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Old 12-05-2019, 10:30 PM   #1
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Advantages and disadvantages of hooking solar controller directly to the 12v bus bar

I've not seen this talked about.

What are the advantages and disadvantages of hooking your solar controller output directly to the RV Bus bar since it has a connection to the batteries already?

Is there a reason why one should not do so?
To me it seems redundant to run another set of wires to the batteries when the controller is mounted inside the trailer.
Some of the current could be used to run the 12 volt stuff in the trailer as the batteries are in absorption phase

Is there a need to use the batteries to filter the current coming from the controller?

Or if it should not be done at all, Why?

Thank you,


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Old 12-05-2019, 11:36 PM   #2
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It doesn't matter

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Old 12-06-2019, 12:30 AM   #3
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That’s what the Airstream does with the roof mounted panels.
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Old 12-06-2019, 12:36 AM   #4
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Advantages and disadvantages of hooking solar controller directly to the 12v bus bar

My DIY solar system is correctly connected to the battery side of the use/store relay.

The idea of the solar controller and panels is not to power the trailer, it’s there to charge batteries.

In fact, if my MPPT controller is not connected directly to the batteries it’s output is zero.
Rich, KE4GNK/AE, Overkill Engineering Dept.
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Old 12-06-2019, 08:01 AM   #5
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My solar is connected to the busbars like diagrammed on page 8-17 of my Airstream's owners manual. Link: The solar connections are the large (6GA) orange wire and the large black wire at the bottom of the picture. The copper connections are Blackburn 6GA copper lugs: This connection method works perfectly and provides an easy connection point when your batteries are mounted in the Airstream tongue-mounted battery box.
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2018 Globetrotter 27Q, 32 nights 4,935 miles, 600W Solar, PD4655L, 6V Batteries, ProPride, 16" Michelin's, 2019 F250 PSD
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Old 12-06-2019, 10:10 AM   #6
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Since solar is free, it sort of does not matter what you do. The "stock" approach is to route it to the DC bus bar. There is no practical downside to doing this as long as you have fuses in the right locations.

The only exception would be if your solar puts out something like a hundred amps. The battery hooks to the bus through a 50A breaker ... You physically can't put enough panels on a 25' to get that sort of current so it's a non-issue in this case.

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Old 12-06-2019, 10:41 AM   #7
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you need a solar controller.

the battery voltage is constant
the solar panel voltage varies (based on dynamic sun levels)
The solar controller matches the two so that it can convert the solar output into something that the battery can take as input
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Old 12-07-2019, 02:10 AM   #8
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Thank you everybody, I've read a lot of posts here and they never talked about tying the controller to anything except to the batteries snd I being funny like I sm wondered is there a reason why it should not tie into the bus bar.

Thank you airmiles for answer with what to use.

Thanks again,

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