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Wednesday, November 30, 2011

A Better Solar Charging Mouse Trap.PART 4

    Welcome back! Can you believe we're at Part 4 of this article already? I've said it before, this all sounded so simple when I started!

OK. Onward we go. Let's talk about wires and wiring. Basic. Run wires from Panels to Charger, from Charger to Batteries.

Yeah, right!

While I have been known to cut the odd corner here and there, wiring should never be one of those corners. It is really important to select the right type and size (gauge) of wires for each wire run segment.

Click to Enlarge!
My install included connecting the Solar Panels, The MPPT Charge Controller, a large Inverter/Transfer Switch, several high amp switches, fuses for all lines, an Energy Monitoring system and a monitor/display for each device.

As you can see, this is a bit complex to look at. If we look at each segment separately, it becomes MUCH easier to digest.

First, we have to select the wires from the panels to the charge controller. Not too hard. The size is simply based upon the voltage, amps and distance. Here is a quick wire sizing calculator:
Voltage Calculator

Notice the heavier wires coming out of the fuse block.
Since these were to be partially outside, on the roof, they needed to be well insulated against weather and UV rays to keep them healthy for the long haul. I ended up with 8 AWG dual conductor marine duplex wire. It wasn't the least expensive, but was the most durable and came in white so it wouldn't absorb as much heat as a a black sleeved version. Looking back, I seriously over-sized the wires. I had forgotten i needed to run 3 individual runs. One set of two wires from each panel to the Charge Controller. These needed to go across the roof in a few places then down into the fridge vent, to a fuse panel then into the controller.

 Each Solar Panel had a junction box with screw terminals inside and a water-proof, well I always say water-RESISTANT wire pass through on the outside. I stripped back the duplex sleeve and the individual conductor's insulation, started to pass them through the pass through.....and found out they weren't going to fit through. Oh, great. Now What? Did you ever hear that if something isn't working, force it? If it breaks it needed fixing anyway? No? Well with a judicious amount of force and much cursing I managed to force the wires through and screw on the clamping nut. FYI: Make sure you put the nut over the wire BEFORE you insert it into the junction box. Don't ask how I know that.

So, now that we have the panels wired to the fuse block (1 fuse per panel) we have to wire the fuse block to the Charge Controller. I have 3 sets of positive and negative wires going IN to the fuse block and I wanted to have 2 (1 positive and 1 negative) coming out. This was easy. The fuse block gave me two large terminals to connect to and I used MUCH larger gauge wire to connect to the charge controller. The fuses are inline with the POSITIVE wiring from the panels and the NEGATIVE wires are tied together at a terminal on the fuse block. Since the wire run was very short (<1ft) I used some extra 2/0 AWG from the battery run.

**Warning Light Science Content!!**

     Why an MPPT Charge Controller? What the heck is it, what's it DO?!? 

Well, that's a good question. M.P.P.T stands for Maximum Power Point Tracking this is a fancy way of saying that it can figure out how many volts your panels are producing and convert it to more usable charging current (AMPS) when the Voltage exceeds what the battery needs to charge it. It's good for me, since I have panels that are around 36-44 Volts, I can start charging earlier in the day and longer into the afternoon/evening. Nothing is free, however, you cannot get more WATTS out of a panel than it will produce.At best, you can generate around 20% more charging during a given day. For me that was really important since I didn't have enough roof real estate to keep adding panels.

**End Science Content**

   So now we've got power to the controller! Yay!  What are we going to do with it? In PART 5 we will talk about Inverters, transfer switches, battery wiring and making the system co-exist with what you have now. Everything has to play nice together!

Until Next time,

Be Seeing You...Down the Road,

Rich "The Wanderman"

Read Part 6 of this series.
Read Part 5 of this series.
Read Part 3 of this series.
Read Part 2 of this series.
Read Part 1 of this series.


  1. excellent articles and thanks. eventually i will want a system like this installed. do you do installations or do you know someone who does?

  2. Anonymous,
    I'm not a professional installer, but depending where you are geographically, I'm available to help out. Advice is ALWAYS free :)

    Rich "The Wanderman"

  3. Totally enjoying your blog post about solaring up! We are already solared up and sooo enjoy the easy way to boondock and the peace and quiet of NO generators running. Our solaring up post is at: if you want to check it out.

  4. Took a look at your install. Beautiful work!

    Rich "The Wanderman"

  5. Would be more interesting if you got into what all of this cost as you went along...and a total price at the end.

  6. Kevin and Ruth,
    Stay tuned, the final part will go into the totals for all parts and materials.


    Rich "The Wanderman"


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