Our shop utilizes its own 2.5 kw array and 35 kw battery bank for daily power needs and testing of new products.

^Vhether you are looking for one module or a 90-module state of the art, turn key system — Sunelco can be of help.

Sunelco puts the customer first. We offer fast service, factory trained technicians, personal assistance and answers to your questions.

Our large inventory and factory direct distributorships allow us to provide our customers with good pricing and excellent service. We stand behind the products we sell!

• Comprehensive selection of solar and system related components

• Experienced, professional technical assistance

• Support unsurpassed in the solar industry

• Largest inventory and the fastest shipping department in the industry allows shipping in 24 hours if not the same day.

For the home owner who is working with an Architect or Contactor, we can work directly with your technical people. As well, our installation crew can handle the complete job, just like your plumber or roofer.

THE SUN ELECTRIC CO. P.O. Box 1499HP • Hamilton, MT 59840

THE SUN ELECTRIC CO. P.O. Box 1499HP • Hamilton, MT 59840

order line 1-800-338-6844

technical assistance line 1-406-363-6924

SOLAR ELECTRIC INC camera ready b&w 4 wide 2.25 high

Solar and Propane-Powered Home

When most people think of an alternative energy home they think of a small cabin in the woods without modern conveniences. This solar home located in rural Virginia quickly dispels this myth as it includes a state-of-the-art automation control system, a whole house stereo system, a home video theater with six channel sound, whirlpool, and the most energy efficient appliances and lighting fixtures that are available today.

Home Design

The three story compact design consists of 3,000 square feet, plus an adjoining passive solar greenhouse, screened porch, and three level deck. The insulated, concrete slab ground floor with masonry walls is three feet below grade. This level includes the battery and control room, utility room, music room, home theater room, bathroom, and the greenhouse. The main floor has a double envelope exterior wall consisting of two 2x4 walls separated by 6" batt insulation and finished with tongue and groove cedar. This level includes a cathedral ceiling living room, kitchen, guest bath, and two guest bedrooms.

The upper loft includes a large master bedroom, master bath, and a balcony study overlooking the living room. All windows are double-glazed, low "E" glass filled with argon gas. The skylights and solar blinds are motorized and can be remotely operated.

Heating System

The home has a 500 gallon underground propane tank serving high efficiency electronic ignition propane appliances. These include a six burner commercial stove, clothes dryer, propane fueled back-up generator, and a hot water heater which heats domestic hot water and supplies a space heating coil in the air handling unit.

Space heating is helped by a closed-loop water jacket in the wood burning fireplace which supplies a second heating coil in the central air handling unit. When space heat is required and the fireplace loop is not hot, the controls stop the fireplace loop pump and start the heating loop served from the domestic hot water tank. The greenhouse is heated by passive solar and requires no back-up heating.

The air handling unit fan distributes heated air throughout the house. Although this fan requires more energy to operate than a heating system using baseboard radiation, it was a design trade-off to move air from the cooler ground floor rooms to the warmer upper rooms. When the air handling unit was installed, the fan motor was discarded and replaced with a high efficiency motor. A freestanding Franklin style wood stove with an exposed flue is located in the high ceiling living room. This wood stove can also heat the house without additional fans or pumps.

Cooling System

The air handling system also has a cooling coil connected to an extremely efficient exterior air conditioner. The air conditioning system is wired to the utility breaker panel to avoid over-loading the generator or solar battery storage system. Due to the heavily insulated walls and windows, the air conditioner only needs to operate a few weeks each summer.

Since the home was located on a wooded hill of a lakefront development, natural cooling is provided by opening the lower basement windows and upper loft windows and skylights to create a natural draft. In addition, all three bedrooms include an efficient ceiling fan. Since all windows are located under large roof overhangs, almost all the windows are shaded during the summer months to reduce cooling requirements.

Generator System

Powering a home this size by photovoltaics alone would not be cost effective. To keep costs down, this home was designed to use propane gas for heating and hot water needs when the fireplace is not being used. On days we anticipate a large electrical demand, the seven kw propane-fueled generator is started to power the heavier loads including the clothes washer, clothes dryer motor, dishwasher, and whirlpool.

Any time the generator is operating, it is also used to power a battery charger to supplement solar charging. This method of control insures the generator is always operating at full load, and allows having the luxury of time-saving appliances without draining the batteries. By scheduling these periods of heavy loads during an evening and/or after several days of cloudy weather, the generator provides battery charging when needed most.

Circuits and Transfer Switching

We wanted the power transfer between the inverters, generator, and utility to be as simple and reliable as possible. We designed a control cabinet with two double pole transfer relays and low energy LED panel lights to graphically illustrate the position of each relay.

Red LEDs are used to indicate all non-normal switch positions and green LEDs are used for normal position. Any lighted red LED on the panel indicates something has changed from normal operation and needs attention. The 110/220 volt main circuit panel at the utility feed has circuit breakers for the driveway lighting, pool filter, air conditioning unit, and a 60 amp-220 volt sub-feed to the first transfer switch. This switch transfers to the propane fueled 110/220 volt generator when it is started.

The first double pole transfer switch feeds the second transfer switch and a separate generator circuit breaker panel. This panel supplies all large appliance motors which can only operate when either the generator is operating or the main utility service breaker is manually switched on.

The second double pole transfer switch transfers both lines from the first transfer switch feed to two separate TRACE 2524 inverters anytime this feed has no power. The first inverter supplies the wall outlet circuit breaker panel which feeds most of the smaller kitchen appliances, audio/video equipment, and anything plugged into wall outlets.

The second inverter feeds all lighting circuits not wired for 24 Volt DC operation and the well pump. This second circuit reduced earlier problems with the loss of all lighting when the inverter was temporarily overloaded by too many appliances operating at one time.

Although this switching can be manually controlled, all of the above operations are normally automated by relay logic without electronics.

Low Voltage Power

The 24 Volt DC breaker panel is supplied directly from the battery to the DC lighting and appliances without any further controls. These loads include all fluorescent corridor and stair lighting, the refrigerator, the freezer, a back-up 24 Volt DC well pump, and the exhaust fans in the greenhouse and attic. All fluorescent lighting fixtures powered by the system had their magnetic ballasts replaced with 24 Volt DC electronic ballasts.

The solar array is 32 ARCO M-51 solar panels with a seasonally adjustable mounting. The panels are wired in series-parallel to provide 24 Volts to the battery through a Heliotrope General 60 Amp charge controller.

Appliance Controls

Since RE homes have a fixed energy capacity, it was important to install high efficiency appliances and lighting. A computer system running programmed usage schedules and using room motion sensors operates the lighting, heating, and sound systems for each room. For convenience, everything can be manually controlled be entering codes from telephones located in every room or remotely when away.

Lighting Design

In order to keep the number of solar panels to a minimum, we took great care with lighting design, which can use as much as 1/3 of a home's electrical demand. Each lighting fixture and lamp type was specifically selected for the intended location and use.

There are no conventional incandescent bulbs anywhere in this house. High ceiling areas requiring recessed lamps were fitted with low wattage halogen reflector bulbs. Almost all of the remaining lighting is 34 Watt fluorescent tube and 13 Watt compact fluorescent ceiling lights with electronic ballasts. The fluorescent lighting was selected in the 3000 to 3500K color temperature range to provide a warmer light than found with most cool white fluorescent lamps.

If every light fixture was operated at the same time, it would be less than 1/2 Watt per square foot. This is far below the typical 2 to 3 Watt per square foot of most homes and offices. Once this lighting and appliance electrical load was reduced to the minimum, it was then possible to design and size a more cost-effective solar system.

Although this home is connected to the utility grid for air conditioning and back-up needs, we are not affected by grid power outages which are more common and last

Above: Transfer Switch and Controls: The use of graphics and LED lights makes it easy to spot any electrical problems longer with our rural electrical service. Only weeks after moving into this home, an ice storm left our county without electrical service for seven days. We were the only home with electricity. We provided many five gallon cans of water each day to area residents having wells with electric pumps. It may be possible to get by with flashlights and wood stoves, but it is very difficult to live without running water for drinking, bathing, cooking, cleaning, and flushing the toilet.


We have lived in our home almost two years and have enjoyed the peace of mind knowing our home will take care of us, but I do not feel an alternative energy home is right for everyone. This style of living requires careful scheduling of energy usage, awareness of local weather conditions, daily checking on battery charge state, and periodic servicing of the batteries and generator. Most homeowners want the lights and television to operate when they turn the switch and do not care where the electricity comes from until it stops. We feel almost every home should include at least some of the features we have described to reduce energy usage and allow a family to remain comfortable through a power interruption. Today a power outage lasting over one day becomes a national disaster and can become life threatening for many. It does not need to be that way.

Award Winner

This solar home has won many awards including; first place in the 1992 and 1994 annual energy awards sponsored by the Virginia Division of Energy and the Virginia Propane Dealers Association respectively; and was one of nine finalists selected from all fifty states in the energy awards competition sponsored by the National Propane Dealers Association at their 1995 convention in Dallas.


Mr. Yago is a licensed professional engineer and president of J.R. Yago & Associates, a consulting engineering firm located near Richmond, Virginia. He has been involved in solar and energy reduction design since the early 1970's and has completed many projects in the United States and Europe. Phone 804-457-2113

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