Monday, September 16, 2009, 2:00 PM: PNM has just completed the final testing and my solar electric system is now turned on (Clouds form, rain falls). It's been quite a while since writing Part 1 so you may want to reread it for the backstory. This is a narrative and technical, detailing what's happened since last October and also the insights gained. Let's get started.

First, you might be wondering "Why did it take 10 months?" to which I say: While patience is a virtue, with PV systems it's a necessity. Due to expiring Federal incentives, everybody was doing solar installs in late 2008, causing multi-month backorders for parts, particularly rack hardware. While waiting, our windows started to leak and a few other home issues took precedence which meant canceling the project until Spring. When Spring rolled around, the microinverters I was going to use had been end-of-lifed with new models on the way in a couple months. When the new models came out, they were backordered for a couple more months. Which brings us to late August, when everything became available all at the same time. Whew.

Four very positive cost-related changes have taken place since that everybody who wants to do this should know about:

1. The Federal tax credit for PV systems was extended and uncapped. The Fed will now pay a 30% tax credit for all parts and labor on a PV system. There is no longer a $2000 limit for residential applicants. That means if you buy a $10,000 system, you get a $3,000 Federal tax rebate on it.

2. Not to be outdone, the state has enlarged its 30% rebate to 40% (Minus whatever % the Fed picks up). This means if you buy a $10,000 system, get a $3,000 Federal refund, you also get a $1,000 State tax rebate. Thus, 40% of the install cost is given back the first tax season to follow installation.

3. PNM's REC program now extends to 2021 instead of 2018. That's even more years of getting a $0.13 per KW/h credit, even if you use that KW/h.

4. PV Panel prices have dropped remarkably. The competitively priced panels I planned on buying in 2008 were $4.60/W. The panels I bought this year were $2.99/W, a 35% drop.

I restarted the project in early summer, getting in touch with PNM to find out how to reapply. The members of PNM's Photovoltaic Program, Jody Karp, Anthony Bueno, and Frank Andazola, were all exceptionally helpful and friendly. I needed to fill out slightly new paperwork but there was no new application fee. While the heads of PNM might be up to no good, the people actually in charge of the PV program are all enthusiasm and positive. Small groups have big hearts.

It took a few weeks to decide on the new system components, get the paperwork done (heavy procrastination on my part), update the schematics and send in the plan. The new contract in just a few pages thick, instead of last year's paperwork that was the size of the small city's phone book. Approval came quickly at which point I changed my mind on some parts and submitted it again. My god they're patient. Anyway.

The final plan was to get 5 CSI CS6P-200 panels, 5 Enphase M190 Microinverters and some Unirac Rapidrac G10 ballast mount rack hardware. DRB Electric did the AC-branch wiring for me. A friend, a neighbor, and I did all the roof work.

A few thoughts on doing this for least amount of money possible:

1. The most expensive part of any solar installation remains the panels themselves. A friend and I bought and split a pallet of panels which drove the cost down. Affordable Solar, a local business who sells across the world, even split the invoice for us (which will come in handy during tax season).

2. Rack hardware was the second most expensive item, $300 per panel. (The next row I install will only be $200/panel due to one less ballast tray being needed) The rapidrac is very easy to install, but also expensive: Rack hardware costs half as much if you're willing to put holes in your roof. Further, you could make your own racks for even less. I've seen local carport pictures where the rack system was made of wood.

3. Whether you do the wiring or somebody else does, you need a permit from the city. If you, the homeowner, want to pull the permit (and you aren't an electrician), you have to pass a 25 question open-book test. DRB provided the permit, installed the meter base, cutoff switch, conduit, outdoor junction box, wired it up, and came back when there were problems for about $400 of labor (total cost was higher since they provided materials, but I'm factoring those out since they were necessary regardless). This seems like a bargain to me, but if you want to do it yourself it'll cost less and you'll learn more.

After PNM approves your plan, you go out and do the installation, then there are 3 inspections.

The first is the city inspector. He looks at the wiring from end to end, making sure it conforms to the NEC, city guidelines, etc. Make sure to be there when he shows up or he won't inspect anything and the city will charge you $40 to have him come back. He's thorough, looking at everything on the ground and on the roof. Upon first inspection, he took all of 60 seconds to reject the work. Immediate problems were the wrong gauge wire being used for the circuit (Must be #8 THHN or larger to the AC cutoff). The cutoff needs to be fused. Here's a picture of what was done after the first inspection (Sorry, no before shot):

The box on the left is the meter base, the box on the right is the AC cutoff. The pipe that runs to the left of the meter base goes to a 240V circuit breaker in the main panel. The pipe that runs above the AC cutoff goes to the solar panels on the roof. Second inspection fails: The neutral (white wire) can not be bonded to the ground (green wire) in the meter base on PV systems. It's normal to do it otherwise, but for PV systems this is a no-no.

On the third visit, the City Inspector (Richard Luna, easy to work with even if he's dinged the setup twice) passes the system and puts a green sticker on the side of the meter base. At this point the city notifies PNM that the system has passed and it's time to put a meter on the box. This can take up to 2 weeks. I let 2 weeks pass and nothing happens: Dial up PNM and find out they never got the notice of inspection completion. Evidently this happens quite frequently, but usually people don't want 2 weeks to find out. A quick call to the city electric later (505-924-3311) and PNM has the information they need in 3 minutes. Lesson learned: When you're going to have to wait many days before you come to the top of the queue, call and make sure you're in the queue before you start waiting.

For the next inspection, the meter guys come out and verify the AC wiring on the side of the house. Wouldn't you know it? More problems with the meter box: The hots from the circuit breaker need to be on the bottom, the hots from the PV system need to be on the top. Last week they installed a meter on a system setup like mine and the meter literally exploded. DRB came out for the third time and fixed the problem (This was their first PV system, so we were learning together. The mark of true professionalism is the response in the face of trouble: DRB showed up the same day or the next day for every problem that came up and fixed it without fail). This is what the meter base looks like when correctly wired:

The funny thing is that PNM has the schematic for the meter base diagram online. Once upon a time, I knew this, but completely forgot. Getting this right would have shaved weeks off my install time. So, if you're going to do one of these systems, remember the diagram on PNM's technical requirements page. Infact, just get cozy with that technical requirement page.

The following morning, the meter guys come back out, verify all is well, install the meter and lock the disconnect. I call Anthony Bueno, the man with the key, and tell him the good news. He's free that afternoon! Oh yeah! The final test PNM performs is to make sure that when the power goes out (IE, a blackout), the system turns itself off. This is called "anti-islanding." This is an important behavior because PNM linemen assume that when the power goes out, there will only electricity entering the system from one side of the break. With residences having "islands" of power generation, this might not be true, and this can result in the lineman being electrocuted. Anthony hooks up a really cool voltmeter that displays the sine-wave of both PNM's output and my PV output, then toggles all the disconnects and verifies my system turns itself off. He takes the lock, shakes my hand, and we're done.

This is what the final setup looks like on the ground. The green tag on the REC meter prevents the meter from being opened (IE, tampered with). PNM provides the red placard on the AC disconnect. The two giant labels, a PNM requirement, were $10.00 courtesy of A&A Signs on Zuni. You might notice the metal wire hanging from the conduit to the left of the REC Meter.

This 12" length of PVC has caps on both ends and hangs from the conduit. Inside is a copy of the line diagram and site map from the application process, required to be available at all times in case of emergency. These pages must be laminated. I'd never had anything laminated before, but it turns out they'll do it at Kinkos for $2/page. Yes, my handwriting is that bad. That's it for everything down below- let's get to the roof.

The grey box on the left is the end point where DRB stopped and I started. The elevated conduit goes over the parapet and straight down to the AC cutoff, already pictured (The other conduit goes to the swamp cooler). Inside the box, the #10 wires from the AC cutoff below are connected with wire nuts to the 2 hots and 1 neutral that run inside that black cable. That's #6 copper serving as ground- it didn't need to be that big, but it's what Lowes had in stock that day. Speaking of which, Lowes has no capacity to handle tax-free sales on solar installations, so even if you're armed with the Tax Exemption Form they'll still charge you sales tax. Nobody else had any trouble accepting it, so if you do this yourself, save a few bucks and shop somewhere other than Lowes. I bought about $100 worth of various bits and pieces from them, so the total taxes paid on this project were about $6.

Lots of interesting stuff in this picture. The silver metal box hanging out under the panel is the microinverter. There is one of these for each panel. They are tied together in series, ending in the previously pictured junction box. The two wires that run from each panel to each microinverter are the only DC wires involved in the entire project (this cuts out a lot of the complexity of traditional high-voltage DC PV systems). All wires are zip-tied to keep them off the ground. The copper ground wire runs from each panel to each inverter. Also pictured, the rapidrac ballast mount system: 4 parts per panel, manufactured right here in Albuquerque, down on Broadway. Two legs screw directly to each panel, and then a ballast tray on either side is connected to the legs. 26 pound 16"x8"x4" blocks hold the system down against gusty winds. When I got the system I didn't know how many blocks to get so I called Unirac and they said "Just put a few up for now and we'll run the calculations for you". I bought 32 and put them in place. Have you ever pulled 832 pounds of material up 15'? It's strenuous. Two days later Unirac's engineering analysis said "You need 24." Argh! Lesson learned: If you go with a ballast mount system, have the company run the engineering analysis for you *before* doing the install.

It's hard to take a good shot of the panels since they're on the south side of the roof, but here they are in all their glory. Coincidentally, we scraped the pebbles off the roof before laying down the ballast trays. It's important to do this since ballast over thousands of tiny marble-shaped rocks does not stay put. That beige box on the right is a mastercool. If you ever need to replace your rust-bucket, it's the way to go.

And now, for some numbers. First, power production. There's 5 panels each rated for 200W, that's 1KW. The DC/AC conversion has some inefficiencies, so there's a 5% loss with the enphase inverters. That means, under optimal conditions (Panels at 75 Fahrenheit, sun directly perpendicular to the panels, no clouds or dust) each inverter will receive 200W DC and output 190W AC, resulting in 950W of production every hour. This does not usually happen. The rule of thumb in the industry is that you get 80% of the rated power, but I'm seeing peak power well above 800W. In-fact, before a cloud rolled in there was a glorious moment where the monitoring device announced 900W of production on a hot sunny day late in the morning. After 2.2 partly cloudy, somewhat rainy days, my REC meter says 11KW/h have been produced.

Second up, money: With PNM, PV panels pay for themselves in 2 ways. The first is that they produce electricity that I would normally pay for. On average I pay $0.09 per KW/h, so for every KW/h produced and consumed I've saved $0.09. The second is that for every KW/h produced, PNM's REC program pays $0.13 (Even if I use that generated electricity). Thus, every KW/h is worth $0.21. In Albuquerque we average 6 sunny hours a day across the year, so that's $0.21 * 365 * 6, or $460/year in electric bill savings. Let's call it $400 to allow some of the conversion inefficiencies in.

Finally, lets talk overall cost. Essentially there are two cost factors: 1-time startup costs, and per-unit-of-production costs. Startup cost (Including an optional $350 monitoring device): $1,549.50. Per-unit-of-production costs: $6,005.61. Grand total before state and federal incentives: $7,555.11. After incentives, $4,533.06 or $4.53/W, which means the total payback time is 11.3 years, assuming PNM's rates don't go up (Which they're going to... again!). The system can be expanded to up to 15 panels before additional wiring is required and, due to there already being an ballast tray on one side, adding additional panels will be only $625.20 after incentives (That's $3.13/W). Between generation and REC payments, going to 2KW should nearly cover my electric bill and reduce the payoff period to about 9.5 years.

If all this sounds like a good idea, an intriguing idea, or otherwise you want to know more, I strongly suggest making it to this year's Solar Fiesta at Highland Highschool Sept 26 & 27. Last year I went and was offered wholesale price on DPW rack hardware, so if you think you want to get involved, it's worth the price of admission.

And finally, everybody's favorite part, the meter spinning backward.

Up sometime in the future, Part 3 will followup with some actual production values so you know what to expect around here, details of registering solar rights (No second story for you Mr Neighbor!), and anything else that comes up between now and then. Hope you enjoyed it.

Views: 4322

Comment by Barelas Babe on September 16, 2009 at 10:59pm
OMG - this is such an awesome post!
Comment by Masshole in Fringecrest on September 17, 2009 at 12:05am
Revolutionary Resource.
Comment by slamwagon on September 17, 2009 at 8:13am
Comment by RivetGang on September 17, 2009 at 8:42am
Great information... your 2 posts on this make me seriously consider this option!
Comment by abqmom on September 17, 2009 at 9:42am
totally awesome! you should hire yourself out as a solar contractor!
Comment by hettie on September 17, 2009 at 10:20am
tons of easily understood info and pics--these have been really great posts! thanks brendan!
Comment by cathyray on September 17, 2009 at 10:21am
Comment by shotsie on September 17, 2009 at 10:52am
Your posting is very informative and should be passed around so that others could see how much work goes into installing PV panels. Maybe you could work with PNM to set up a demonstration for prospective PV buyers.

I'm surprised that PNM isn't training electrical contractors on how to set up the connections correctly (once again, your posting would be really helpful, since it shows about every variation of wiring possible.) They probably need a list of qualified contractors, so you don't have to re-do wiring once, twice, three times.... - it's a waste of your time and money.

I had a hard time visualizing the ballasted mounting system, so thanks for the photos. But I do have a slight quibble with the payback - since there's no storage, you can only use the power you produce during the daytime - so, if it's summer, you'll have a cooler going and probably use the power, but during the spring/fall maybe winter, your house will probably not be using 1 kW, so the payback changes from 0.22 to 0.13 for the difference between actual use and 1 kW. Unless you get a plug in hybrid that you can charge during the daytime, that is.....
Comment by Brendan on September 17, 2009 at 11:11am
Thanks for all the positive feedback!

There are already some great solar contractors out there. The Nm Solar Energy Associationhas a great list of providers. I asked 310 Solar who they used to do the wiring and they said they use Prestiage Electric for all their work. Prestige seemed to have more work than time when I contacted them, so it fell back to DRB who's done most of my previous wiring jobs.

Regarding payback quibles and storage, the grid effectively is the storage. If by some miracle of conservation we happen to use less electricity than we produce in a month, PNM credits the KW/h and applies it to the next month's bill. In the unlikely event that a year goes by and the power meter is still in the black, PNM will cut a check for the wholesale rate which is about $0.05 per KW/h. Worst case scenario, the value drops from 13+9 to 13+5. With a system as small as mine, this is unlikely to happen (especially since we have 4KW/h per month!). Naturally, if it *did* happen, I wouldn't mind having the fiscal impetus to pick up an electric car....
Comment by Masshole in Fringecrest on September 17, 2009 at 11:48am
Brendan, this may seem like a dumb question, but is there any actual roof penetration? It looks like the racking (with the concrete paver looking ballast thingies) just rests on the roof- is that the case?

I have a PE membrane roof and don't want to penetrate it anywhere, should I choose to do this.


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