The Cost of Solar Photovoltaics

One of the first questions I get about our solar photovoltaic system is about cost. While details vary by system size and details of the house, I thought it would be useful to share what it cost us. I mentioned before that we got the top-of-line panels from SunPower, so keep that in mind when examining these numbers. Also, as you’ll see, I don’t have the cost of individual components such as price per panel, or price for the inverter. These are the numbers that Renovus gave me in roughly the same format they gave me. At best this might give you a template for a very rough estimate.

Description and Quantity $/ea $
Solar modules SunPower E21 series, SPR-X21-345, 345W high-efficiency solar modules: 96 back-contact cells, white backsheet, 21.5% panel conversion efficiency, 19W per sq.ft. peak output, 25-year product and power warranty. SunPower Package-3 12
Inverters SunPower SPR-4200p-TL-1, 4200W, 208/240/277VAC inverter, dual Maximum Power Point trackers 1
Mounting systems UniRac SolarMount-I PV mounting system, 6005-T5 aluminum extrusion components, PE-certified, 10-year limited product warranty, 5-year limited finish warranty. Aluminum/stainless steel waterproof asphalt shingle roof flashings. 1
Monitoring SunPower Monitoring System for 1 SPR-xxxx inverter. Includes SunPower Data Loggers, SunPower Gateway, SunPower Wireless Display, Smart Monitoring Web Interface for homeowner and dealer, cabling, power supplies. 1
$1,198.88 $14,386.50
Electrical BOS Electrical balance-of-system for roof-mounted PV system – including as needed: wiring, metering equipment, conduits, safety disconnects, wiring enclosures, AC/DC load centers, electrical protection devices, safety signage, inverter accessories. 1
$2,473.50 $2,473.50
Materials Total $16,860

Labor is another $6,880 for a total of $23,740.

But then the rebates come into play. Renovus takes care of the NYSERDA rebate, which at the time this system was designed was $1.40 per watt. Our 4140 watt system (12 panels generating 345 watts each) therefore qualifies for $5,796 that gets cut off the cost listed above without me having to worry about it.

Then there are the New York State and federal tax credits. Both are based on the cost of the system after the NYSERDA rebate is deducted. That’s $23,740 – $5,796 = $17,944. The New York State tax credit which returns 25% of that number for a return of $4,486. The federal tax credit gives back 30%, for $5,383.

So in summary:

Cost of the system $23,740
NYSERDA Rebate ($1.40/watt) -$5,796
NYS Tax Credit (25% after rebate) -$4,486
Federal Tax Credit (30% after rebate) -$5,383
Our cost after filing taxes next year $8,075

When do we earn that cost back? It’s hard to say with lots of variables like the amount of electricity that we actually generate (which is dependent on things like how clear the skies are) and the cost of electricity in our area. Renovus estimates we’ll generate about 4800 kWh/year. If the cost of electricity stays at 15 cents per kWh forever, we’ll recoup the cost in a little over 11 years. Renovus’ projection takes into account historic rises in electricity rates so they estimate payback in under 9 years.

That’s all well and good, but it’s not all about recouping the cost of the system for us. We’re using less coal- and natural gas-produced electricity and we feel good about that.

By the way, in case you’re not familiar with how tax credits work, they’re not just cash given to you by the government. They’re credit towards tax that you owe. So a.) your tax liability has to be at least as much as the calculated credits for you to take full advantage (I think you can carry over excess credits to the next year, but I’m no expert on that) and b.) you don’t get that money until you file your taxes, which for us will be around April 2014.

With the monumental number of expenses we have from buying and fixing up a house, we don’t just have $9,869 (the total of the two tax credits) that we can afford to have tied up while we wait for next year. Many solar installers work with Enerbank (maybe other outfits too) to give their customers same-as-cash loans that remain interest-free for about a year, giving the customer time to get their tax savings and apply it towards the balance. It’s a great way to capitalize on solar savings early without locking up lots of cash.

One final, very quick note: solar leases are pretty popular. Their low or no cost to entry is attractive, but if you can afford to own your own solar system, I think you’re much better off keeping all the electricity savings for yourself.

Solar Install Day 4

July 1. I’m in Bedford, Massachusetts for work while my favorite house project is being completed back in Ithaca. Fortunately my wife was able to take a few photos.

Our system is built with SunPower X21 panels, the most efficient on the market. I’ve read a lot of advice online that the cost of these panels aren’t necessarily worth the added cost if you have plenty of roof space (in which case you’re better off getting the best cost per watt you can). For our roof, though, these are perfect.

Solar Install Day 4 1

Solar Install Day 4 2

Perfect Painters put up their sign the first day they started work, but Renovus didn’t get around to putting their sign up until the last day of installation. I don’t mind both of us showing off some awesome solar work.

Solar Install Day 4 3

I took this photo of the finished work on July 4. Gorgeous.

Solar Install Day 4 4

The monitoring system isn’t fully installed yet, so for the moment the only way to see how much power is being produced is via the inverter’s LCD. By the end of Independence Day we had generated about 20 kWh.

Solar Install Day 4

See also:
Solar Install Day 1
Solar Install Day 2
Solar Install Day 3

Snug Planet Energy Audit

On June 7 Mary Kate and Maria came from Snug Planet to hold a one hour education session with us. We took some action from that: we replaced that horribly wasteful showerhead with the 1.5 gpm Niagara Chrome Earth. My wife also had me replace a bunch of faucets around the house with lower flow aerators (I’m less pleased about this and I’m not convinced it’s that important anyway, given how little time we spend in front of sinks).

Three weeks after the education session Blake showed up to perform the full audit. Like Mary Kate and Maria, Blake asked us about our goals for the house. It’s important to clarify which of comfort, saving energy, or saving money is your highest priority, since payback on the cost of remediation can be both difficult to quantify and difficult to achieve. The work can be expensive and natural gas is cheap (and will likely remain so for quite a while).

We walked throughout the house, going top to bottom, so Blake could do a visual inspection. There are 3 closets (really access doors into the attic space) on the third floor that Blake said would benefit from having their floors torn up and filled with insulation. This would render these spaces unsuitable for storage, but would help seal off the living space from the attic. The floor cavity underneath the storage and living space needs to be separated so air doesn’t travel between the two spaces. The walls would also benefit from being filled with insulation. That drywall has bulged and needs to be replaced anyway.

On the second floor the main takeaway was that after the house is buttoned up, it will be more important to expel moisture from the bathroom. Blake recommended a bathroom fan in the wall.

I don’t remember much of note on the first floor other than Blake’s advice to turn the range hood fan on when using the oven. As the oven begins to warm you may get unburned gas and carbon monoxide that’s best vented outside.

Like the attic I expected there would be plenty of work in the basement, and it did not disappoint. Using a nifty gas sniffer Blake found two (!!!) minor gas leaks.

Gas detection

The device is pretty cool, but it’s hyper-sensitive so you still want to verify there’s a leak with the old fashioned bubble test (where you apply a soap or soap-like solution to a connection and look for bubbles), which did indeed confirm those leaks. Fortunately no leaks were found in the gas line leading to the dryer, which I hooked up myself.

When Snug Planet came for the education session Mary Kate suggested a vapor barrier to seal off the basement floor, but Blake believed pouring more concrete (into the rougher section of the floor) would be sufficient. He was more concerned with the walls of the basement, which he said would benefit from being insulated with rigid foam boards. He also approved of my draining the dehumidifier into the sump.

As my home inspector pointed out, the doorway leading to the basement access (often called “Bilco doors” although I don’t know if mine is actually Bilco brand) needs to be sealed off because it leaks pretty generously. Fortunately Snug Planet has experience in that sort of thing:

There were a few other minor notes about the basement, but then it was on to my most anticipated part of the audit: the blower door test. The blower door is an adjustable metal frame (to fit just about any size door) that holds some kind of nylon-like fabric that blocks off the door except for a hole where a powerful fan fits.

Setting up the blower door

The fan speed is computer-controlled in order to maintain pressure of 50 Pascals. Apparently this number is a building performance standard, and like many standards its origin was a bit arbitrary. Blake mentioned that while experts desired a higher pressure, the fans of the era when the standard was established (the 1970s maybe? I forget) were only powerful enough to maintain 50 Pascals, and that limitation defined the paradigm.

Keeping things at 50 pascals

Fixing the internal pressure allows us to measure the amount of air flowing through the home in cubic feet per minute. Blake said our number was about average for a house of this size and age. In the attic you could feel air rushing through the access doors, which isn’t surprising considering the living space is connected to attic space with a vents to the outside. Also unsurprisingly, there was lots of air coming in through the basement door too. Once you get past the obvious stuff, though, it’s helpful to use tools that give you better visibility into your home’s deficiencies.

That’s where this thermography camera from FLIR comes into play. I imagine this works better when it’s winter and there’s a more substantial differential between inside and outside temperatures, but even in summer you can notice obvious deficiencies. In this photo below you can very clearly see the outlines of the floor joists, suggesting there’s little to no insulation in the cavities between them.

Infrared camera

As with the gas detector, though, these gadgets still require you verify their results, and again a low tech solution was useful: Blake had a short piece of wire he stuck into available holes (I still have many outlet covers removed from when we painted) feeling for resistance that indicates some kind of insulation was present. Sometimes he could hook into the insulation and pull some out in order to identify whether it was fiberglass or cellulose.

Unsurprisingly, our walls are sorely lacking in insulation. Some of the rooms did have some fiberglass insulation that came from some previous owner’s renovation (plaster and lathe removed and drywall installed), but for the most part the walls are empty. This problem is usually solved by punching holes in the wall and blowing in insulation. Because our house is covered by two different materials, each level of the house would be handled differently. The upper level, covered in cedar shake shingles, could be entered from outside like most homes. Stucco, however, is very difficult to patch in an aesthetically pleasing way and Blake said they’ll usually blow in insulation from the inside in that situation.

At the end of the audit, Blake asked us how he could best help us proceed with our goals for the house. As someone with limited time and skills, I figured getting estimates for the various solutions we discussed throughout the audit would be helpful for deciding what our priorities should be. The attic easily had the most to gain, and Blake ballparked that the work to rip up the flooring and install insulation throughout could be in the $3000 range. Other things we’re interested in, as mentioned above, are installing a bathroom fan and insulating the basement with foam board.

There are a handful of easy things I can take care of myself, such as putting insulation around some of the pipes leading in and out of the water heater (why in, you ask? thermosiphoning can pull warm water into the cold intake pipe). The gas leaks are best handled by an HVAC specialist. For the rest we’re waiting on word from Snug Planet on how best to proceed and how much it might cost.

It was a great educational experience and well worth the four hours total (1 hour educational session, 3 hours for the actual audit). The cost in New York is free or really low, so there’s little reason not to get it done. I have no basis for comparison, having only gotten one energy audit done ever, but Snug Planet was as friendly, helpful and knowledgeable as their reputation indicated. I’m looking forward to seeing what else they can help us with.

Color Selection

I have a bunch of posts about the solar installation, energy audit and progress on the exterior paint job on the way, but they’re all on the back burner. I was in Massachusetts this past week for work, we hosted guests from out of town over the long weekend, and now we’ve been scrambling to choose colors before Perfect Painters gets started on actual painting (as you’ll see in a future post, they’ve been busy scraping, sanding, priming and replacing shingles).

We’re considering a number of options, with an obvious tilt towards green:

Paint Options 1

The front-runner is Sheraton Sage on the shingles, Garden Gate on the stucco, Roycroft Vellum for the trim, and Roycroft Copper Red for accents like window sash. The last two colors come from Sherwin-Williams’ Arts & Crafts collection.

Paint Options 2

As a reminder, here’s how the house was painted when we took possession. We’re not fans of brown or yellow.

Front of House

You can see we’re also considering Roycroft Bronze Green for the stucco. Using a lighter combination might be on the table too, such as Colonial Revival Green Stone on top and Sheraton Sage on the bottom.

That last option would be a lot less Craftsman-appropriate than our leading choice, which is already pushing it with that sage, but we’ve already decided that while we want to respect history as much as possible, we don’t want to be shackled to it either. We’re thinking that combining historic and modern colors and using even the classic colors in novel ways (Craftsman houses didn’t really feature very light trim like the Roycroft Vellum until the late 1910s or early 1920s, as far as I can tell) is the best way to honor the past and consider our tastes too. Besides, it’s not like anyone else in Ithaca is choosing from the historic palette.

Historic Ithaca‘s library (you get free access if you’re a member) was immensely helpful in getting us started. Robert Schweitzer’s Bungalow Colors (affiliate link) is an outstanding resource too. It’s the only book dedicated to choosing colors for Arts & Crafts house exteriors and contains history of the Arts & Crafts movement, color theory, color choices for certain house types, before & after examples, and paint swatches from Sherwin-Williams. It’s been incredibly useful and has helped support some of our decisions such as the red accents and two-tone body.

The pressure to get this right is intense. Unless we want to spend thousands of dollars doing this again, the decision could last decades.