your power needs are critical.

Renton, permanent or semi-permanent setup like snowbirds is different from traveling. There are (usually) more needs, but there are (usually) less restrictions as to the battery size, panel tilt, wiring etc. You should tailor your solar to your particular situation and to your particular lifestyle. In sunny destinations in winter (say, October through April), a generator-free living is possible with flat solar anywhere from 300W. Some people can't make it with 900W, in the same location.
Do you know already what kind of RV-ing you are going to do?

Controller size and type depends on solar wattage and type. Up to 280W it's usually PWM controller and 12V panels in parallel, or one 24V 250W panel and MPPT controller. From 300W and on, it's 24V panels in either series or parallel, and MPPT controller of appropriate size.
Have you determined already how much solar wattage you need?

Battery bank and inverter size depend on number and wattage of 110V gadgets that you use.
Have you decided already what gadgets you are going to need?

Great info!! What exact type setup of solar panels do you have and charge controller? Oh and what is your location?

consumeratlarge wrote:
We have a solar setup on our remote camper, which is more or less permanently in place with a septic tank. It's way off the grid with no electric utilities. Using the 1800w inverter, my wife uses her hair dryer, electric toaster, and I run the 1.5 hp water pump, saws, air compressors, etc. And it's all up to float charge by late morning. THen, on a hot day, it will run a swamp cooler to cool off the inside during the afternoon. And the batteries are just like what you have in many RVs 4x6v golf cart. We have a small 1800w generator, but never need to run it.

RVs are amazing that they can be self sufficient for several days, but in my case, the stock electrical 12v system would run out too quickly, especially using the furnace. Best part about a solar system is the battery charging can be tailored perfectly to whatever batteries you have, then it's set it and forget it. You will always have something working to put them back to a good charge.

I have 6 battery chargers, plus dozens of battery tenders for all the equipment and vehicles, but none of them will have the flexibility of a solar charging setup, in terms of customizing the charge rate, float charge, under and over voltage setpoints, equalization settings.....

westend wrote:
Sorry to have come down a bit harsh on the plastic mounts, they may be just the ticket for some folks. I get somewhat wound up with my DIY metal working sometimes and can't see the reason to do it any other way.
I see where most guys figure out quickly that, if attaching a module using the factory made holes, it is darn near impossible to remove the module from the mounts because of the fastener locations.

I think I came down on plastic mounts harsher yet, and for a good reason. Plastic will work for "some" folks - for those who are not camped out in hot and sunny areas most of the year. UV radiation turns plastic into dust. Plastic plumbing vent on my trailer, left on the camp in North Baja, has crumbled to pieces in one year. This location is not that much hotter and sunnier than AZ. Fiberglass cover on AC developed small spiderweb cracks around corner bolts, and I can't think of any other reason than sun. Oddly, soft plastic vent on the fridge is like new. Some plastics are more UV-resistant than others, though I still don't see why not using aluminum mounts.

No matter what material you use, the mounts should allow taking the panel off without removing tapping screws from the roof. As noted, factory holes in the bottom of the panel frame are difficult to access once the panel is installed.

Some people use L-brackets with bolt or pin into the panel side, the L is basically a short 5"-6" piece of 3x3 or 4x4 aluminum angle. Others use Z-brackets made of pieces of aluminum angle, one piece is attached to the roof, another one to the bottom of the panel, and then both pieces are bolted together. This allows for height adjustment, so you don't need to be very precise.

Important detail - the panel should conform to the roof slope, rather than being horizontal relatively to the ground. That little slope will help shedding water and debris.