OverTheTopCargoTrailer 7 x 16

[bdosborn]

You might want to look at an Endless Breeze fan to supplement you PC fans. I use one to blow air from window to window over the bed and its the best. 900 CFM and it's on sale at PPL for $55.

Endless Breeze



Bruce

[bigbendhiker]

You might want to look at an Endless Breeze fan to supplement you PC fans. I use one to blow air from window to window over the bed and its the best. 900 CFM and it's on sale at PPL for $55.

Endless Breeze



Bruce

I like the looks of this fan. I may look at using one in my build. It looks like it would move more air than the O2Cool fan. Anybody have experience with both to compare?

[bdosborn]

I replaced an O2 fan with the Endless Breeze. The Endless Breeze kicked the 02s butt.

Bruce

[OverTheTopCargoTrailer]

If you don't post here everyday...I gotta keep saying its a real pain in the butt..
as its different again from a few months back....

First I need to rest up so I can add my comments a little latter, I would like to go into a little more details and tips of my improvements to Shadow Catcher first design, which I must say without him, It would not have been possible to push the envelope this far. This weekend it should hit 90 deg outside and then I can do a better test as to how well it will cool my 7 x 16' So far I can tell you that it works pretty well at 85 degrees. One thing I wanna say 100% for sure is that you get much better performance with the unit sitting on top of the trailer, also I have the 3" blower running at full speed, 130 cfm its a little loud but really kicks ass. I also have a couple of PMW controllers on order & would like to convert to a smooth 4" white sewer pipe & lower speed blower. One more thing I will need to do is install a sloped drain pan to allow the condensate water to drain off of the trailer roof.

After some more testing today starting at 12 noon I turned on the ac as it was about 90 deg outside & 82 deg inside the trailer & climbing fast. After running all day non stop the temp inside the trailer right now at 5 pm is about 78 deg and I was laying in there the whole time - watching tv, so you can add my body heat, the ARB coller and the tv heat to the equation to see that the unit is cooling pretty well. If the a/c was not on, the interior trailer temp would be approx. 98-100 degrees. The humidity for those of you who keep track of that sort of thing is about 30% so quite low. I would not assume it would work as well if humidity was at 65% or more, then additional BTU would be needed. Maybe someone can figure that out and post some figures for me ??

Here is where I started with the idea ... many, many thanks to shadow catcher

http://www.tnttt.com/viewtopic.php?f=30&t=44561&hilit=Hacking+a



I am basically pumping the air directly over my bed enclosure, which could also be blocked off to make a space as small as a tear drop
Not sure if its possible ?? yet, BUT my goal was to cool the trailer with only the solar panels



Im using some 360 deg fans to move the air around my bed.



This is the 4" deck plate that I installed on top of the roof.



Here a a blower that is available that is 4" at 240 cfm , I am currently using a 3" 140 cfm blower with 3" hoses.



My home made insulated box.



My home made insulated box.



Installing the deck plate.



Installing the deck plate.



Installing the deck plate.



The view from the top of the a/c on the trailer roof.



The view from the top of the a/c on the trailer roof.




A friend made this design so it will look worthy of OverTheTopCargoTrailer



Here is the PMW speed controller I ordered and am waiting for....
Finally figured out again how to make the pictures bigger also




As you can see that little 5,000 btu unit kicks ass at
58 degrees in the bed area......
P.S. the 28 deg is the temp inside my cooler not the outside temp

[LonerGlide]

How did u end up wiring ur panels? in paralell or in series?,,did u use combiner boxs?,,,, ive got about 700 watts a good charge controller and will have 600ah in batteries.,,thx so much!

[OverTheTopCargoTrailer]

Hi LonerGlide

if you read my thread all your questions are answered, with wiring diagrams and every detail from A-Z

Thanks for your interest


http://overthetopcargotrailer.blogspot.com/

[OverTheTopCargoTrailer]

I finally got around to updating my blog a little with lots of pictures and my AC hacking project,
It's sorta hard posting pictures here Grrrrrrrrrrr
Compared to the blog where I can select 10 & import all

If you don't wanna go with the standard roof top AC and see some crazy ideas
then it's a must read



http://overthetopcargotrailer.blogspot.com/

[OverTheTopCargoTrailer]

Hi Guys I'm hoping someone out there can help me with some answers


My current off grid system has 4 x 210W @ 26 watts Kyocera panels wired + to - . These four panels are connected to a 15 amp dc fuse. I am using a flex Max 80 charge controller on a max 60 amp fuse. The charge controller is connected to two Surrette 400 amp hour 12 volt batteries. The system works great.

I would like to purchase an additional 4 x 235 or 245 @ 30 watts Watt panels 65” x 39” solar panels to expand the system. The first problem is that the panels are already different wattage rating 210 and now ( 235 – 245 ) watt for example. The second issue is that the four 235 panels will be laying flat on a roof . The 4 x 210 panels will be installed 90 vertical on a house wall. Please imagine a south west facing house wall and a small flat roof area. So 4 panels @ 210 will be installed on the wall and 4 panels @ 235 will be installed flat on the roof. This is the only possible system configuration at this time. !!! I am located in the San Francisco Bay Area. The purpose of the system is to generate a min of 800 real time watts, let’s say between the hours of 1 PM and 5 PM during the summer months on sunny days. The power produced by the solar panel is required to power an 800 watt ac window air conditioning unit, during those hours – and to have a min or zero negative power drain from the battery system if at all possible ? If possible I would like to wire all 8 panels – through the same 15 amp dc breaker –into the flex max 80 charge controller which can handle 1250 watts max load ( but ) could also use 2 x 15 amp dc breakers if necessary.


In addition I would require a larger 2000 watt x 12 volt inverter ( Sine or Modified sine )? to power the 800 watt window ac load. If possible I would like to use the Modified sine inverter because the ac window unit is only intended - needed to have a 2-3 year service life and could be easily replaced. If your could answer as to help me out with your knowledge that would be great !!

I have been told there may be some issue as the 2 strings of panels are possible different volts 26 max for one 210 watt and 30 volts max for the 2nd 245 watt .... Now keep in mind the panels never generate the same volts unless its at the perfect angle to the sun anyway

The guy at the solar company said I may need 2 charge controllers ( one for each string of 4 panels ) due to different volts, but I have sean lots of you guys mix different size solar panels seemingly on the same charge controller ? When a panel is shades there are also less - different volts ? so what the hell

If someone has experience running his 5,000 to 10,000 Btu window ac with a cheap $200-$300 generator set as these are all Modified sine wave please let me know


I guess you guys are all figuring if that crazy OTTCT wants to light up New York ...
then let him figure it out by himself

Well after a little work I finally got it aced

But you all are going to have to stay tuned for the answer
BECAUSE - She is blowing in the wind

[8ball_99]

I think you would be So much better off just getting a small inverter generator to run the AC when needed.. Would be cheaper lighter and would give you much longer run times if needed..

[Mark519]

I don't think a modified sine wave inverter would run an air conditioner unit (induction motor) at all but it certainly doesn't seem like it would be good for it or efficient. The only option that came close when I researched it was these incredibly expensive 12V units http://www.dcairco.com/index.php/products/trucks/dc-9001-1224-vdc or http://www.dcairco.com/index.php/products/trucks/dc-8500 and even then running all day would require more battery power than solar could reasonably generate.

[bdosborn]

Can you post the electrical specs of the two different panels? Specifically the maximum power voltage (Vmpp) and maximum power current (Impp). We can use those values to get an idea of how well the panels will work together ins series or in parallel. I think you'd have plenty of panel to run the a/c. The a/c motor will run hotter and use more current on a MSW inverter but they usually will run. People on the RV.net forum have been doing it for limited runs.

Bruce

[OverTheTopCargoTrailer]

Damn I knew somebody was gonna ask me something hard like that

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The panels are within 10% on the volts and less then 5% on the amps

Those stupid solar people goofed around and now price is up 10 cents per watt

maybe I'll wait till its under $1.00 my magic number

8ball_99

I think you would be So much better off just getting a small inverter generator to run the AC when needed..
Would be cheaper lighter and would give you much longer run times if needed..


Psst .... dont tell anybody - that would be the easy way :-))


Mark519


I bet those dc ac units also cost a lot

[bdosborn]

I think you can run the panels in two parallel strings but there's a performance/cost penalty. The higher voltage string will run at the same voltage as the lower string, meaning your only at about 90% of full output on the higher voltage string. A string of 4 panels at 235 watts each is 940 watts; 10% is 94 watts. At $2/watt that's $188 worth of PV panel that's unused. It might make sense to get another controller except an MPPT controller rated for 940w at 120V is around $450.

Bruce

[OverTheTopCargoTrailer]

Hey Hey Bruce

You are now the go to SOLAR GUY for this form

You are the first guy to give me a 1/2 ass good reason to go to a second charge controller ....
Since my 4 panels are laying flat on the roof & 4 new panels would be installed Vertical on the side wall my best guess was that I would only pull 50% anyway
The flat roof panels get supper dirty, REALLY FAST and need cleaning every week if you want max output ?
I would guess that at max / best case I would see 900-1000 watts ? I can experiment around a little.
Im guessing if it did not quite pull the power I needed or expected - then I would need to make some brackets to allow me to tilt the panels
If I went to colorado - then I would disconnect some panels so I would not overload the system.

I sorta like this Magnum MM1512AE Inverter and think it would do the job running the 500-800 watt window ac , the newer model has been upgraded from 1200 to 1500 watts now...
Im checking to see if the free remote would also allow me to equalize the batteries ? Just got Answer is the mini remote does not
But they will give me a $50 credit for larger remote that costs $189

http://www.wholesalesolar.com/products.folder/inverter-folder/Magnum-MM1512AE.html


If I got another charge controller I sorta like the Midnight Solar charge controllers....
The Outback Flex80 is great, but you gotta be a friggin engineer to figure it out

http://www.wholesalesolar.com/controllers.html

Thanks for the help & ideas

[8ball_99]

So the plan is to have 2 strings of 4 panels that run on two different voltages so you will also need two solar controllers? The new panels will have to go on the wall of the trailer because of space reasons. So thats what thats adding another grand worth of panels plus another few hundred for a controller. All that to be able to run a AC a few hours a day I mean I understand your wanting an over the top cargo trailer.. But the four 210 Kyocera panels on a 7x16 is already a little out there. I would think you already have more power then you can really use. I understand wanting to run the AC. But doing all that just to be able to run it during the day for a few hours just doesn't seem very useful..