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Tuesday, December 6, 2011

A Better Solar Charging Mouse Trap.PART 5

Welcome back! Now that we have things more or less hooked up it's time to get some power to the batteries and run our stuff without melting everything!

Old Inverter Installation.
Since the Solar Charge Controller is designed to charge our house (and chassis) batteries we need to get the juice to flow to them. This is where the biggest wires will be found. If the max output of the charge controller is 45 AMPS then you should size the wires for at least 20% more than that to be safe and efficient. I COULD have done that and been pretty much done at this point. But Noooooo! I had to try and be slick and add an Inverter to the mix. Inverters are nifty. They take your DC batteries output and turn it into good old fashioned house AC. No generator needed. Of course, it won't run EVERYTHING,  all the time. And forget the A/C, not going to happen on your typical 2-4 house battery setup. At least not for very long! Originally, I had the inverter wired up on a piece of wood directly to the battery. I did have a big switch and a "catastrophe" fuse protecting it. I believed I was a genius since I had managed to wire the inverter to power all the outlets along the passenger side of the coach and setup my AC fuse panel to work this out. The 1800W Inverter that I have also has an AC transfer switch in it. Simply, it allows AC power to flow through it to my passenger side outlets when I am on shore power or the generator.

I'm an idiot. This works, but has a lot of issues. Number one being I had no idea how much power I was using! If I didn't switch off the inverter I would kill the batteries. D'OH! Back to the drawing board. I wanted it to work essentially the same way, but have my energy monitor keep track of its power use. I also wanted a more compact installation.
MPPT Charge Controller (L) - Inverter (R)

Here's what I came up with. works!
It was a bit counter-intuitive. The controller's NEGATIVE is wired to the INVERTER negative then on through the SHUNT. This let's me monitor it's power use AND the power generated by the Solar Panels/Controller. Like a "Y" splice in a hose. I know...makes no sense....but's that how it works. The POSITIVE from the controller is wired into a heavy On/Off switch then on to ANOTHER Switch then straight to the HOUSE BATTERY compartment through a large Catastrophe  "T" fuse in a water resistant holder then on to the POSITIVE post. The POSITIVE from the INVERTER is wired to the SECOND switch. The trick was making sure EVERY load on the battery bank would go through the SHUNT and be measured by the Energy Monitor. Then, for safety every thing that uses power should have it's wiring protected by a separate fuse. All of this was very confusing when I first began to figure it all out. Eventually, I got my head around it. You will too, I promise. If you get stuck, drop me a line...I can help.
Click To Enlarge. Shunt is on the Right.
Charge Controller Display/Inverter Remote

To Monitor all of this gear I installed the optional remote control for the charge controller below the remote control for the inverter. The other white box in the picture is for the satellite dish. It tells the elevation so you can aim the dish. The small Black box is the inverter remote. it reads out voltage of the battery and allows the inverter to be put into standby. I have the Energy Monitor Display mounted into the front dash area. It was already installed when I purchased the RV and would be a HUGE P.I.T.A. to relocate!

In the final Part of this article (Part 6!) I will go over the costs, operating the system, the ups and downs of battery charging from Solar and what you can expect. It's been a long ride, but the benefits certainly outweigh the hassle! Hopefully, this series will have helped out a bit.

Be Seeing You...Down the Road,

Rich "The Wanderman"

Read Part 6 of this series.
Read Part 4 of this series.
Read Part 3 of this series.
Read Part 2 of this series.
Read Part 1 of this series.


  1. awesome stuff, been following from the begining, but I did try to click the link to see part 4 (somehow I must have missed it) and its not working. Wondering if you can fix that, I don't want to miss out on any of this. Looking forward to the completion and how well its working for you. Thanks!

  2. Ooops! Had a little typo there. All fixed now.


    Rich "The Wanderman"

  3. i need a wireing digram for installing 6 100 watt panels (12v) 36v to combiner box and then 36v to charge controller then 12v to batt i may later go with 2 more panels then i could go 48v to combiner box any help wold be greatly appreciated thx

  4. That's relatively easy. Wire the panels in 2 series of 3 panels "nose to tail". Then into the combiner box. Make sure the wires and fusing you use for the box to charge controller are large enough to carry both the voltages and the amps from the panels. Both now and later. Also make sure your charge controller will take varying voltages!

    Rick "The Wanderman"

  5. I think that solar is great and if the cost drops some more i will again look at the upfront cost again, As for some of the issues you were having as i understand them, why did you not use any isolators or capacitors for electric control ( not trying to tell you how to do you job just asking)?

  6. bsmi,
    The Batteries do have isolators from various charging sources. As for capacitors..not sure what you mean? There aren't all that great for storing long drain current, and can be quite dangerous when charged.

    The costs are coming down...figure 20-30% lower next year as manufacturers gear up to produce higher quantities. I have seen it drop from $3.50/watt to lower than $1.20/watt for conventional panels.

    Thanks for reading,

    Rich "The Wanderman"


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