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Author Topic: How to wire a pair of Solar panels  (Read 1023 times)

er78mph

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How to wire a pair of Solar panels
« on: December 31, 2016, 04:42:30 PM »
Hello and thanks all in advance.

I wanted to begin this post by letting you guys know that I am a eager newbie willing to put in work.  Not looking for shortcuts, simply looking for guidance in order to have piece of mind with the family.  I have learn so much over the last year and solar has humble me yet again. I will be buying a pair of 100 watt panels and have a ton of questions but I will limit them to maybe a few  ;D.  I have a 27 trailer that I like to dry camp with and would like not to depend on a generator.  Our energy use is not that much and would not be able to tell you actual numbers.  But with recent dry camping experiences with my 600 watt inverter and pair of 6v batteries, we've managed.   Energy use is mainly for tv, charging electronics, lights, water pump, slide-outs, and other low energy items. I have a pair of 6v batteries wired in series.  My question is how to wire the panels down to the batteries?  I know that there are shunts, fuses, charge controllers, and a battery monitor in my case.  I know fuse sizes depends on wire gauge and other variables but I would love a DIAGRAM to begin. I had a diagram drawn out with the panels, controller down to the battery but  I became confused with adding the battery monitor.  If someone could let me know where to place the battery monitor, that would be a great start!! Or better yet, a simple diagram to show me the order from the panels down to the battery would be AMAZING!  I will be attaching the renogy solar panels I am looking at, they have a detailed diagram, where would I put the battery monitor?  I also have a 600 watt in inverter in the mix wired directly to the batteries.   There are a bunch of diagrams but i would like a customized one to get me started.  Anything will help along with positive vibes ;D Thanks! And will hopefully hear from you guys at your earliest convenience!!

Additional questions-
would I have to wire the panels in series if my batteries are in series?
I dont have direct access to my batteries ( no vent pipes, or fridge vent, ect) the shortest route to the batteries seems to be running the wires on the outside.  Good idea?

here is what I am getting for my starter kit from Amazon



bayite DC 6.5-100V 0-100A LCD Display Digital Current Voltage Power Energy Meter Multimeter Ammeter Voltmeter with 100A Current Shunt by bayite

https://www.amazon.com/Renogy-Watts-Volts-Monocrystalline-Bundle/dp/B00B8L8MD2/ref=sr_1_2?ie=UTF8&qid=1483224043&sr=8-2&keywords=renogy+200+watt+solar+panel+kit






 

Paul & Ann

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    • Paul and Ann's Great RV Adventure
Re: How to wire a pair of Solar panels
« Reply #1 on: December 31, 2016, 04:55:21 PM »
On the Amazon link you posted, there was a diagram on how to install all the parts and pieces.  You can connect the panels in series if shading is not an issue.  The longer the distance from the panels to the controller the heavier wire you will need.  If you are going over 10 feet, I would suggest 4 AWG.
Paul & Ann  Iowa
2005 Winnebago Voyage 38J
http://stoughrvadventure.blogspot.com/

kdbgoat

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Re: How to wire a pair of Solar panels
« Reply #2 on: December 31, 2016, 05:17:40 PM »
Google "Jack Mayer"
I know you believe you understand what you think I said,
But I am not sure you realize what you heard is not what I meant


2016 Leprechaun 319DS

Dreamsend

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  • Posts: 158
Re: How to wire a pair of Solar panels
« Reply #3 on: December 31, 2016, 05:50:37 PM »
Do I get to say Welcome to the RV Forum Community!

You should Google "RV solar installation".  You'll finds many diagrams and explanations. 

Also, go directly to You Tube and search for the same thing.  Lots and lots of videos on the subject.  Here is one that by itself will not give you step by step instructions, but will explain many of the components.

https://m.youtube.com/watch?v=IgKSBs1ewh4

Also search this forum as many of your questions have been discussed here previously.

Linda
Linda with kitty Sarah
2017 Ford F250 Lariat aka Gypsy Rose

Lou Schneider

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Re: How to wire a pair of Solar panels
« Reply #4 on: January 01, 2017, 01:13:20 AM »
On the Amazon link you posted, there was a diagram on how to install all the parts and pieces.  You can connect the panels in series if shading is not an issue. 

Actually, that controller won't support series connected panels - it's designed for parallel connections.  The maximum input voltage from the panels is 25 volts and each panel is rated at 22.5 volts open circuit and 18.9 volts working voltage.  Parallel connections add current while the voltage stays the same as a single panel.  Series connections add voltage while keeping the current the same.  Put two panels in series and you'll exceed the controller's input voltage.

When you connect the two 6 volt batteries in series, you've made a single 12 volt battery out of them.   They'll charge just fine from the nominal 12 volt output coming from the controller.

The wire gauge from the panels to the controller is important, but more important is the gauge and length of the wiring from the panels controller to the batteries.  Mount the controller reasonably close to the batteries so there's not too much wire between them.

The battery charging voltage is set by the controller, and any voltage lost along the wires going to the batteries will reduce the charging rate as the batteries fill up.

The current shunt for the Bayite controller goes between the negative battery post and all of the wires connected to it.

One disadvantage of the Bayite is it only accumulates Amp-Hours in one direction.  You can measure how many amp-hours you're putting into the battery but not how many come out so it's of limited use to determine the battery's state of charge.

What you really want is an amp-hour meter that counts up and down, up when the battery is charging, down when it's delivering power.

Victron BMV 700

There's a different meter on Ebay, the 20 amp version with an internal shunt claims it will measure current and amp-hours in both directions, but that note is missing from the higher current models that use an external shunt.  I'm waiting for a reply from the seller about this, if the higher current ones also measure current in both directions they'll be a much better choice than the Bayite
« Last Edit: January 01, 2017, 11:37:21 AM by Lou Schneider »

Paul & Ann

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    • Paul and Ann's Great RV Adventure
Re: How to wire a pair of Solar panels
« Reply #5 on: January 01, 2017, 01:58:21 AM »
Thanks for the correction, Lou.  My math must be a little fuzzy today.
Paul & Ann  Iowa
2005 Winnebago Voyage 38J
http://stoughrvadventure.blogspot.com/

Kevin Means

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Re: How to wire a pair of Solar panels
« Reply #6 on: January 01, 2017, 11:06:09 AM »
The wire gauge from the panels to the controller is important, but more important is the gauge and length of the wiring from the panels to the batteries.
Lou, don't you mean that the gauge and length of the wiring from the controller to the batteries is more important?

For the OP... having a battery monitor that accurately measures amp-flow in and out of the batteries, so you can see at a glance what your battery's SOC is, is a VERY useful feature when boondocking. They're more expensive, but that's the feature we use and rely on the most when boondocking.

Kev
« Last Edit: January 01, 2017, 11:15:00 AM by Kevin Means »
2011 Winnebago Tour 42QD
Towing a Jeep Rubicon Unlimited LJ or an Acura MDX
RVI Brake 2, Minder TM-66 TPMS, 970 watts of solar
(Can't wait to spend more time RVing)
Lakeside, California

Lou Schneider

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Re: How to wire a pair of Solar panels
« Reply #7 on: January 01, 2017, 11:38:10 AM »
Absolutely right, Kevin. Thanks for the catch!

 

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