Connecting The Solar Panels To The Charge Controller


Initially I only had a few panels, making little current.  So I wired them up with 10 ga wire.  But as my system grows, it produces more power.  A short circuit test shows that my 225 Watt array can put out 14.4 Amps.  I could continue to use 10 ga wire, but the 25' run from the panels to the controller, would have significant losses.  It would be a shame to spend big money on solar panels, and have a portion of the energy wasted as heat in the wiring.  So as your system grows, be sure to upgrade the wiring as necessary. 

Below are a series of photos to give the uninitiated an idea of what's involved in such a project.  Not technically difficult, just takes a little free time and the desire.


Before you drill, make sure the hole won't hit a rafter.

The wiring from my solar array enters the attic by sneaking under the ridge vent end plug.  I wanted no connections that could be exposed to the elements.

Most of the goodies needed for the job.  The hole saw kit was under $10 at Harbor Freight.  The junction box and fittings came from Home Depot.

This sized hole saw was also the right size to drill the drywall.  More on that in a minute...

I fit checked the box to the wall.  Once I was satisfied with the orientation, I drilled the box.

The coupling was installed hand tight.

I mounted the box to the wall, and measured to the center of the coupling.  Now I knew how far to drill away from the wall.  I had already determined this location didn't have a rafter in the way.

I used my $19 Harbor Freight Sawzall to slice the 1.5" plastic conduit to length.  I made it a couple of inches longer than the distance between the coupling, and the ceiling.

Tuck the conduit up into the attic.

Then push the bottom end into the coupling.  Give it a slight twist to seat it, done.

Keep that drywall plug from the hole saw.  If you move and want to take your system with you, this plug can be easily put back in place, and since the texture matches the existing ceiling, it won't be noticeable with a dab of caulk in the joint.

I used my cordless shopvac to clean up the mess.

I terminated the 6 ga wire while still in the garage.  I then used a few tie wraps to make a loop on the end of the cables.  This gave me a good grab point with a Fish Stik.  Sure beats having to crawl across the rafters.

The wires easily pulled up into the attic.

I made a small bus bar for the panels to connect to.  Because the attic was still over 100 degrees, I used Anderson quick connectors.  Later I'll connect the panel wiring directly to the bars, reducing potential losses.

The 6 ga wire was connected to the bus bars, then added strain reliefs to the cables.

6 ga wire gets expensive.  This wire was recycled from another project, so I couldn't complain, but the black cable was too short.  Since I wanted to fuse this cable, the black wire volunteered.  I typically fuse the positive side.  Another scrap piece of wire was connected to the other side of the fuse block. Now it would reach the charge controller.  Problem solved.

These cables will eventually be encased inside flexible conduit.  This will be for aesthetics since the jacket on the 6 ga wire has a tough nylon sheath and jacket.

My small solar array doing it's part.

An honest 10+ Amps at the charge controller. 


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Last updated 10/28/08    All rights reserved.