1990 Ford E350 Minnie Winnie 27FT - Place 400lb of solar on the roof?

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Riley90

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I just purchased a used 1990 Ford E350 Minnie Winnie 27FT. After my measurements, I found it is at least 90 inches wide, and I am assuming it is 27FT long on the ceiling.

Since I plan to use it boondocking a lot, I plan to run AC without a generator, an 8000 BTU window AC should be about 900watts an hour. and I will remove all the vents and AC on the roof to make it flat.

I checked "445W 72Split-Cell Silver Mono Solar Panel by Solarever," which is 82.44*42.86, and 27ft = 324 inches.

((324)/(42.86))=7.5 Panels, I plan to place seven panels, which is 51.8 lb * 7 =362 lb. and gives me 3115 watts of solar.

I plan to replace the roof anyway because it's already soft, but would this still be too much for a 30-year-old RV?

According to the original manual, they do not recommend anything over 100lb. I am thinking about the worst case is I have to use CIGS Solar panels to make it lighter, but that is the last option because of the cost. Also, I think the glass solar panels work as another layer of insulation to block heat from sunshine from passing down to the ceiling.
 

Mark_K5LXP

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Given your RV is BER already I don't see that you have a lot to lose by trying. If it's rated to be walked on then that panel weight distributed over the entire top would not seem too much. If you are the belt and suspender type you could augment what's there with some additional framing secured at the edges. You didn't mention storage or whether you've done any testing to see what effect 8K BTU would have in that volume. The panel shading will help a bit but it's still a large poorly insulated box. My vote would be to test a window AC unit in there on shore power first to determine viability.

Mark B.
Albuquerque, NM
 

Riley90

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I got an RV Mobile service estimate to replace the roof - $4500 for everything.
But he has no experience with such an extensive system and not confident on holding 400 lb of solar even with a new roof...
 

Alontheway

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The weight will be no issues whatsoever. You are spreading this weight out over a huge area. Consider an AC unit on the roof is over 100lbs and sits on a 16x16 inch hole with no issues.
your 50 lb panel covering 42 by 82 inches is pretty spread out over the roof.
How are the walls?
Have you looked at 5,000BTU window AC units? They use less power, but also give less cooling.
The best option for AC on solar is to use a mini-split unit. These are just made to run more efficiently and will give you more BTUs per battery amp. You can also run a small generator at night and because the AC is efficient you will get more hours out of the very small gas tank on the small generator. A few hours will make a difference. I have a roof 9000BTU unit and run a 2000 watt inv gen and use a full tank (I think about a gallon or 0.9) for 10-11 hours of AC time if I keep the temps just cool enough. I have a small well insulated camper though, your bigger one might cause AC compressor. to run most of the time.

I would strongly suggest to not remove the roof vents. These are valuable and many times will be plenty to keep you cool without using AC.
I would deploy portable solar panels if you need to make up for the lost room the vents take up. With portable ones you can aim them directly at the sun which gives you more amps anyway.

There are rigs out there with the entire roof full, and ones that also have hinged panels that can be tilted to the sun. This is huge. They have hinge on one side and always park facing the same compass direction (facing west and the panels tilt to the left of the rig which is South). With tilting panels you can get away with fewer panels. That said, you will never get the full rating out of the panels if they will be flat on the roof, and the sun is to the side, never overhead unless you are below Tropics.
Keep this in mind when doing the math.
 

Riley90

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The weight will be no issues whatsoever. You are spreading this weight out over a huge area. Consider an AC unit on the roof is over 100lbs and sits on a 16x16 inch hole with no issues.
your 50 lb panel covering 42 by 82 inches is pretty spread out over the roof.
How are the walls?
Have you looked at 5,000BTU window AC units? They use less power, but also give less cooling.
The best option for AC on solar is to use a mini-split unit. These are just made to run more efficiently and will give you more BTUs per battery amp. You can also run a small generator at night and because the AC is efficient you will get more hours out of the very small gas tank on the small generator. A few hours will make a difference. I have a roof 9000BTU unit and run a 2000 watt inv gen and use a full tank (I think about a gallon or 0.9) for 10-11 hours of AC time if I keep the temps just cool enough. I have a small well insulated camper though, your bigger one might cause AC compressor. to run most of the time.

I would strongly suggest to not remove the roof vents. These are valuable and many times will be plenty to keep you cool without using AC.
I would deploy portable solar panels if you need to make up for the lost room the vents take up. With portable ones you can aim them directly at the sun which gives you more amps anyway.

There are rigs out there with the entire roof full, and ones that also have hinged panels that can be tilted to the sun. This is huge. They have hinge on one side and always park facing the same compass direction (facing west and the panels tilt to the left of the rig which is South). With tilting panels you can get away with fewer panels. That said, you will never get the full rating out of the panels if they will be flat on the roof, and the sun is to the side, never overhead unless you are below Tropics.
Keep this in mind when doing the math.
The walls are hard as I push them. Only one corner is soft.

The roof seems to require to be replaced as it is very soft when someone walks on it. I got quoted $4600 to get it done.

I think I will keep one vent at the top of the kitchen. When I cook food, I might need it, but that means the solar panel might have to be raised and placed on top of vents.

I don't have a lot of confidence in a 30-year-old car. If the roof is so heavy and the underside is light, maybe the RV will get blown over by the wind on the highway?

Maybe the frame/walls are not designed to hold so much and are already worn out. Could it collapse?

I also realized that I couldn't have seven panels because I must make a serial connection of 2 or 4, I must put 6 or 8 panels, I am hoping to put eight panels(3560 watts total), but I think it will be a little over the roof, 42.86*8 = 342.88 inch = 28.5 FT, I might have to enforce a rack extended from the roof, which is extra load on the roof, sounds like a bad idea, but having 6 panels means I would lose 900 watts of solar.

For now, the RV is still at the repair shop, trying to find out what is wrong with the smog check.

is there any specific mini-split I should look into?
 

Alontheway

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Well, good news is that the soft roof is the paneling between and the ribs are probably steel and very intact, though maybe with some rust. It is the steel frame, not the paneling, that will be holding the weight.
As far as walking on it, yes, you walk on the panels unless you can see where the ribs are and aim for them.
Go to youtube and watch other solar campers with ACs. One guy has a drawer where he deploys another big row of panels.
If you raise a panel over a vent then you get into wind issues.
It is OK, and will technically improve mpg's, to let the panels hang over the rear by a foot or so. I did that on a Truck Camper, as I had no more roof room, and I made it to be an awning for the rear door too. Win win.
 

Mark_K5LXP

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Until you have some idea of heat loading in this unit there's no way to guess how many Btu you're going to need to maintain any given interior temperature. One could just pick the "biggest" that can be practically run based on solar input and live with what you get. One data point I can offer is in my 30' RV with a single 13500 rooftop AC I get about a 20 degree delta daytime outdoor to indoor.

Mark B.
Albuquerque, NM
 

Riley90

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The repair shop estimated me $3800 to replace tires, replace suspension shocks, transmission hoses, set engine timing for smog, change oil, and drop the fuel tank to inspect the issue with the gas gauge.
they said my transmission and engine are in great shape tho.

It seems the whole project will cost about $25k, the RV was $7500, repair $4000, replace roof $4500, solar and battery $6000 and AC/Fridge/Water heater will cost another $2000

7500+4000+4500+6000+2000 = $24000
 

Henry J Fate

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The repair shop estimated me $3800 to replace tires, replace suspension shocks, transmission hoses, set engine timing for smog, change oil, and drop the fuel tank to inspect the issue with the gas gauge.
they said my transmission and engine are in great shape tho.

It seems the whole project will cost about $25k, the RV was $7500, repair $4000, replace roof $4500, solar and battery $6000 and AC/Fridge/Water heater will cost another $2000

7500+4000+4500+6000+2000 = $24000

Just make sure the chassis has plenty of life left. Spending 24k on a 32 year old motorhome has its risk factors. I wouldn't say that's a whole lot of money but it certainly would feel that way if the chassis produced a major failure.

You should also have a generator with you. You will need it. Solar is not a dependable power source by itself especially when air conditioning is a factor. You could consider wind as another source. Wind generators can work day or night. Geographics play a big role in the practical use of wind generation but it is something to consider. Some of the wind generators on boats are getting pretty slick.
 

Alontheway

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So, now you figured out everyone using small generators while boondocking are doing it for a good reason. Way way cheaper to use a generator for AC than a roof full of panels and a trunk full of batteries that still wont get you through the night.
It can be done, and has been, but consider the reality, and consider how long that old beater RV will last, you will never get your money back out of it
 

garyb1st

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You might want to actually measure the length of the roof. In looking at a 1990 Winnebago brochure, the length is about 27 feet but, that's the overall length. The usable area on top is probably closer to 20 - 22 feet. Measure before buying more panels than you can use.
 
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