Advice for roof mounting a solar panel awning.

[wopachop]

I want to add around 1000w-2000w of solar to a toyhauler. Its a Forest River and the build quality was very very very bad. Im talking roof joists were not even screwed together.
Be awesome to build a sliding mount for the solar panels so that some of them could act like mini awnings. Have you guys seen some big failures where high winds rip off panels that people have tilted on their roofs? This trailer is so poorly insulated im hoping solar panels will shade and cool the trailer. Or will they heat up and warm the trailer? Or does it come down to how much space is between the panel and the roof?
Its the type of situation where overkill means more holes in the roof membrane. So im hoping to learn what is strong and normal and what is just way overkill.

 

[justinm001]

I think it would be sweet to see someone stack 2 sets of panels then have it so the bottom row would just slide out on rails and be used as an awning. Volta did something similar below.

I'd be worried about your roof handling the weight though. Having heavy panels past your roof would really need some counterweight as hanging weight is much heavier... then there's wind to worry about. There are smaller trailers that put solar on the side of their trailer then manually lift it to act as a roof too.

Yes solar panels create heat between the panel and the roof. That's why the stickon panels rarely last more than a year or so. Having some space helps the heat get absorbed from ambient temps but it's definitely not going to help cool your rv

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[Aussieguy]

lots of people have used heavy duty drawer slides + air cylinders
search youtube for videos of them opening

 

[HarryN]

You are right that Forest River and similar setups built by the companies owned by W Buffet - mostly are not built very well.

Your instinct that you will need to essentially reinforce the roof structure to add solar is correct.

Common methods are 8020 profiles such as 1530S or similar like people use on vans for solar framing.

An air gap is important. If the panels are right next to the roof it will just be hotter inside. If there is a gap - then it provides shade and a way for the hot air to escape.

 

[Bigbillsd]

Here is a video of a guy I know that has an awning mounted on his trailer he pulls behind his RV. I would imagine he probably has a different video that goes into that special mount for them to slide out. -Bill

He has specs of his slidout solar panel platform

 

[NotToFast]

Here is a video of a guy I know that has an awning mounted on his trailer he pulls behind his RV. I would imagine he probably has a different video that goes into that special mount for them to slide out. -Bill

He has specs of his slidout solar panel platform

Let him come on up to the Northeast where the sun might not shine for a week, and most camping spots are under trees. Solar mega projects are for the desert. And who really want to live in the desert?

 

[rustythorn]

while i still might have stacked panels on the roof, i'm also planning on a deployable solar array/awning. i've spent a lot of time thinking about it and looked at various approaches by other people. i'm currently working something like below. i have the panels and hopefully i'll pick up the angle aluminum tomorrow. for more crazy ideas and possibly useless tips follow my blog in my signature link

ps, why would anyone want to live outside of a desert?

 

[Bigbillsd]

while i still might have stacked panels on the roof, i'm also planning on a deployable solar array/awning. i've spent a lot of time thinking about it and looked at various approaches by other people. i'm currently working something like below. i have the panels and hopefully i'll pick up the angle aluminum tomorrow. for more crazy ideas and possibly useless tips follow my blog in my signature link

ps, why would anyone want to live outside of a desert?

View attachment 166930

ps, why would anyone want to live outside of a desert?

They probably like it warm all year. There is a huge influx of folks heading south each winter to the southwest deserts. And unlike the south east there aren't any bugs unless you camp near a watered agricultral area.

 

[wopachop]

Thanks for the replies.
I'm realizing how RV mounted is the worse ever. If you consider price.

 

[chrisski]

IMO, covering your roof with solar panels would make no difference Temperature wise. I saw an experiment for some trailers at work where a tarp was added and made no difference to the inside temps.

I have a 35’ RV with 1650 watts of panels on the roof, and 900 watts in 100 watt portable panels on the ground.

I thought about awnings and slide outs. Too expensive to be done correctly.

Not that hard to make solar awnings out of 100 watt portable panels and PVC pipe and hang it on the slide out, but that won’t hold up to the wind. I saw a decent slide out for $100 each that could accommodate a 100 watt panel. I found no decent, cheap slide outs from furniture for outdoor use.

I’m a big believer in portable panels after the roof fills up.

 

[wopachop]

Thats a lot of power!! Mostly heating and cooling the trailer and water heater?
Im a big believer in insulation. Fighting a battle that shouldnt be there. If i could go back i would research what brands and model put a high focus on insulating the trailer. I thought about drilling holes in my ceiling and renting an insulation sprayer from lowes. Or use foam boards glued to the ceiling and forget how it looks. Maybe seal the underside with that thin board trailers use. Or install enough solar that i can run a heater or AC. I keep thinking shade would be a huge difference in summer. Just like with a car. The interior temps in direct sunlight are insane. My trailer is definitely hotter than ambient temps by a lot during summer days. Even with something like 300cfm of fresh air blowing in. I use a 12v bilge blower but its not enough to cool the trailer down to ambient temps. Tricky part is trying to do this in super dusty conditions. Opening a window and turning on a roof vent would bring dust unfortunately.
It all makes lots of solar seem appealing. Little easier to run a 500w heater than a 1500w air conditioner. At least it aint hot all year long.

Heres a joke that aint funny. What do you think would happen if a worker grabbed a tube of self leveling sealant for installing the windows?
hint: remember when homer ate that hot pepper??

 

[chrisski]

Mostly heating and cooling the trailer and water heater?

The 2.5 kW of panels is to run one of two Air Conditioners in my RV. If I turn the hot waters on, the air conditioner must go off. Both those items add up to more than my 3 kW inverter can handle.

 

[justinm001]

IMO, covering your roof with solar panels would make no difference Temperature wise. I saw an experiment for some trailers at work where a tarp was added and made no difference to the inside temps.

Covering a trailer with a tarp definitely would cool the inside temps in the sun provided there's air between the tarp and the roof. There's an R value that air gap provides. Air is a very good insulator.

Tarp just on the roof doesn't do much of anything as it cant absorb heat and just transfers almost all of it below.

 

[wopachop]

I thought about trying a 24v water heater element and using battery power. Then it only draws something like 700w.
I put mine on one of those wifi meters. Kind of fun to track it. Mine pulls around 1300w and took just over an hour with the water already starting around 70F. Wasnt cold outside. It used more power than i expected the meter said 1.5kwh total.
At some point i wanted to test how much power is consumed if i leave it on for a few days straight. Since the water is already hot it would do several smaller cycles. Curious how much more power it would use leaving it on. Thought about adding foam to the face of the water heater for additional insulation.
I often use propane to heat it. Once i get more solar and bigger batteries i wanted to try the 24v element trick and do that when the sun is out. Only have a 1000w inverter but i just wouldnt run other stuff while the water is heating. Kind of nice because i can control the water heater from my cell phone when im using electric. I can get stuck out of town and then its silly having the water heater cycling. Or turn it on before i get home so its ready.
I tried to use them for my AC. But it pulls just over the 1500w limit for the wifi meters i bought. They only allow for 1 hour of operation in a 24 hour period if it senses over 1500w. To me its fun seeing graphs and data of whats being pulled.
Was using a small mini fridge for a bit. That silly thing would turn on for 2 mins and 20 seconds, then turn off for 10 minutes. I think it must be on a timed cycle, instead of measuring the temperature inside the fridge. I thought it might be bad for my inverter to get cycled like that every 12 minutes? So i unplugged and eventually want to get a big 12v cooler. Or run the regular fridge on propane. Trying to switch to using more electric and solar. My current solar cant keep up with the 250w my fridge pulls on electric mode. Stays on practically the entire time too in the summer. So freakin inefficient.

 

[justinm001]

I thought about trying a 24v water heater element and using battery power. Then it only draws something like 700w.
I put mine on one of those wifi meters. Kind of fun to track it. Mine pulls around 1300w and took just over an hour with the water already starting around 70F. Wasnt cold outside. It used more power than i expected the meter said 1.5kwh total.
At some point i wanted to test how much power is consumed if i leave it on for a few days straight. Since the water is already hot it would do several smaller cycles. Curious how much more power it would use leaving it on. Thought about adding foam to the face of the water heater for additional insulation.
I often use propane to heat it. Once i get more solar and bigger batteries i wanted to try the 24v element trick and do that when the sun is out. Only have a 1000w inverter but i just wouldnt run other stuff while the water is heating. Kind of nice because i can control the water heater from my cell phone when im using electric. I can get stuck out of town and then its silly having the water heater cycling. Or turn it on before i get home so its ready.
I tried to use them for my AC. But it pulls just over the 1500w limit for the wifi meters i bought. They only allow for 1 hour of operation in a 24 hour period if it senses over 1500w. To me its fun seeing graphs and data of whats being pulled.
Was using a small mini fridge for a bit. That silly thing would turn on for 2 mins and 20 seconds, then turn off for 10 minutes. I think it must be on a timed cycle, instead of measuring the temperature inside the fridge. I thought it might be bad for my inverter to get cycled like that every 12 minutes? So i unplugged and eventually want to get a big 12v cooler. Or run the regular fridge on propane. Trying to switch to using more electric and solar. My current solar cant keep up with the 250w my fridge pulls on electric mode. Stays on practically the entire time too in the summer. So freakin inefficient.

Water heaters don't make a difference in the voltage or if AC or DC, it's just the wattage which determines how fast it heats up then the cycling depends on how well the tank is insulated.

I've seen people use systems to turn on a relay to their DC water heater when their batteries are almost full. This way excess solar isn't wasted but used to heat the water. Could even use this with propane.

Propane is much more efficient at heating than electric anything.

 

[wopachop]

Another thing was trying to use air and the attic space of the trailer as an air insulator. I put a temp meter up there a few years back and it was roasting. I think around 120-130F range. I thought about venting that space with fresh air, to make the interior trailer space cooler.
Turns out some nicer RVs have little attic vents. Sticking out of the roof. Similar to a house the hot air rises out naturally. I was thinking more about using my MaxxAir vent. Which i did last summer. I have 3 roof vents. MaxxAir is the middle vent. If you turn the fan on, but then use cardboard and tape or clear plastic to seal the vent, it pulls air from the attic and other 2 vents. It worked decent. Air would be sucked from the trailer, through the attic space, then out the top. Need to invest in more temp meters. The ones i had died. The nice one on amazon is like 80 bucks. Seems a bit high but it does read pressure. Thats off interest for me. I try to keep my trailer in a positive air pressure. Using HEPA filtered air. So that dust cant be sucked in all the little cracks. I even tape my window vents. In the winter with condensation it forms little lakes!!! You guys have any temp meters you like? I had the RV whisper setup for awhile. It was nice. Checking on the trailer with a cell phone. They switched to a new model and my older one wasnt compatible.

 

[justinm001]

Another thing was trying to use air and the attic space of the trailer as an air insulator. I put a temp meter up there a few years back and it was roasting. I think around 120-130F range. I thought about venting that space with fresh air, to make the interior trailer space cooler.
Turns out some nicer RVs have little attic vents. Sticking out of the roof. Similar to a house the hot air rises out naturally. I was thinking more about using my MaxxAir vent. Which i did last summer. I have 3 roof vents. MaxxAir is the middle vent. If you turn the fan on, but then use cardboard and tape or clear plastic to seal the vent, it pulls air from the attic and other 2 vents. It worked decent. Air would be sucked from the trailer, through the attic space, then out the top. Need to invest in more temp meters. The ones i had died. The nice one on amazon is like 80 bucks. Seems a bit high but it does read pressure. Thats off interest for me. I try to keep my trailer in a positive air pressure. Using HEPA filtered air. So that dust cant be sucked in all the little cracks. I even tape my window vents. In the winter with condensation it forms little lakes!!! You guys have any temp meters you like? I had the RV whisper setup for awhile. It was nice. Checking on the trailer with a cell phone. They switched to a new model and my older one wasnt compatible.

I use ruuvi sensors. They integrate with Victron which logs everything. You could get those with a CerboGX-S with a Bluetooth usb and get logging per minute for 6 months on their app

 

[wopachop]

There was a guy on an RV forum that put a 24v rated water heater element into his 12v water heater so it would draw half the watts and he could heat using solar and batteries. Just takes twice as long of course. For whatever reason his inverter was too small, or the 1400watt sagged his batteries too much.

 

[justinm001]

I've never seen an "attic" in an rv, usually it's foam (either closed cell or just Styrofoam) between plywood. Mines stainless steel roofing then closed cell foam then 1in plywood then leather covering. I do have an attic vent thingy on the roof but not really sure if it goes anywhere. I figured it was just installed for a bathroom vent or something.

Water heater holes usually are universal and the elements are cheap. They even make ones that'll fit in RV drain plugs. I'm planning on putting a 10/12gal apartment/commercial water heater with AC then adding a 48v dc element so I can use the extra solar to keep warm and/or ac when actually in use. Then wrap it in insulation and build a plywood box around it to keep the heat in. I figured if I take showers in the morning then it'll need to sit for 12+ hours. Also figured I could put a button to turn on the heater element when taking a shower so it stayed warm. Ideally set the AC element low and DC very high then use an electric temp controlled shower knob so I'll get the same temp water regardless if the tank temp is 110 or 140f and not deal with adjusting knobs.

 

[wopachop]

I don't think you can get a tank style water heater to stay warm even with both elements running. They have internal baffles to try and keep the incoming cold water from mixing with the remaining hot water. That must help. Once you have used what the tank holds the water will come out cold.
I will sometimes run the 1400watt element and the propane heater. It extends the hot water a little. But will never be able to heat the incoming 2 gallons per minute fast enough to act like a tankless heater.

 

[justinm001]

I don't think you can get a tank style water heater to stay warm even with both elements running. They have internal baffles to try and keep the incoming cold water from mixing with the remaining hot water. That must help. Once you have used what the tank holds the water will come out cold.
I will sometimes run the 1400watt element and the propane heater. It extends the hot water a little. But will never be able to heat the incoming 2 gallons per minute fast enough to act like a tankless heater.

Correct, typically incoming water has a pipe pushing it at the bottom of the tank and the hot water flows from the top so it'll drain the hot before the cold. But running the heater or both heaters will help just not much. Might add 1 more gallon of hot during the shower might add 4 just depends.

 

[wopachop]

Wait a second. I might be way off about the 24v water heater element. Maybe he used a 220v water heater element on his 120v water heater. Confusing myself here. Doesnt that 1/4 the power?
Say you take a 1000watt 220v element and give it 120v. Does it produce 500w or 250w? I feel so braindead right now!! Could go for a drink and maybe some food.