Installing Solar Panels on the Garage

The first set of solar panels is working so well that I decided to get another 30 panels and put them on the garage roof. The garage roof faces just south of west so there will be about a 20% decrease in power. The new panels, by coincidence are almost exactly 20% less expensive than the first set, and they offer a little more wattage, 215 watts each instead of 210 watts. The garage roof gets full sun all day from the instant the sun shines on it so it should be a good location for solar panels.

Since the first set of panels works, I didn't reinvent the wheel. I used aluminum and stainless steel hardware from Fazzio's to build the same support rails as I did the first time. I improved some of my techniques and I made some minor changes. See my first solar installation for details not provided below.

June 29, 2011

I ordered 30 215-watt Kyocera solar panels from Northern Arizona Wind and Sun. They still have the best prices for Kyocera panels.

July 12

Panels arrive. Here they are next to 12 20' pieces of square tube aluminum:

July 13

Time to start on the roof. I used the monster hacksaw to cut 3x4x2.25" aluminum angles to support the aluminum rails. I set up an old castor on some boards and bucket to support the long piece of 3x4x1/4 aluminum angle:

I marked the aluminum at 2.25" intervals and cut. I drilled the angles with the same jigs I used on the house project. Here is what an angle looks like mounted on the roof:

The angles must be mounted in a straight line using 4" lag bolts into the roof rafters. I had to find the rafters under the roof. I tried this:

I clamped a strong magnet to a rafter near where the first angle would go. Then I found the magnet with a bar magnet on the roof. From that reference point I measured over to where the center of the rafter should be:

OK, so I missed the rafter on the first try at about 1.25 inches from the magnet. The nail went firmly into the rafter on the second try at 2" from the magnet.

With a nail on each end of the roof, I ran a chalk line by attaching one end of the line to a nail:

Then I pulled the string out till it was tight and wrapped it around the nail at the other end. Snapping the line straight against the roof gave me a nice straight line the length of the future rail. You can see the blue string below the chalk line:

July 15. Here is the roof with many angles mounted at 4 foot intervals. The first rail is attached:

As I worked my way up the roof, I could sight down the installed angles using a piece of aluminum tube to get a good idea where the rafters were. Most of the time I hit the rafter on the first try. If I made a hole in the roof, I filled it with roofing cement. The hole usually ended up under the foot of the angle.

To help keep the angles lined up across the roof, I leveled the roof surface by adding pieces of scrap shingle as shims:

On the house roof, I drilled the mounting holes in the rails while working on the roof. It was difficult to drill straight holes with a cordless drill on the roof. On this project, I brought the rail up on the roof, measured the location of each hole at each angle, then took the rail down to drill it using the drill press. I needed only to open a garage window to get a clear path on the drill press:

I think this helped get a nice straight rail. No shims needed on the backs of the angles:

July 21. Five rails up, bolted, spliced together:

July 24. I needed a better way to drill holes in the rails for the solar panels. I decided to weld an iron template using a solar panel as a guide. The template will have holes drilled in it to match the mounting holes on the panels. I will be able to clamp the template to the rails and drill four holes in the right locations. Here is the template before welding. It is positioned over a solar panel using 3/8" bolts as pins to hold it in place while it is clamped together:

Here is some detail to show one of the drilling holes. The bolt is in the drilling hole. The adjacent hole will show me where to drill the hole for the next panel:

This template will allow me to quickly drill the mounting holes in the right places and it should result in correct spacing between panels. I should also be able to drill all the holes in a row in one pass. This should speed up panel installation significantly.

July 26. First panel up. I cobbled together a sturdy platform for the roof of the van out of the solar panel pallets, a sheet of plywood and a couple of 2x4's. Makes a nice movable scaffold:

July 29. Eleven panels up. Is the template working? Yeah, baby!

I ran a #10 solid copper ground wire to each top panel as I did on the house panels. I connected the top row of panels together in series by snapping the panel MC4 connectors together, then checked the voltage across them in the late afternoon using a voltmeter:

274 volts. That's right.

View to the North:

In this picture, you can see the 4" 5/16" carriage bolts as posts on the rail below the panels. They will hold aluminum blocks as explained below.

August 1. 20 panels!

The second row panels are secured at the top by 2" square aluminum blocks on threaded posts. Here they are cut by the monster:

As the monster was cutting a block, I was drilling a block at the drill press:

You can see the blocks held down on their posts with a lock washer and a nut. I dabbed the posts with thread locking compound before I tightened the nuts.

I need two 15-panel strings. I will wire them this way:

At this point I could see that I would need one 15-foot extension cable for the long blue line, and a longer one for the red line that would also go down the north wall to the inverter. I will also need two 20' cables to attach the blue string to the inverter. I ordered one 15' cable and two 50' extension cables from Northern Arizona. The 50' cables will be cut to connect the ends of the strings to the inverter.

August 3 and 4. I ran more ground wire and drilled holes for the last row. The cables arrived from Arizona so I was able to run the long red line and connect the blue line in the second row.

August 6. 29 panels up:

I have to get the cables all sorted out before I can put up the last panel. Here is a view from a stand of spruce trees in the back yard:

I made a conduit clamp from a piece of aluminum angle, belt sanded it to give it a nice brushed finish:

August 8. I chose 1" PVC conduit to route the cables from the roof to the inverter:

I mounted the clamp and secured the conduit in place:

I carefully measured the extension cables and cut them so that the ends of each string would reach the future inverter. I had cable to spare for all the wires except the white ground wire which should just reach the ground terminal in the inverter. I stuffed the wires in, four DC cables and two ground wires:

I carefully labeled the end of each cable as I put it through the conduit so that I would know its polarity and which string it came from, top or bottom:

Cables sorted out. I will leave a break in each string of panels so that the panels are not "live." I don't want anyone, like me for example, grabbing the cable ends when there are 400 volts DC across them.

Ready for the last panel. Done:

I need only run the ground wire to a few panels on the bottom row and connect the lower panels together. I'm ready for the inverter, not ordered yet :-(

August 9. I finished running the ground wire to the panels on the bottom row and I connected all the MC4 cables except one, to leave the bottom string open.

August 10. I ordered the inverter.

August 12. I have to figure out how to get the wires from the inverter to the subpanel in the garage. Here is the subpanel:

Inside you can see a double space open on the lower left. This will hold a double 40-amp breaker:

I will run the inverter AC wires along the wall in a conduit but I will have to feed the wires into the panel at the bottom through one of the knockout holes. I will cut a "service panel" in the wall marked out in the picture below:

August 13. To accurately measure the length of wire I will need for the conduit, I had to have a good idea where the inverter will go. I added the vertical piece of PVC conduit outside and I put the wires through a 90 degree bend with a connector to the inverter. And I got to draw on the wall:

I estimated the approximate position of the knockout hole in the back of the inverter (from a diagram in the manual), went inside and marked the wall. Then I used a tape measure to approximate the distance from the mark on the wall to the subpanel through an imaginary conduit. To allow for error, I'll get 30 feet of wire.

August 17. Here the "service panel" is removed:

A close up of the knock out hole with a clamp in it. The wires from the inverter will go through this clamp, to meet electrical code:

Here is the first leg of the conduit that will go over to the inverter. The piece at the top of the conduit is called a pull 90, a 90 degree angle with easy access to the wires that will go through it:

Now I have to wait for the inverter because I didn't know the exact location of the knock out holes in the back of the inverter.

August 19. The building inspector came this morning, asked a few questions about the installation of the panels, then approved the installation.

September 9. The inverter finally arrived! It was back ordered, it was delayed by a hurricane, it was delayed by what-EV-er.

September 10. I cleared the path to lay out the conduit:

I measured the position of the knock out I will use on the back of the inverter, drilled a hole in the wall and mounted the inverter bracket:

I put a short piece of conduit through the wall, packed around it with duct seal (electrician's clay) and attached the lower section of the inverter to the bracket:

In the garage, the conduit sticks out too far:

I cut it off with a little hacksaw:


Then I ran the rest of the conduit:

At the inverter end, I stuffed four colored #8 wires into the conduit. I used a pull 90 elbow at this end of the conduit also:

The insulation around this wire is very slippery. I was able to easily push it through the conduit to the other end. Here it is coming out at the sub panel:

I pushed the wires through the wall into the inverter:

Pulled them tight from the other side... pull 90:

I connected the DC wires from the solar panels after pulling them into the inverter and cutting them to the appropriate length. I labeled them first to keep everything straight:

All four DC wires connected:

After wiring each string, I went up on the roof to close each string by making the last connections. I checked the voltage of the top string:

And the bottom string:

Close enough!

I connected the AC wires from the sub panel:

Then I wired the sub panel:

I will use the 40-amp breaker for the AC disconnect. Hopefully the inspectors will approve.

I attached the upper section of the inverter and turned everything on. I got the correct start up sequence on the inverter, but the sun was too low to yield sufficient DC voltage to provide solar power :-(

Here is the inverter installed:

I'll try it out tomorrow.

September 12. I turned the power on three times yesterday to test the inverter. In the early morning, the garage was putting out about 150 W, like the house inverter. Mid morning, the house was putting out 5000 W while the garage was doing 3000 W. In the afternoon, the house was down to 2000 W and the garage was up to 4000 W. Working. I'll call for an electrical inspection today. Time, the inverter readout and the electric bills will tell me how the garage system will perform.

September 13. Before the electrical inspector comes, I should secure the conduit from the roof to the inverter by clamping it to the wall. The conduit is not against the wall due to the large radius of the 90 degree angle bend from the roof to the wall. I made a stand-off clamp from a conduit hanger from Home Depot, a piece of aluminum and some stainless hardware:

I made two of these, drilled holes in the aluminum plate and mounted the clamps on the wall with galvanized screws:

Very solid. Hope the inspector approves.

September 19. The inspector came, approved the hook up to the sub panel. He signed the Electrical Inspection section of the Agreement Form for the power company. I emailed the power company with the signed Agreement Form attached. Now I have to wait for power company approval to switch on the new panels.

September 20. I screwed on the sub panel cover, installed a plastic safety shield in the inverter, closed it and screwed down the inverter access cover.

The mechanical and electrical installation is complete except for turning the ON switch!

September 30, 2011. I got approval from the power company to turn the switch, though not until late afternoon. I turned it on anyway.

October 1, 2011. First watts after approval, at 7 AM or so:

I'll keep an eye on the two solar panel systems, to make sure they know how to play with each other. I have to complete an As-Built Technical Worksheet to apply for an SREC number, but the physical installation is complete.

Here is Orion rising over the garage:

October 2011