OverTheTopCargoTrailer 7 x 16

[bdosborn]

What kind of controller do you have again? Was it a Morningstar?

Bruce

[OverTheTopCargoTrailer]

I have a single Flexmax 80 charge controller ....
It will do 1250 watts at up to 150 volts - output max 80 amps

keep in mind not all 1530 would be on line, only maybe early mornings or late afternoon....
besides all panels are not at the best angle to the sun
so that I will not overload or blowup charge controller

More wiring details are on the blog

http://overthetopcargotrailer.blogspot.com/

[bdosborn]

Outback! That's right, I knew you had a good controller. Let me do some reading and I'll get back to you....
Bruce

[bdosborn]

I did some reading of the Outback manual and I think you're on the right track with the 3 strings of two panels in series. Each string will be at 60V, which is well below the 150V max of the controller. You've got the panels on the sides as a separate string so you won't have any weird shading issues by mixing side and top panels. You're pushing the input capacity with 1530 watts but I don't think it will be a problem since most of the panels will be laying flat anyways. I doubt you'll ever see full output of all the panels and the controller will just "clip" its output to 80 amps if you do. I have a hard time going over 80% of my 220 watt capacity without tilting the panels; I've only seen full output on the summer solstice when it was cool outside and I was at 9,000 ft. (btw, it was very cool to see my controller maxed out at 14.99 amps )

You'll need fuses on each string since you have more than two. Your string fuse size it too small at 10 amps, NEC would require a minimum 15 amp fuse/wire. I would try to find 20 amp circuit breakers from the home center that's rated for DC. I think Square D has some and Midnight Solar has some nice ones you can get off the internet. Voltage drop isn't a problem, you can go 30' with a 1.8% voltage drop on a #12 awg wire. I would use #12 awg wire from the strings to the circuit breakers/bus, than a #8 awg from the bus to the controller. Make sure you use the right kind of wire to the strings, I would buy Solarline 2 extension cables with preinstalled MC4 connectors on them rather than using el cheapo automotive wire.

Don't undersize the wire from the controller to the battery, Outback recommends a #4, I would go with a #2. I think you already have a fuse at the battery, which is good.

Bruce

[OverTheTopCargoTrailer]

Hi Bruce

thanks for advive ....since NEC is not checking my work why not use 10 amp dc breakers vs. 15 on each string - they would trip sooner ?
right now I have all 4 panels 210 x 4 @ 100 volts on a single 15 amp dc breaker
the midnight solar breakers are only $12 - cheap

Right now I have a 63 amp dc breaker from charge controller to the the Battery - I'm looking for a 80 but its harder to find ...
I purchased a Blue sea 80 amp breaker ( $59 - ouch ) that is easy to open & reset - that is my plan "B"

http://bluesea.com/category/3/10/productline/overview/433

My out back wire is # 2 or 4 AWG and is only 2 ft long to the main bus bar... from there it is # 1 AWG - 4 ft more to the batteries.
# 2 marine stranded wire at 90 deg rating can pull 130 amps over 13 ft distance.

I now have a 150 amp fuse at the batteries - since I blew the 75 testing the ac

the MC4 wires are all # 10 and my runs are all supper short under 3- 6 ft each ...( the LG panels leads now actually have # 12 wire )
I was surprised to see 670 watts from my 4 x 210 panels , laying flat at 1:30 pm last week, max NOCT is 149 watts per panel = 596 watts normal max
when its FREEZING cold then the output goes up on the panels.

Psssssssst ....no wire on my trailer is el chepo .....they are all oversized & under fused
after all if it would burn down - I'll need to start over - its not like I can buy a new model OTTCT
down the street.

thanks again


P.S. so opening the panel breakers under load would not be a problem ?
as its written never disconnect MC4 panel connectors under load

[bdosborn]

Hi Bruce

thanks for advive ....since NEC is not checking my work why not use 10 amp dc breakers vs. 15 on each string - they would trip sooner ?
right now I have all 4 panels 210 x 4 @ 100 volts on a single 15 amp dc breaker
the midnight solar breakers are only $12 - cheap

The circuit breaker is there to protect the wire, not the panel. A #12 will is rated for 20 amps and will carry 20 amps forever, hence the 20 amp breaker. Remember that there will be times when the current may be higher than the panel rated output so you need to size everything higher than Imp of the panel. Also, molded case circuit breakers will trip at a lower current levels than the rated value when they're clustered together in a breaker box. They have a bimetallic strip in them that trips the breaker when it gets to a certain temperature, which depends on the load that's running through it. The breaker runs hotter when its bunched together with other breakers in a closed box. 80% is the typical rating the manufacturer recommends loading them to when they're not in free air.

Right now I have a 63 amp dc breaker from charge controller to the the Battery - I'm looking for a 80 but its harder to find ...
I purchased a Blue sea 80 amp breaker ( $59 - ouch ) that is easy to open & reset - that is my plan "B"

http://bluesea.com/category/3/10/productline/overview/433

Here's a link to a relabeled Bussmann circuit breaker which, BTW the Blue Sea is as well. You don't want to use an 80 amp breaker as you'll trip at full output. I would go with a 100A breaker.

100A Circuit Breaker

My out back wire is # 2 or 4 AWG and is only 2 ft long to the main bus bar... from there it is # 1 AWG - 4 ft more to the batteries.
# 2 marine stranded wire at 90 deg rating can pull 130 amps over 13 ft distance.

You really should have a #2 wire if you're going to use a 100A circuit breaker

I now have a 150 amp fuse at the batteries - since I blew the 75 testing the ac

the MC4 wires are all # 10 and my runs are all supper short under 3- 6 ft each ...( the LG panels leads now actually have # 12 wire )
I was surprised to see 670 watts from my 4 x 210 panels , laying flat at 1:30 pm last week, max NOCT is 149 watts per panel = 596 watts normal max
when its FREEZING cold then the output goes up on the panels.

Psssssssst ....no wire on my trailer is el chepo .....they are all oversized & under fused
after all if it would burn down - I'll need to start over - its not like I can buy a new model OTTCT
down the street.

thanks again


P.S. so opening the panel breakers under load would not be a problem ?
as its written never disconnect MC4 panel connectors under load

Circuit breakers are typically rated for a limited number of operations under load. Check the specs of whatever you get.

[OverTheTopCargoTrailer]

Hi Bruce

After reading 3 times.... I figured out your talking about solar panel & at first I was thinking electric sub panel for some reason
I do know that breakers trip much sooner when hot - then when cold, including the air temperature & are generally rated at 25 deg C
I have never seen anything that says these breakers are good for X # of - resets
Generally all small breakers should get turned off first & the larger ones last...

ok so now I get why using 15 amp on the panels vs 10 amp breaker.....for the panels
I'm still a little foggy on why the Flexmax 80 - ( rated at max 80 amp output) should have a 100 amp breaker ??
I would think if I pull more then 80 amps for a short time - its more likely for the charge controller to get fried ?
so would it not be be safer for the equipment with a 80 amp vs a 100 amp ?
or we could split the difference and go for 90 amps

Thanks for the link on the other breakers....they are 60% cheaper then Blue Sea
I guess the only difference is the ignition protection ? as they don't mention that feature ?


I have seen a lot of fried wires in my time (( at peoples houses)) & with all the Insulated foam panel on board OTTCT ....
I have a little fear, if the thing goes up, it would be like a roman candle, I'm not even sure the extinguisher could put foam out
therefore i'm more into having 90 deg # 10 AWG wires on 15 amp breakers - just to be extra safe.

Im real good with ac - but that DC stuff is new to me & seams to allow more amps to be pulled faster

thanks for all the help


http://overthetopcargotrailer.blogspot.com/

[bdosborn]

ok so now I get why using 15 amp on the panels vs 10 amp breaker.....for the panels
I'm still a little foggy on why the Flexmax 80 - ( rated at max 80 amp output) should have a 100 amp breaker ??
I would think if I pull more then 80 amps for a short time - its more likely for the charge controller to get fried ?
so would it not be be safer for the equipment with a 80 amp vs a 100 amp ?
or we could split the difference and go for 90 amps

I would go with a 20 amp instead of the 15, remember the circuit breaker protects the wire, not the panel. Your wire is rated for 20 amps.

You won't be able to get the full 80 amps out of the controller if you use an 80 amp circuit breaker, it will trip when you get to full output. Once again, the circuit breaker protects the *wire*, not the controller. That's why I would use #2 wire on the output as its good for 100 amps. The controller has its own overcurrent protection built into it. You could use a 90 amp but I would use a 100 since you shouldn't load a circuit breaker of 80%.

Bruce

[OverTheTopCargoTrailer]

a breaker.png (105.7 KiB) Viewed 5412 times

Hey Bruce

More electrical questions.... ??
I noticed on these DC breakers one should put the power connected to the "off" side of the breaker switch & the "load side" - should be on the on switch side ?
This can be confusing at times, especially when wiring the charge controller "load side" - that sends power to the battery.

Does the breaker still work if an overload comes from the other direction ? Is that even possible ?
I also read that fuses under load should not be used as a disconnect as this will also cause dangerous arching ?
any ideas on that subject are helpful

thanks Jerry

http://overthetopcargotrailer.blogspot.com/

[OverTheTopCargoTrailer]

Bruce

Are you on vacation

Any thoughts on the last post about the breakers ?

[bdosborn]

Bruce

Are you on vacation

Yup, I've been camping....

It's harder to find a breaker that's bidirectional but they are out there. I'd be surprised if the Midnight solar breakers aren't bidirectional. I would make sure you follow the recommendation of whatever breaker you're using and orient it as required. The breaker may not operate if current is flowing the wrong way through it. It's a pretty common problem on new grid tie PV installations at existing buildings; the electrical inspector shows up and points out that the existing breakers the new PV system is connected to aren't rated for current flowing backwards to the utility.

Circuit breakers have arc chutes built into them that extinguish any arc drawn when they're opened. Fuses don't have anything like that so you can draw a pretty big arc when you're pumping 80 amps at 60 volts and you try and pull a fuse out.

Bruce

[OverTheTopCargoTrailer]

Hi Bruce

I was very careful to always hook the wire "load side" to the bottom + side or "off side" of the breaker, because I figured why else would the "+" be there.....
Its a little confusing between the panels, charge controller and the Inverter
the first 2 are making power & the inverter is just converting power from the battery....so the battery goes on the "+" side
So I am just talking about DC breakers...... none of my power goes back to the grid

I would assume ac breakers flow in both directions , as that is what ac does 60 x a second.


I just got a little worried reading this junk : where a solar panel caught fire

http://www.wind-sun.com/ForumVB/showthread.php?4524-Panel-Fire-Question

As to FUSES and breakers I always try to shut off the LOAD first , no matter what....so that is a good tip to keep in mind about how they arc.
Circuit breakers have arc chutes built into them that extinguish any arc drawn when they're opened.
Fuses don't have anything like that so you can draw a pretty big arc when you're pumping 80 amps at 60 volts and you try and pull a fuse out.

Thanks Jerry

P.S. below is a good story about how the Rate payers will get screwed again when it comes to solar
they will end up paying 50% more for their green power, 13 to 20 cents per KW is what the solar panel co gets....
NICE deal.... why cant little people get in on a sweet deal like that ??


http://www.latimes.com/news/local/la-me-bigsolar-20120921,0,4991127,full.story

[OverTheTopCargoTrailer]

I'm in the process of writing the Factory to see if they will build a new trailer, OTTCT 2.0
this design is needed to Hold the 1,530 watt solar panels and 1,200 AMP hour batteries
it will also have Tandem Dexter 6,000 or 7,000 Axels to hold 12-14,000 lbs GVR

here are some quick views of the coming design from Sketchup

A new trailer view.png (140.91 KiB) Viewed 5178 times

a Rear Cargo door.png (102.36 KiB) Viewed 5178 times

as always you can see some more details on my blog


http://overthetopcargotrailer.blogspot.com/

[OverTheTopCargoTrailer]

Hey Guys

I have not had any luck hearing back from Lark after 10 days to my inquiry about building a new unit ?
I guess trailer building business is too good, to bother with someone who wants something special for only $10k

I have been doing lots research on all the trailer parts, I think I can find just about anything from side panels to frames & posts etc

I had a idea - lets see what you guys think ? Since I do not have any windows
I was thinking to install a hatch cover into the top of the fold down cargo door, the area above my bed.
like 36" wide x 24" high -- http://www.hatchlift.com/rv-hatch-gallery.aspx
On top of that I wanted to Install a rear solar panel- so it appears panel is attached to cargo door,
In real life however the solar panel can be tilted up & act as hidden tilt up window or rear excape hatch
This could also be done on the side windows & solar panels used a shades

I also researched Dexter Axels & talked to factory reps....
Best Axel with the smoothes ride is loaded 80-90% of max rating,
22.5 deg neg , Easy Lube, Never adjust Elec breaks
cost about $498 per axel + $150 shipping for both.
Its a little tricky to weld axels brackets to frames - everything is supposed to be within 1/8"
Local dealer wanted $1.8K for the axels & $840 labor to install at $105 per hour. INSANE

Still trying to decide if I should get new unit 8.5 x 18 or to rip the
current 7 x 16 apart and start from scratch - with Dexter Torsion & BETTER Insulation....
each plan has pros and cons
Saw a supper tricked out Cargomate today but only 8.5 x 16 - only $6300 in California - not bad price
Picture is here- the 3 one down , with all chrome & LED lights on the rear door

P.S. I also say flexible white textured wall panels at Lowes .090 thick for $20-30 size 4' x 8'
these would be great to cover your walls or ceiling.
$200 to $300 would do an entire trailer- also moisture proof.

http://overthetopcargotrailer.blogspot.com/



Jerry

[8ball_99]

Wow your already going to replace your trailer. Have you even camped in it yet? You would be better off to order a trailer the size you need vs trying build one from scratch. I've got a pretty decent shop, welder, horizontal bandsaw, ect. Even doing it all my self its not really worth it. Paying a welding shop to build you a frame and mount the axles would cost more then just buying one. Factories buy the material in bulk and they have jigs setup already for the frames, axle mounts, ect. Now if you just want to do most of it your self you can buy just the blank trailer frames with axles from places.. My dad has built several catering trailers this way. He gets the frames and axles built to his specs and adds his own walls, ceilings and doors. Again for what they pay for the metal and axles its hard to justify building it your self for what little it saves.

Freedom trailers built mine.. They will do what ever framing, doors and axles you want. Over all I'm happy with the two trailers I've bought from them. The quality is good for the price you pay.

Also FWIW a 8.5x16 trailer is ok for a tundra.. If your weight gets up to what your talking about though it will be a bit much for that Truck. I've got a 2008 5.7L Tundra and it pulls pretty good. But the rear axle really limits its safe tow rating. Your not going to want your trailer to weigh more then 7-8k loaded. I wouldn't think it would weigh that much but when you said you wanted 6 or 7k tandem axles thought it would be worth noting thats to much for your tow vehicle..