Mountain Solar: Page 4 of 4

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Inside this Article

The home and its PV array.
The 2,148-square-foot floor plan includes three bedrooms and two bathrooms on the main level. The home’s semidetached garage can be accessed via a workshop space off the laundry and mudroom.
The Palmers relax on their deck.
In the coal-heavy state of West Virginia, solar shines at Rita Hennessy and Sean Palmer’s new custom-built home in Shepherdstown.
Windows in the dining area.
Large windows on the home’s south face provide ample daylighting to interior spaces. They also admit solar gain in the winter, reducing the home’s need for supplemental heating.
Clerestory windows let hot air escape.
Clerestory windows, which are opened and closed by remote control, aid in cooling the house by venting any accumulated hot air.
Thick, insulated walls and double-pane windows slow heat transfer, keeping the house cool in the summer and warm in the winter. The 4-inch-thick concrete floor acts as a thermal battery, storing and releasing passive solar heat gain.
Masonry heater has an oven.
Rita pulls a pizza from the Empire masonry heater, which serves as a backup source for space heating.
Minisplit heat pump, interior component.
Sean checks out the minisplit multizone heat pump, which provides auxiliary cooling during the hottest part of summer.
The outside heat pump component.
Sean and Rita’s dog guards the air-source heat pump’s outdoor unit.
Charging the electric car.
In addition to powering their home, Rita and Sean’s PV system also provides the power for an electric car-charging station. Here, Sean plugs in a friend’s EV.
Rita in her energy-efficient kitchen.
Rita stands in the kitchen, which features a Thermador steam oven and other Energy Star appliances.
The home and its PV array.
The Palmers relax on their deck.
Windows in the dining area.
Clerestory windows let hot air escape.
Masonry heater has an oven.
Minisplit heat pump, interior component.
The outside heat pump component.
Charging the electric car.
Rita in her energy-efficient kitchen.

Beyond Passive

Hennessy and Palmer were determined to offset any electricity their home used with a batteryless grid-tied PV system. They turned to Mountain View Solar (MTVSolar) in nearby Berkeley Springs, West Virginia.

“With a new home, there’s always some guesswork involved in adequately sizing a PV system,” says Pablo del’Aguila, the crew lead/field engineer at MTVSolar. “We used the electricity bill from their old house and then made adjustments based on the new home’s specs. Based on the size of the house and the loads of the more efficient appliances, we came up with a conservative estimate.”

The guesswork paid off. The couple records daily system production data from the Enlighten website. Since its installation in July 2012, the system has produced more electricity than the home has used. Since November 2012, when the couple moved in, the 6.3 kW system has generated an average of 700 kWh per month, while the home consumed an average of 563 kWh per month. Thanks to the excess generation, the couple has never paid an electricity bill for the home. The microinverter-based system allows for module-level monitoring, making any future troubleshooting easier. An additional tie-in point was also added to accommodate system expansion.

With the exception of a propane cooktop and the wood-burning masonry heater, the home features all-electric appliances, including one of Hennessy’s favorite items—a Thermador steam and convection oven, which cooks food more efficiently with steam and reduces baking and roasting time compared to a conventional oven. “We cooked a 14-pound stuffed turkey about half the time (in 2.5 hours), and it was golden-brown and fabulously moist inside,” Hennessy says.

The PV system’s gross cost was $34,860, or $5.50 per watt. After rebates and incentives, the net cost was $14,402—$2.28 per watt. The couple benefited from a $10,458 federal tax credit and $4,000 state tax incentive (including a state tax credit for the 240-volt car charging station in the garage). The couple currently owns a Prius but does plan to buy a plug-in vehicle in the near future. “The state tax credit for the charging station was so good we couldn’t pass it up. It just seemed easier to install one during construction while the walls were opened up rather than to add it later,” Hennessy says. “We planned for the future.”

Comments (16)

DaisyAdk's picture

Thank you Michael Welch. This price is closer to what I've found. Where did you come up with this info? I'd like to track it down further even if it does cost more.

Michael Welch's picture

It was sent to us as a correction by the manufacturer, after they saw the misprint in the article.

DaisyAdk's picture

Thanks again. Can you provide the link or contact information you have...I'm getting a website but I wonder if you have anything more direct.

Michael Welch's picture

I web searched Empire Masonry and found their web site, which has this content:
EMPIRE MASONRY CORP.
231 Norfolk Street Walpole, MA 02081
508-660-1011

DaisyAdk's picture

The Phoenix kit from Empire Masonry sounds exactly right for my place in the Adirondacks. I wonder where you were able to purchase this kit at "roughly $1300" ? This is not the price currently listed anywhere I can find it. I do have a mason to assemble the core.

Michael Welch's picture

We do not know the source of this error, but this kit costs $3,900 and an additional $900 for the bake oven, according to the manufacturer. We have corrected the online version here.

Rise2012's picture

There was a mix up in the interpretation of the state tax laws. Originally we were expecting to take full advantage of the tie in of the car charging station and the large solar array that would have credited us with $10,000, but as the laws were not finalized at that time, we only qualified for $4,000. That is where the other $6K went to. The charging station installed and inspected probably added $2K to the cost. You can find cheaper ones at your local stores then add in the electrician and permit if necessary.

DM Lewis's picture

Thanks for the quick, and thorough response. I am sure you are heart broken over the lost $6k. I was hoping the charging station credit was $6k but only cost $2k -- then everyone would add one to their project. :-)
You still ended up with a very nice place. Enjoy.

DM Lewis's picture

At the end of the article, the PV system was listed as costing $34,860, with $10,458 federal credit and $4,000 state incentive. Where was the other $6,000 credit/incentive to come up with a net of $10,458? Was this the car charging station? Unfortunately, I cannot find any incentive in Virginia. How much do you think the charging station added to the cost? Thanks.

Debra Coleman's picture

Marc and Micheal, both of your comments on the slight easterly orientation of the plan/south wall are valid in that often it can be good practice in any location that has hot summers, but it does depend upon the particulars of the micro-climate, views, topography, etc. In even warmer climates I often recommend even further orientation that 10 degrees since the south wall can be in shade much sooner on summer afternoons. With one of my favorite design tools, the effect of plan orientation can be visualized and you can enter data on the other factors that affect overhang length: http://susdesign.com/overhang_annua...
Debbie Coleman, Sun Plans (Architect of the RISE house)

Marc Fontana's picture

The architect recommended that the house be oriented 10 degrees east of south to minimize afternoon heat gain in this West Virginia climate. That sounds like good advice to me. Wouldn't this practice be a good idea anywhere in the northern hemisphere?
What kind of water heater was selected ? With surplus PV energy, an electric heat pump heater would make sense.

Rise2012's picture

Hi Marc, Yes, an electric hybrid, heat pump, GE Geospring hot water heater.

Rise2012's picture

Hi Marc,

With my limited expertise in solar home construction, I could comment about the 10 degree east of south orientation. It would depend on the amount of southern glazing %, how much thermal mass the home may have, and how tight the envelope. A passive solar home with much less glazing may want to take full advantage of direct 180 degree orientation and summer heat gain would not be so much of an issue.

In regards to the hot water heater, we have two. The primary is a GE Geospring hybrid (heat pump/conventional) and a point of use Rheem under the kitchen sink. The POU eliminates the long run from the main heater and waste of water just to get warm at the faucet or dish washer. With the excess energy that we're producing I have found that it makes sense to run the primary unit in heat pump mode during the summer and gain some dehumidification and cooling of the air then switch to conventional during the winter months. It is harder to extract heat energy from cooler air and who needs to make the air cooler inside the house in the winter.

Regards,
Sean Palmer, the "SE" of RISE.

Michael Welch's picture

The benefit of offsetting from south a few degrees would also depend upon geography (are there mountains or buildings nearby), landscape (a forest to block sunlight on one side), and microclimate (is the area foggy for part of the day).

Rise2012's picture

RISE Builder - Thomas Sandretzky, TS Construction, Shenandoah Junction, WV

Debra Coleman's picture

It's unfortunate that the article didn't talk a bit more about Tommy's role in construction, but I know space is limited. Tommy did a very good job of paying attention to detail and listening to the client. Clients often tell me that they cannot find a builder with passive solar experience in their area, and my response is that since the passive solar components are typically nothing unusual, then look for a builder willing to listen and follow good building and energy principals in general.
Debbie Coleman, Sun Plans

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