Solar Component Selection 1120W System

[MNtal]

It doesn't matter if you rig the PV in parallel or series, and it doesn't matter if you run your battery bank at 12v or 24v...the MPPT is gonna stuff the same watt*hours into your battery either way.
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If your truck has a 12v chassis electrical system, then I'd rig the house battery bank to 12v...
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I'd rig the PV array in parallel because either way, the Vmp is high enough for battery charging, and rigged in parallel is redundant. Use a 4 breaker disconnect/combiner from Midnite and if one module craps out or eats a tree branch and gets broken, just flip the disconnect for that one module and keep on truckin' with 3 modules.

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dwh ~ This is the explanation I was looking for. :clapping: You sir deserve a beer, someone get that man a beer; thank you.
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Idasho ~ Reading back I understand better what you where getting at.
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My truck is a 12V chassis and so is the module, keeping the house batteries in 12V makes things simpler but do I lose any efficiency with my appliances running them with 12V power vs. 24V power?
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In parallel the system produces (Magic Land) 31.2V@36.28A
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or Parallel with 2 panels in series = 62.4V@18.14A
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All of which are 1120W but provide redundancy and will charge the 12V or 24V Battery bank.

 

[dwh]

You're welcome.

No, you won't lose efficiency. Oh, maybe a decimal point or two, which is enough to give the techno-weenie guys on the solar forum fits, but not enough to matter in the real world for a flat mounted portable rig.

(And for the record, I'm one of those techno-weenies when I'm on the solar forums and running the numbers for a FBO.)

You do have to make sure the wire feeding any heavily loaded circuits is big enough to keep voltage drop within acceptable limits. And of course, at 12v that wire will have to be about twice as thick as it would have to be at 24v.

Those numbers at the bottom of your post show the inputs to the controller. Now redo them using battery voltages to calculate the amps "boost" you'll see as a result of the voltage conversion.

If you get it right, buy yourself a beer and we'll call it even.

 

[dwh]

And for the record, "module" means "solar panel", not "charge controller".

 

[IdaSHO]

Unless you are dead set on 24V appliances, I see no reason to even consider a 24V bank if the chassis is 12V.

24V array, 12V bank and loads. Done.

Later on, if you find yourself wanting a 24V appliance, that's a simple matter of a small step up converter.

 

[MNtal]

And for the record, "module" means "solar panel", not "charge controller".

Module when talking Ambulance means the 14' box on the back.

 

[dwh]

Module when talking Ambulance means the 14' box on the back.

Now you're getting all NASA on me. Next you'll be talking about extravehicular activities and ********.

 

[rossvtaylor]

Which Model did you purchase? 150-SL or 200-SL or other
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Their naming convention kinda erks me.

We got the 150 Classic, shown in a pic on this thread page: http://www.expeditionportal.com/for...-Freightliner-ambulance-to-RV-we-hope!/page23

Here's something which might help with your decision... Call Midnite and talk to them. You may get Robin (owner/founder) or Bob (his brother) or someone else... but, if you tell them what you're doing, they'll help you select the right controller. And, they'll probably have some good advise on string configuration and other stuff to go with the good advice in this thread.

And, because I can't resist... we're putting three modules on top of our module.

 

[MNtal]

No, you won't lose efficiency. Oh, maybe a decimal point or two... flat mounted portable rig. (And for the record, I'm one of those techno-weenies when I'm on the solar forums and running the numbers for a FBO.)
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FBO???
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I plan to build a tilting rig for the panels and incorporate it into my party deck, a system could be built from 80-20 with electric, air, or manual actuators, seems pretty straight forward and worth the minimal effort.
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I'm a Machinist, Toolmaker, Tool Designer with experience in the Aerospace, Medical, DOD, Fiber Optic, Semi-conductor, and other Manufacturing Industries. Decimal places can mean a lot some times and other times not so much
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You do have to make sure the wire feeding any heavily loaded circuits is big enough to keep voltage drop within acceptable limits. And of course, at 12v that wire will have to be about twice as thick as it would have to be at 24v.
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Voltage Drop Calculator there's an App for that...
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Those numbers at the bottom of your post show the inputs to the controller. Now redo them using battery voltages to calculate the amps "boost" you'll see as a result of the voltage conversion.
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If you get it right, buy yourself a beer and we'll call it even.

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For the record, I'm going to buy myself a beer either way.
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Parallel System @ (Magic Land) = 1120W / 12V = 93.34A
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(@Panel) Module @ (Magic Land) = 280W / 12V = 23.33A
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Unless you are dead set on 24V appliances, I see no reason to even consider a 24V bank if the chassis is 12V.

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Remember I had a disclaimer in the first post about how this thread may end up. I also have a middle school level understanding of electricity.
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The appliances I currently own are rated for 12 or 24V but it sounds like I'll be better served with a 12V battery bank as my appliances are DC with fairly high EER.
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Conversions can equal 5-15% Loss.

 

[dwh]

FBO = Fixed Base Operation.

For actuators, look at electric gates, lotta gates run on 12vdc.

 

[loonwheeler]

In consideration of shadow effects on the panels, it makes sense to run all of your 24V panels in parallel configuration. Campers running voltages above 24V doesn't make a lot of sense for the (relatively) short runs of wire from to roof to the house charge controller and batteries.

If the chassis is a 12V system, I would also recommend running the same voltage on the house system. You can combine the chassis to the house system as a backup using a smart relay much easier provided they are at the same voltage. As far as I can tell, there is no major advantage to running the house system at a different voltage unless you are really concerned about wiring costs. I assume for your camper the costs savings would be fairly negligible.

Just my 2c.

 

[MNtal]

On the topic of batteries, I'm looking at these but can anyone make any good recommendations?
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Discover batteries @$400
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[GeoRoss]

Be careful running your panels in series. If you are running with the Outback Flex 60, it has a max 150V load IIRC. In cold weather it is possible for your voltages to trigger a shut down. It has been reported to me by a local installer that the Flex 60 can shut down at voltages between 135-140V.

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If 4 of My panels (1120W) are in series, I'm theoretically running them PEAK (Magic Land) 124.8V@9.06A to the controller.
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The controller takes that 124.8V and drops it down to 24V for the battery bank but in doing so increases the amperage by the same factor so it doesn't lose any power. (MPPT vs. PWM)
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124.8V / 24V = a factor of 5.2
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5.2 x 9.06A = 24V@47.A = 1120W
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(Please excuse the rounding errors)
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But more realistically in the (Real World), where we live, breath, and things don't always work out exactly as planned. I'm looking at 55%-85% output @62.4V-106.V going to the controller.
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Doesn't it make more sense to run a 24 Volt system? Forgive me, I'm from the North where kinda slow up-der-ya-know. (serious question, I really don't know)
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Where I live and where the System will be primarily used it has a potential for 4.0-6.0 kilowatt hours (Kw/H) per day, depending on which pretty picture you look at. I'm basing that estimate off of the pretty pictures on Google images, and the experience of the friend that sold me the panels.
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@ 55% Efficiency
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(1120W x .55 = 616W@25.67A)
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4.0 x 616W = 2464W
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2464W = 2.464 KW/H per day of charge produced by the panels at 55% efficiency.
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@85% = 3.808 KW/H per day of charge produced by the Panels.
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What are the down sides to running a system in 24V vs. 12V?.
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