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Affordable Solar House Plans

These modern town houses in northern Oregon are shining examples of building with energy use in mind.

Innovative financing for this Mosier, Oregon, town house development allows investors and homeowners alike to share in the incentives and financial benefits of harnessing solar energy.

Would home buyers pay a premium to have renewable energy integrated into their new town homes? Peter Erickson, owner of Urban Fund Inc., a Pacific Northwest development company, was pretty sure of it. "The public is very aware of and concerned about the rising costs of utilities. If a prospective buyer can purchase a home that consumes less energy than a typical home and produce a portion of its own energy," says Erickson, "then it's not a tough business decision."

So he worked with his architects and a solar consulting firm to integrate photovoltaic and solar hot water systems into his 34-unit development in Mosier, Oregon. After some preliminary number-crunching, he wasn't confident that homeowners would be willing to front the large $28,000 per unit initial expense that the two RE systems would require. But some savvy financial planning saved the day, allowing Erickson to realize his plans to add a strong renewable energy component to high-performance housing.

Making RE a Reality

Erickson tapped into the talents of solar consultant Doug Boleyn of Cascade Solar Consulting, to figure out an attractive financial strategy for incorporating renewables into the development.

In Oregon, financial support for both residential and commercial solar systems is strong. The state offers generous tax credits for both home and business owners of qualifying grid-tied systems, and the nonprofit Energy Trust of Oregon offers additional cash incentives. Adding in federal tax credits for residential and commercial solar energy made the decision to install renewable systems a sound financial move.

"The utilities no longer have a monopoly on supplying power. Mosier Creek Solar is doing it, and at lower electric rates."

—Doug Boleyn, Cascade Solar Consulting

Boleyn compared private and commercial solar incentives and laid out two possible scenarios, based on a goal of producing about half of the development's electricity and hot water with solar energy.

One approach was to leverage federal incentives available to private individuals for residential solar installations. Each homeowner would qualify for a maximum $6,000 Oregon state PV tax credit, plus a one-time $2,000 federal solar tax credit. Although this would take care of a chunk of the upfront cost, the combined credits represented less than 30% of the total capital cost of the solar equipment on each home. Plus, Mosier is a vacation destination, with Washington State right across the river. Washington residents who purchased a town house as their second home wouldn't be able to use Oregon's tax credits.

The second option was to arrange for the solar equipment to be commercially owned by a subsidiary of the development company. Business owners of solar installations qualify for much higher incentives than do individuals under both the state and federal programs. With no caps, the state and federal business tax credits have potentially higher value, and businesses can also depreciate the solar equipment, a tax write-off not available to individuals.

In addition to the tax breaks, the Energy Trust of Oregon offers incentives to property developers who install solar-

Todd Lefever

Richard Mailman (2)

affordable solar

By clustering the 34 residences into eight buildings, Mosier Creek Place devotes half of its 5-acre site to maintaining the existing creek and grasslands.

Large windows admit an abundance of natural light into each townhome's interior, reducing the need for artificial lighting.

Richard Mailman (2)

electric and solar thermal systems on buildings. The result: The combined business incentives would be enough to offset 70% of the systems' installed costs, a savings Erickson couldn't pass up—and would be able to pass on to the homeowners.

To capitalize on the largest incentives, Erickson formed a subsidiary, Mosier Creek (MC) Solar LLC, to own and operate the systems for a minimum of five years. This third-party investment group bought the solar equipment and took all the utility and tax credit incentives. In addition, they took accelerated depreciation for the improvements over a five-year period.

In effect, MC Solar became its own solar utility, selling the solar electricity generated by the rooftop systems to the homeowners at about 15% less than the local utility's retail rate, a significant savings. Each homeowner has a netmetering agreement with the primary utility (Pacific Power) and can offset with solar up to 100% of their electricity use at the same rate that the utility charges.

The addition of Btu meters would have made it possible to meter the energy produced by the solar water collectors as well, but the investors were satisfied with their return on investment without having to claim the water heating savings. So the

Todd LefeverTodd Lefever

approximately 2,500 kilowatt-hours equivalent annual energy from the solar water heating system on each town house is provided to the homeowner at no additional cost.

At the end of five years, homeowners who wish to purchase their rooftop solar systems will be able to buy them at a fraction of their initial cost from MC Solar. Owning the systems will mean that homeowners get low-cost solar energy from their systems, helped by renewable energy credits (green tags) and other available incentives.

A Model of Success

Erickson and his team, including Cascade Solar, Surround Architecture in Portland, and local green building certification agency Earth Advantage, have broken new ground for renewable energy with Mosier Creek Homes. "This is a first-off model for this sort of arrangement—a developer selling power that's produced right there on the building," says Boleyn. "The utilities no longer have a monopoly on supplying power. Mosier Creek Solar is doing it, and at lower electric rates."

Boleyn says they checked Oregon utility law to make sure that MC Solar would not be considered a public utility and subject to regulation, and acknowledged that the utilities were "quite cooperative in setting everything up, including the net metering agreements."

Erickson is pleased with the outcome and says that highperformance housing offers "distinct marketing advantages

Mosier Creek Homes On-Grid PV System

Inverter: PV Powered PV2880 XV, 450 VDC KWH Meter: maximum input, 200-390 VDC MPPT window, jo utility grid 240 VAC output

Inverter: PV Powered PV2880 XV, 450 VDC KWH Meter: maximum input, 200-390 VDC MPPT window, jo utility grid 240 VAC output

Powered Grid

Photovoltaics: Eighteen Sharp NE-170U1 or NT-180U1, 170 W or 180 W each at 34.8 or 35.9 Vmp, wired in two 9-module series strings for 3,240 W total at 323 Vmp

Note: All numbers are rated, manufacturers' specifications, or nominal unless otherwise specified.

AC Service Entrance:

To 120/240 VAC loads

Photovoltaics: Eighteen Sharp NE-170U1 or NT-180U1, 170 W or 180 W each at 34.8 or 35.9 Vmp, wired in two 9-module series strings for 3,240 W total at 323 Vmp

Note: All numbers are rated, manufacturers' specifications, or nominal unless otherwise specified.

AC Service Entrance:

To 120/240 VAC loads affordable solar

Town House Tech Specs

Location: Mosier, Oregon

Solar resource: 3.9 average daily peak sun-hours

Heating & cooling system: Carrier Performance series, Energy Star-rated heat pump/air conditioning system

Electricity: 3.2 KW grid-tied PV system

Water heating: Solar, with electric backup

Average monthly production, PV system: 366 KWH

Average monthly production, SHW system: 208 KWH

Photovoltaic System Details

Modules: Sharp NE-170U1 or NT-180U1, 170 W or 180 W STC, 34.8 or 35.9 Vmp

Array (per housing unit): Two 9-module series strings, 3,240 W STC total, 323 Vmp

Array installation: UniRac SolarMount, on south-facing roofs, 14-degree tilt

Total PV installed capacity (entire complex): 86.7 KW

Inverters: PV Powered PVP2800 XV, 450 VDC maximum DC input voltage, 200-390 VDC MPPT voltage window, 240 VAC output

Solar Hot Water System

Collector: Sol-Reliant, 56 sq. ft.

Collector installation: Roof mount, south-facing, 14-degree tilt angle

Heat transfer fluid: Propylene glycol

Circulation pump: PV-powered Hartell HEH18

Storage tank: Rheem Solaraide 120-HE/1, 120 gal. (provides SHW storage and backup electric water heating); integrated heat exchanger that protect the developer in a downmarket cycle. In fact, we came online having received our final occupancy permits this past June in the middle of a national slowdown in real estate and have sold ten of our thirty-four units to date."

"The public is very concerned about the rising costs of energy. If a prospective buyer can find a home that is LEED-H certified and produces 50% of its energy needs, then it's an easy decision," says Erickson. "I wouldn't have engaged in the process if it didn't pencil for both us and the home buyer."


Denis Du Bois was hooked on solar energy in 2001 when he installed a PV system at his off-grid summer home. He is CEO of P5 Group Inc., a Seattle firm that helps energy-related companies market successfully. Du Bois founded Energy Priorities magazine and hosts the popular "Energy Minute" podcast series.

Cascade Solar Consulting • 503-6551617 • • RE planning

(continued on page 37)

Solar Incentives for Better Business

Mosier Creek Solar LLC took advantage of three solar-electric and hot water incentives available to businesses:

• Oregon state tax credit: 35% of system cost, no limit. (This has since been raised to 50%.)

• Federal solar investment tax credit: 30% of system cost, no limit.

• Equipment depreciation: 5-year accelerated.

In addition, the Energy Trust of Oregon kicked in $35,000 (the maximum, per project) through two incentives:

• $0.40 per kilowatt-hour of electricity saved for hot water.

The Mosier Creek Homes formula for making PV financially appealing to both developer and buyer:

• Install PV and solar water heating systems on each unit.

• Set up a separate business to own the solar equipment.

• Use business tax incentives and other subsidies to cover as much as 70% of the cost.

• Price the homes at a premium, because of their renewable energy features.

• Sell the solar-generated electricity to the homeowners below retail rates, and let them sell any excess to the utility.

• Consider leasing or selling the equipment to the homeowners, which offers another potential source of profit for developers and investors.

affordable solar

Todd Lefever

Powerfully Efficient Homes

With an estimated total energy load of 13,560 kilowatt-hours per year for each townhome, the combined output of the 3-kilowatt PV array and a 56-square-foot thermal solar collector is expected to supply a little more than 50% of the residence's energy requirement. Doug Boleyn, consulting engineer for the project, says that's impressive for an all-electric home on Oregon's chilly Columbia River Gorge.

But this shouldn't be surprising, given that the Mosier Creek development was built to the highest energy specification. This LEED-certified project features high-efficiency heat pumps, and Energy Star appliances and lighting. Two-by-six studs framed at 24 inches on center conserve lumber and reduce thermal bridging, and R-21 insulation in walls, R-30 in the floors, R-38 in ceilings, and low-emissivity, high-performance windows throughout help ensure each townhome's excellent thermal performance. The townhomes are sited in an east-west orientation to maximize solar gain. In all, the buildings use 30% less energy than energy-efficient buildings of a decade ago.

Besides electricity, the sun also provides domestic hot water via solar thermal collectors.

Mosier Creek Homes Solar Hot Water System

4x14 ft. Sol-Reliant Collector

4x14 ft. Sol-Reliant Collector

Todd Lefever

Single-Tank Solar Hot Water

Manufacturers of the single-tank solar/electric system place a single 240 VAC element about one-third of the way down from the top of the tank. With a 120-gallon tank, this assures at least 40 gallons of standby hot water—even if the sun doesn't shine. The heat in the tall, vertically oriented tank naturally stratifies, with the hottest water at the top. The solar heat exchanger is located in the bottom half of the tank, using the sun's energy to warm the coldest water first.

On a sunny day, the solar gains will exceed the electric element's temperature setting, with solar energy heating the whole tankful of water to 140°F or more. A water heater timer can be used to keep the electric element off during the middle of the day, "prioritizing" solar energy over heating with electricity. (A tempering valve should be installed to ensure that scalding hot, solar-heated water doesn't flow into the hot water service.)

In a single-tank solar-integrated system, solar energy is generally able to achieve temperatures well above the thermostat setting, and the heat lost down to that setting is all solar generated—and all free. The typical standby loss of a two-tank system can be 15 to 20% of the total energy required for the water heating system. In a single tank system, standby losses are about half this amount.

affordable solar

At just under 1,600 square feet, space was at a premium in the two-bedroom townhomes—both inside and on the roof. So the common two-tank solar water heating system— with a solar preheat tank and conventional backup water heater—was abandoned. Instead, a 120-gallon solar tank with built-in heat exchanger and a single upper electric element serves as both the solar preheating tank and backup electric water heater within a single footprint. The tank fits neatly beside the energy-efficient clothes washer and dryer in each townhome's laundry room.

Twenty-eight individual PV systems, with a total installed capacity of 86.7 KW, were installed by Tod LeFevre, P.E., of Hood River, Oregon-based Common Energy LCC. PV Powered inverters, which are manufactured in Bend, Oregon, were specified to synchronize the output of the PV arrays with the utility grid.

On the roof, keeping the solar collectors and PV modules at a low profile was important to the streamlined architecture of the development. The long side-to-side layout of the Sol-Reliant collectors fits nicely with the roof plan and individual PV arrays.

—John Patterson

Common Energy LLC • 541-308-C • PV systems

Mr. Sun Solar • 503-222-2468 • • Solar thermal systems

Mosier Creek Homes •

Surround Architecture • 503-224-6484 • • Architect

Urban Fund Inc. • 206-623-1234 • • Developer

PV & Solar Thermal Systems Components Manufacturers:

PV Powered • 541-312-3832 • • Inverters

Rheem • 334-260-1525 • • SHW storage tank

Sol-Reliant • 888-765-7359 • • Solar thermal collectors

Sharp Solar • 800-765-2706 • • PVs UniRac • 505-242-6411 • • PV mounts

Photovoltaic Module Carrier


betterSOLUTION FASTERinstallation

UniRac Inc. develops, manufactures and supports mounting solutions for photovoltaic (PV) arrays.

UniRac has established itself as a clear leader in its market segment by developing an outstanding reputation for product range, consistency, innovation and partnership.

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  • frankie
    How to integate invertor to load & grid system?
    9 years ago

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