Installing Solar Panels

August, 2009. I want to install a grid-tied photovoltaic solar panel system to lower our electric bill and to charge my electric car. New Jersey currently offers a $1.75 per watt rebate towards the installation of solar panels. Energy programs change from year to year. New Jersey's current renewable energy website (as of February 2010) is here:


I applied for the rebate in May and got my confirmation letter at the end of June. The panels must be installed, inspected and approved by June 2010 in order to receive the rebate.

Here is a good article called, "How do Solar Panels Work?"

The south-facing roof can hold 30 solar panels so it will accommodate a 6150-watt system based on Kyocera 205-watt panels:

(Update: I ended up getting 210-watt panels after a fortunate price drop.)

The township could not approve the installation of panels on the roof as it is now, because it has two layers of asphalt shingles. So when I submitted zoning and construction permit applications, I included reroofing the south facing roof as part of the construction permit. I received the permits on August 13.

August 18. I went to Fazzio's for aluminum rails and stainless steel (SS) hardware. Aluminum angles will be secured to the rafters with lag screws. The aluminum tube rails will support the solar panels. I based my design on solar panel installation manuals that I found on the internet. Here is a diagram showing some details of the grid support:

(Update: I ended up using larger angles to raise the panels higher off the roof. See below.)

Before I could pick up the aluminum, I had to make a roof rack for the van because the rails are 20 feet long:

The rack is simple but it did the job:

Square tube aluminum with 1/8" walls:

Here is the "old" roof:

August 19. I removed the gutter:

August 24. I borrowed a scaffold. I was giddy as I was putting it up. It will make the job much easier, having a stage to hold materials and tools. Also, it's fun to climb on:

I made drilling jigs to hold support angles so I can easily and quickly drill holes in the right places. This jig is for the 3/8" hole:

The angle slides in firmly, hitting a stop. The metal guide on top insures that the hole will be in the right place. Here is the drilled angle:

The angle with stainless steel hardware, a 2-inch long 3/8" bolt to hold the square tube aluminum, and a 4-inch long 5/16" lag screw into the rafters:

August 25. I tried out the shingle shovel, stripping off the top layer of shingles. This heavy flat blade shovel is great for prying up shingles and the nails that hold them down. This would not be too hard if it weren't for the current heat wave:

The aluminum flashing around sewer vent pipe is in great shape. I can reuse it:

I marked off the 12-foot length of 2 x 3 angle and used the monster to cut 20 2-inch wide angle support pieces:

It took this old machine about 30 seconds to cut a piece off. After the initial setup, I could drill a hole in one angle piece while the next one was being cut by the monster.

Here is a set of 20 angles. Close enough for government-subsidized solar panels:

The square tube rail will bolt to the angle with a stainless steel bolt, nut and lock washer, like in this test piece:

I ordered new shingles, trim board, drip edge and 4 rolls of Weather Watch, a peel-and-stick waterproof barrier that claims to seal around screws and nails.

August 26. I stripped a 3 to 4-foot wide section of shingles and tar paper off the roof. I also ripped off most of the trim:

I hammered a few nails into the plywood as some had lifted out when I removed the shingles. I also thought it could use a few more nails. When I ripped off the last piece of trim, I found that part of the 2x4 behind was water damaged. I will have to cut out the last 5 feet or so and replace it. I swept the roof and made sure there were no nail heads or staples protruding.

With the shingles removed, I was able to accurately measure the position of the rafters with respect to the edge of the roof. Now I can figure out the spacing of the support angles for the aluminum rails.

If I can easily remove the attic fan, I will have space for two more panels.

August 27. I cut out and removed the damaged 2x4:

I cut and nailed in a sturdy replacement:

My delivery arrived. The stuff below plus PVC trim boards and aluminum drip edge:

I installed the new trim boards:

And drip edge:

I put down the first row of Weather Watch. It's tar on a peel-and-stick sheet. You lay it down in the right place, then pull out the protective plastic from the back:

My son helped me unroll the unwieldy stuff to make sure it lay flat. Then I cut the tabs off several shingles and nailed them up as a starter course. My son and I were able to nail a few shingles on before dark. A time exposure:

You can see the starter course on the left at the ladder. We tried out a stapled tarp to prepare for rain, predicted for tomorrow afternoon. That's a firefly to the right of the scaffold.

August 28. Rain came sooner, showers in the morning. A stapled tarp is not good enough. I jammed it and other tarps under the old shingles, ready for more rain in the afternoon. I ran out of tarps, nailed some old tar paper up on the left. These coverings are doing a good job:

August 30. Roll up the tarps after the rain:

Nail on more shingles, lay down a 1.5' wide strip of Weather Watch:

That's as far as I can reach from the ladders and scaffold.

August 31. My daughter and I nailed down more shingles:

The new shingles are high enough to install the first aluminum rail. The first step is to drill 3/16" pilot holes into the rafters. To find the rafter under the shingles, I tried using a 4 foot level to extend a straight line down from nail heads in the exposed plywood, since these nails go into the rafters. I also measured 17.5" down from the exposed plywood edge, assuming that edge is parallel to the trim. This should give me a set of holes along a straight line. A pilot hole:

I put plenty of roofing cement under the angle:

I also tarred the lag screw:

Then I secured the angle firmly to the roof using a ratchet drive and socket:

Once the first pilot hole was drilled, I measured from it to find the next hole. This does not guarantee success as the rafters are not exactly 16" apart. Some are 15.5", others 16.5". I tried a stud finder but the "wood" setting could not find the wood rafters under the plywood. The metal setting found all the nails, including the many roofing nails under the shingles. Most of the time I hit a rafter on the first try. If I went through the plywood with the pilot drill bit, I squeezed some tar into the hole. The hole got covered by the metal angle so I don't think it will leak.

Here are several angles on the roof:

September 1. I bolted the first rails to the angles. I drilled the rails as it sat them place, a true custom installation. I varied slightly the vertical positions of the holes in the rails to make sure the rails were level:

Now I can use these rails as roof jacks to safely climb and work on the roof.

September 2. More shingles off. I will go high enough across the whole roof to lay two more rows of Weather Watch:

As I remove the old shingles, fine grit rains down over the new shingles. I taped some masking paper across them to keep the grit from getting trapped underneath them.

September 3. More shingles off:

September 4. More Weather Watch. September 5. More shingles:

September 6. Even more shingles, half done:

September 7. I put a strip of plastic sheet across the roof where the plywood is exposed, and mounted 10 more angles. Break for rain:

September 19. As I installed the rails, I could see that it would be difficult to reach under the rails to mount the panels. I decided to make new, taller angles. The tedious work of finding rafters, drilling pilot holes, drilling and leveling the rails was done, so exchanging the angles was not too difficult. I had to make new jigs to drill the new angles. It took me a sunny, cool Saturday to exchange all the angles. Here is a close up of a new angle in the foreground compared to the old angles in the back:

All rails higher:

September 20. I spliced the rails together in the center with a "splice," two 1/4" aluminum plates bolted to the two rails with 5/16" stainless steel bolts:

In the evening, I stripped off more shingles:

Like this:

September 24. I can only get up on the roof in my few spare moments. More shingles off; it's a good workout:

September 25. Ready for more Weather Watch, which I will have to get on soon, as rain threatens:

September 26. Two more rows of Weather Watch, leaving a narrow strip of exposed plywood:

I covered the plywood with the same strip of plastic sheet I used on September 7, then nailed more shingles. La pluie commence:

September 27. More shingles on. September 29. Screwed down more angles. September 30. Bolted on the fourth rail. October 4. Stripped off the rest of the old shingles. I had to pull the ridge cap shingles up (but not off) to remove the old roof shingles. I will replace these ridge shingles after I install all the rails:

October 10. Last Weather Watch and more shingles. I ran out of Weather Watch near the very end of the last course! I stapled a triple layer of tar paper down to cover the last couple feet of plywood. This should be fine since there will be no lag screws that far to the left:

I cut the Weather Watch to fit the hole under the exhaust fan. I trimmed shingles to fit the hole also. I slid the lower shingles under the fan flashing so rain will run off the flashing onto more shingles:

The next layer of shingles will just cover the flashing.

October 11. Shingles done, up to and under the ridge cap. I will recap the ridge after I have installed the last rails:

October 12. The 5th rail installed:

This 3D drawing shows how the 30 panels will fit on the roof:

October 21. The top rail on the left is installed. One more piece to go:

With the last rails going up, it was time to think about trimming the tree to the left of the roof. A few of its southern branches began shading the roof just after 2 PM. I thought about renting a high reach platform to operate on the branches with a chain saw, but I was willing to try other, cheaper options first. I ended up using one of the aluminum square tubes, strong and relatively light, with a bow saw duct taped to it. I was able to cut four large branches from the top left side of the roof. Here is a picture of two freshly cut branches shown by the red arrows. The red box shows the bow saw and square tube lying on the roof:

The roof is now shade free until after 4 PM.

October 25. Last rail on:

October 31. I ripped off the old ridge cap shingles and capped the ridge with new Golden Cedar 3-tab shingles. Each shingle is cut into 3 pieces. Each piece gets 2 2" roofing nails. I was able to sit comfortably on the top rail to cap the ridge. Much easier than straddling the ridge as I had to do on the garage.

November 1. I added a few 1/4" aluminum shims to some of the angles to straighten some of the aluminum rails.

The roof is ready for solar panels:

Since I will be installing a power system that will tie in to the public power grid, I had to apply to the electric company. I filled out a form specifying the size of my system, type of inverter, number of panels, like I had to do for my local permit. The electric company wanted a "one-line diagram" and site map also. After much research and study, I came up with this one-line diagram:

November 9. I came home to find two pallets in the driveway:

My son and I moved them two by two into the garage. The cats are as curious about them as I am:

I tested a few of the panels under fluorescent lights by connecting a voltmeter to the wires. Found voltage that varied as I tilted the panels towards and away from the lights.

November 15. First panel up:

I struggled with this first one. The panel didn't quite line up with the holes I drilled so I drilled them out more. I need a measuring method to better locate the position of the rail holes.

November 21. More panels up:

Here is a view under the top three panels on the left:

You can see one of the 2" 5/16" stainless bolts in the middle of the picture holding down one edge of the panel. The blurry head of another bolt pokes through the end of the rail on the left. Four bolts hold these panels. Very solid.

I tested each panel before installing it by connecting two old car headlights in series to the panel and lifting the panel to catch the sun's rays:

Before drilling more holes, I made a measuring tool from a piece of broken tape measure. I drilled a 3/8" hole at the 10" mark. A 3/8" bolt through this hole firmly holds the measure:

I drilled small holes in the tape measure at 37.1", 38.0" and 53.1" away from the bolt. These are the distances to the three other holes. This let me draw a sharp pencil line as a radius from the first hole. I did the same from the second hole, making X's at the other marks. This gave me accurate and square drill points for the rest of the panels across the top of the roof.

November 22. More panels up:

I had to shimmy along the ridge to get at the top bolts. It's OK. I built a garage.

November 26. Before I put up any more panels, I will run a copper ground wire to all the top panel frames. The panels are all solidly bolted to aluminum rails, but aluminum will oxidize over time and a ground fault could result. The panel manufacturer recommends using a copper ground wire attached to the aluminum panel frame with all stainless steel hardware, including a star washer to dig into the anodized aluminum. The panel vendor says to use #10 copper for the ground wire. This should be plenty for a system that will put out less than 15 amps of current. To prevent a galvanic reaction, the copper wire must not touch the aluminum frame. Here are the first two connections:

I put star washers on both sides of the frame. The connection, from top to bottom: bolt, star washer, panel frame, star washer, flat washer, copper ground wire, flat washer, lock washer, nut. As I went across, I stripped the insulation off the wire, made a loop, and bolted the wire to the frame:

November 27. The panels will be wired as two parallel strings of 15 panels each. It's time to figure out exactly how I will do this. I want to use only the existing wire connectors on the panels. Both strings will terminate at a combiner/breaker box that I want to mount over the deck area, in case I have to reset the breakers. After some playing around in Freehand, I came up with this configuration:

As I mount a row of panels, I must connect them because I will not have access to the wires once I put up the next row of panels. Now I can string the top panels together as shown.

November 28. The second and third rows of panels will require a special clamp on one or two corners of the panels. I will not be able to reach under the panels to attach all the upper bolts. After contemplating various clips, I've decided to make a stove bolt, post and plate clamp. I turned an aluminum tube to the height of the panels:

The tube goes over a 5/16" stainless stove bolt that is mounted on the rail with lock washer and nut (inside the tube, not shown):

I cut 1/4" plates from the short angles that I removed from the roof on September 19. They are already drilled with a 5/16" hole :-)

Here are two plates in place. I can securely tighten the plates because the aluminum tube prevents the plate from compressing the panel frames. I will wick some thread locker into the nut to be sure these will not loosen up.

November 29. Second row of panels mounted with bolts. I still have to add four plate clamps.

December 6. Snow and ice at 7 AM.

I connected the second row of panels with a copper grounding wire, as I did with the top row. Then I connected as many voltage wires together as I could. With the 12 panels on the right side of the roof all connected in series, I put a voltmeter across the two ends. 381 volts in the late afternoon sun. Open circuit voltage is about 33 volts per panel, so I should be getting slightly less than 400 volts from 12 panels. OK for late sun. There was some shade falling on these panels, too.

Looking west:

December 13. 26 panels up, 4 to go:

December 21, the day after about 20 inches of snow:

Nice to see the panels clean themselves off quickly.

December 27. All 30 panels installed:

January 1, 2010. Happy New Year.

According to inverter specs, electricity from the inverter to the house panel (240 volts AC, 25 amps) requires AWG 8 wire. I got 20 feet of 8-3 Romex: 3-conductor #8 wire and a bare copper ground wire in a PVC sheath. Here is the Romex going into the house through a 3/4" PVC conduit. The enclosure is an AC disconnect box, secured to the outside wall with stainless steel lag screws:

I mounted the aluminum combiner box on the roof by bolting it to a scrap of square tube aluminum that is bolted to the lowest rail. Four wires, two from each 15-panel array are combined in this waterproof box:

The inside of the combiner box looks like this:

January 4. I dry-fitted 1/2" PVC conduit from the combiner box to the lower part of the inverter, now mounted on the wall of the the house:

I also assembled a 3/4" conduit from the inverter to the AC disconnect.

January 9. I wired up the AC disconnect box. The hots (red and black) from the 8-3 Romex go to the knife switch. I let the neutral (white) pass through uncut. I attached the ground wire to the ground bar on the back of the box:

The 8-3 Romex continues on to the lower part of the inverter:

Inverter door open, the black and white wires from the combiner box go to + and - DC respectively. I have stripped the black hot wire from the 8-3 Romex cable. The white neutral wire is already connected:

The screw terminals for the AC connections are clearly labeled in the inverter:

Inside, I finished wiring up the sub panel:

January 10. I glued together the conduit pieces from the roof to the inverter. I put fuses in the combiner box and double checked the voltage and polarity of the solar panel connections.

One 15-panel series looks like this:

The other looks like this:

Not too bad, a difference of less than 1% between the two sets of panels.

I attached the top part of the inverter. I turned on the solar panel breaker on the sub panel, connected the AC disconnect, and turned on the inverter to test it (the agreement with the power company allows up to two hours of testing). Because of an oversight - not turning on the main panel breaker to the sub panel - I didn't get any power. When I figured this out it was 4:30 and the roof was more than half-shaded:

But the green light came on, showing about 230 watts of power... almost enough to make toast?

It's ready for electrical inspection, scheduled for January 13.

January 16. The electrical inspector had a couple issues with my solar installation.

1. The ground wires on the roof must be connected without using wire nuts.

2. The conduit on the roof must be supported.

To resolve these issues, I screwed the ground wires to a grounding bar in a weatherproof box.

I added aluminum angles to support the conduit:

With full sun on the panels, I tested the system. I turned the power on for a few minutes periodically during the morning. Here is a visual log of the power output:

For a winter day with hazy sun, I am happy with 5200 watts. The system should have no trouble delivering 6300 watts for many hours on a sunny spring day :-)

I observed my electric meter before I turned the solar power on:

I turned on the solar power. To my great surprise, my meter is already capable of running backwards :-D

As a symbolic test, I plugged my electric car in at about 2:30 PM:

The solar inverter showed over 3000 watts. My car charger draws about 1200 watts. The electric meter was still turning backwards showing that I was charging the car with only solar energy, just like in the little movie at the top of the page.

January 17. I'm putting on a new gutter:

I should soon be ready for final inspection.

January 21. Final inspection... passed!

I emailed a form to Atlantic City Electric showing passed electric inspection so they can approve my system. They replied that they have sent the application on to the Meter Department for final approval.

January 23. Gutter up, scaffold down, ladders back in the garage. I still have to hook up a data logging option to the inverter, to collect power data. This project is nearly done:

January 30. A representative from a local heating company performed an energy audit on the house today. This is a State requirement in order to receive the maximum rebate amount from New Jersey. Recommendations include some insulation in the basement and replacing the furnace and air conditioner with a heat pump. Might do that.

February 5. To request a State inspection, I snail-mailed paperwork to the NJ Renewable Energy Incentive Program (REIP) showing details of the completed project. The required documents are listed on this page under the heading, Request a State Inspection:


The package includes an as-built technical worksheet, pictures of the finished project, energy audit results, rebate form, a technical revision form, results from an energy calculation program and the true direction of the roof as provided by this website:


REIP will either inspect my system or waive the inspection. They pledge a response in one to two weeks.

February 10. I received an email from Atlantic City Electric saying my meter was switched out on February 4 and that an approval letter will go out "tomorrow or Friday." Sure enough, there is a new meter on my house (and a lot of snow...):

I like the "warning." Watch out: I generate my own power!

So the electric company took two weeks to come out and switch my meter. I take back all the things I was thinking about them. I didn't know they would switch my meter since my old meter was capable of running backwards. Thanks, AC Electric.

February 11. Atlantic City Electric emailed approval to turn on the solar panels. There is only one small problem, a gift from yesterday's blizzard:

I expect the panels to be clear by noon. Here is the house at 10:45 AM:

Power on at 12:30 PM and it ran all day, turning the meter back a few kilowatt hours in the process. I know why when we see the sun we say, "holy cow."

February 12. The first full day of solar power. Now I will start to get real data. How much power will I get from these panels? How long will it really take to get my money back? The inverter stores total energy output. This value is accessible from the menu on the front panel. I can compare this energy with my average energy consumption from 2008-2009 (65.5 kWh/day).

February 13. The first data are acceptable. I got 55 kWh after a day and a half of sun. I will periodically post data. Today is overcast but the panels are still putting out 1 to 2 kW of power. The bright white snow is reflecting light on to the roof.

February 19. I checked the electric meter as I left for work this morning: 874 kWh. I checked again when I got home after a mostly sunny day: 856 kWh. Nice.

What's left? I'm waiting for NJ to get back to me about a State inspection and registration in the Solar Renewable Energy Certificate (SREC) program. What is an SREC? According to NJ's energy website:

"Each time a (photovoltaic) system generates 1,000 kWh of electricity, an SREC is earned and placed in the customer's electronic account. SREC's can then be sold on the SREC tracking system, providing revenue for the first 15 years of the system's life.

Electricity suppliers, the primary purchasers of SREC's, are required to pay a Solar Alternative Compliance Payment (SACP) if they do not meet the requirements of New Jersey’s Solar RPS. One way they can meet their RPS is by purchasing SREC's. As SREC's are traded in a competitive market, the price may vary significantly. The actual price of an SREC during a trading period can and will fluctuate depending on supply and demand."

Currently, SREC's in New Jersey are going for about $550 per megawatt-hour of energy produced. At the current rate, my system should provide over $4000 per year. Is this real money or are these like "credits" from old sci-fi movies and TV shows??

March 9. The state inspector came on March 4. I received email confirmation yesterday that my system passed inspection! That's the last inspection. I'll send in the final paperwork and should receive my rebate within 60 days.

March 31. I received my electric bill for February 26 to March 26. This is the first "all solar" bill and it's as good as I could expect. Atlantic City Electric compares the bill to last year's bill during the same period:

Almost a 50% reduction in my bill.

May 1. I got my second electric bill: $155. That's half my old bill. Looking good.

I got my NJ Certification Number on April 28. This allowed me to register with GATS, the company that manages SREC's. More on that when there is more on that.

I don't expect my rebate for another 60 to 90 days...

June 28. I got my rebate check on June 23, about one year from when I applied for the rebate.

According to GATS I have officially generated 1.285 megawatt hours of solar energy, so I have generated one solar renewable energy credit. How do I sell it?

Selling SREC's.

August 20, 2010. In July, I tried to put an SREC up for auction at an SREC trading company. You tell them how much you want to sell your SREC for and they will put it up for auction for you. No fee charged for sellers. The going price had been $665 per credit for 3 or 4 months so that's what I asked for my solar credit. Unfortunately, the August price dropped to $664.99! so my credit didn't sell.

I got a tip from a solar panel enthusiast about a company that offers to buy NJ SREC's at a good price, so I emailed the company, njsrec.com. I told them I had three solar credits to sell and gave them the months they were generated. Solar credits produced before June 2010 are 2010 credits while credits generated after May 2010 are 2011 credits. Does that matter? Yes. 2010 credits are worth more. Credits will lose value every year. The company emailed back quickly offering me $674 each for my credits produced in April and May, and $643 for the June credit. These are the best prices I've seen for New Jersey solar credits so I accepted the bid. The company says a check will go out today.

August 23. I received a check for $1991. Real money!

Summary and Conclusions

Here is a financial summary of the project with approximate values:

Total cost of solar array $23,000
New back roof $1,000
Rebate $10,500
Savings on electric bill per year $1,500
SREC sale per year (conservative estimate including price drop) $3,000

My out-of-pocket price after rebate is $13,500. My savings per year from lower electric bill and SREC sale is $4,500. This estimate shows I will pay off the cost of the solar array in 3 years. Even if SREC sale collapses, the system will pay for itself after 9 years.

This a practical, economical, environmental project, a good investment. These results show why New Jersey is second only to California in solar power installations.

Update, April 17, 2011.

To date I have received $5200 by selling 8 SREC's generated during the first year of solar panel operation. I got a $3400 tax credit on my 2010 taxes. I have saved at least $1700 in my electric bill since the panels have been operating. That's over $10,000. At this rate, the solar panels will pay for themselves by August 2011, a year and a half after the panels started operating. That's a much quicker return than I imagined. Very nice.

This project convinced me to put solar panels on my garage, too.