That’s right: zero. It works two ways. The panels can be leased or, less well known, obtained through a power purchasing agreement (PPA); and, like so much of what it takes to build a zero energy home, the choices are going mainsteam. The number of third-party residential and commercial installations more than doubled in the last two years to over 213,000, according to Greentech Media, a research firm, and reported in The New York Times Thursday.

A solar panel leasing deal getting done

Not having to pay for them is just one advantage over buying. The home owner can also count on getting predictable utility bills. They also don’t have to worry about maintenance, repairs or replacements of the panels during the life of the lease or PPA, which generally run from one to two decades.

Not that there isn’t a down side. The negotiations can be more complex than just buying panels and the transaction costs are likely to be higher too. For many home buyers though the advantages outweight the disadvanages and either choice just may be the best solar deal – if they can get it.

As accepted as they are becoming, the third-arty solar deals are still only widely available in some states. They’re states where there are financial incentives in place that make it worthwhile for companies to set up a business. These include most states in the northeast and the westcoast.

For example, California, by far the biggest solar market, is also the biggest market for solar leasing and PPA. Indeed, buying solar panels only account for about a third of the solar market in the golden state.

A few companies are consider the leaders, like Sunrun, Sungevity and SolarCity. The last is considering an initial public offering, so that’s a good sign that the business is going to be around awhile. There are also local independent companies that work on their own or through big box home supply retailers, like Home Depot and Lowe’s.

In my book I thought the newness of the business was the biggest concern. Now, that the business appears to thriving there is good reason to hope that the zero energy’s biggest expense just may be well within homeowners’ reach for years to come.

Pulleyup is just south of Seattle where in and out of the city is home to three of the more interesting zero energy efforts in the country. I’ve already written about two of them. One is due west of Seattle, across Puget Sound on Bainbridge Island, while the other is east of town, in suburban Issaquah. Now comes a third – right in Seattle.

"Zero energy" home in Seattle

The Bainbridge home stood out for several reasons. It was one of the earlier zero energy bids, having been built in 2008 – when the real estate market was imploding. It was also the first LEED certified home on the island and was built on spec for a middleclass market at a time when most custom zero energy jobs were distinctly upscale.

The new Issaquah effort, just noted here last month, is a townhouse development that was built LEED platinum and was honored by the Department of Energy as Water Sense qualified.

I’ve actually already noted what’s special about the Seattle house. It’s in town, an infill, amidst rows of homes. You’re not going to find many of those anywhere.

It’s got another sustainable feature not seen nearly enough in zero energy bids. The ground floor of the 3-bedroom 1,800 square foot SIP-constructed house is stained concrete. Not only is it cheap or cheaper than most flooring materials, but it absorbs heat and keeps the house warm in cold weather.

The homeowners who are also the house’s builder, bought the land at 612 NW 60th Street for $180,000; spent $208,000 on materials, labor and 6-kilowatt solar panel installation; paid $16,582 in sales tax; and $12,500 for permits for a subtotal of $417,082.

They hope the house will serve as an inspiration for others to build a home like there’s. First, let’s see if it is zero energy come the same time next year.

ZHome, as the 10-house townhome community is known, is about 20 miles east of Seattle in Issaquah and is loaded with energy and water efficiency features.

The zHomes in Washington

Since it’s new I have to add the caveat that the homes still have to prove their worth. They’ll need a year to show they can produce all the energy they use and that they’ll use much less water. Who knows, maybe their occupants will take longer showers and waste the savings their Water Sense features bring.

Still, any future behavior shouldn’t detract from what the builders put in the homes. Many of the features you’d expect from a zero energy home are inside the townhouses.

Insulation is one of the houses strongest features. The houses have R-60 in the ceiling and R-38 in the wall. The walls alone have 9 inches of expanded polystyrene in the 2 x 6 framing and on the outside of the framing. The townhouses also include double pane windows at U-.33, geothermal heat pumps, heat recovery ventilators, hydronic heating, CFL and LED lighting, Energy Star appliances, solar panels totalling 72 kilowatts and tight construction.

The water saving features are on target too. Landscaping includes drought-tolerant plants that won’t require any water. The dual-flush toilets are 31 percent more efficient than standard toilets and use gray water collected in 1,000 to 1,800 gallon cisterns on site. Shower heads flow at a meager 1.4 gallons per minute versus 2.5 GPM. High efficiency clothes washers use about 55 percent less water and dishwashers use 73 percent less than typical appliances. The clothes washers also run on recycled rainwater.

The homes are also big on sustainability. They use recycled and local building materials. The wood is FSC certified and little vinyl and other nonsustainable materials are used.

The development is located next to a park and ride and, while it has parking for cars, the spots are microcar size.

Impressive, but then there’s the cost. The one-, two- and three-bedroom units are 800 to 1,700 square feet each and are priced from $385,000 to $625,000. As one blogger note, that’s a lot of money for a suburban townhouse.