Total BOS & BOS Labor Total Installed Cost

$1,886.00 $8,645.34

*306.4 sq. ft. of net absorber area

*306.4 sq. ft. of net absorber area

This was a small installation in the scale of projects by SMC. The costs were kept down and the efficiencies maximized because of SMC's experience with large solar projects. SMC specializes in solar heating for commercial and industrial applications, mainly in the mining industry.

Money & Energy Savings

How much energy has the system saved? So far, only estimates can be given. The collectors have never been above 120°F (49°C), and always operate in temperatures just above the floor temperature. A conservative estimate for operating at these lower temperatures is about 160 to 180 thousand BTUs per day produced.

Propane heating appliances have an average output efficiency of 72 percent, and on average produce approximately 66,000 BTUs of useable heat per gallon of propane burned. The system will save about 3 gallons (11 l) of propane per day, with a conservative estimate of performance, and probably more. That may not sound like much, but depending on the volatile price of propane at any given time, it can amount to a savings of US$1,000 or more per year. The avoided emissions and lowered dependence on fossil fuels are the icing on the cake. Maybe they are the cake...

Operation & Maintenance

The operation of the system is completely automatic. The differential controller runs the system whenever the sunshine is sufficient. The controller is an Independent Energy C-100, which has five digital temperature readouts to monitor the collector inlet and outlet, storage tank, heat exchanger, and slab temperatures. The thermostat fires up the propane heater when there is not enough solar energy.

With the collector temperature below 120°F (49°C), the glycol solution will probably last a decade or two. The pumps will need replacement someday, but they also will have an enhanced lifetime with the lower fluid temperatures. The collectors are self-cleaning with each rainfall, and there is plenty of that in Green Bay. When the greenhouse gets too warm, automatic actuators open the windows, and the plants love the fresh air.

The end use of any solar heating system can dramatically affect how much the system produces. Heating a building or water to temperatures needed for human comfort are by far the most common uses. But other commercial and industrial applications that need less heat are out there, waiting for a little help from the sun.


Richard Lane, Solar Mining Company, 4226 Whisper Ln., De Pere, WI 54115 • 920-983-7610 • Fax 920-336-3914 • [email protected] • Commercial and industrial solar heating equipment & projects

Chuck Marken, AAA Solar Supply Inc., 2021 Zearing NW, Albuquerque, NM 87104 • 800-245-0311 or 505-243-4900 • Fax: 505-243-4900 • [email protected] • Solar energy equipment manufacturer & distributor

Jill Martus-Ninham, Tsyunhehkwa, PO Box 365, Oneida, WI 54155 • 800-236-2214 or 920-869-2718 • Fax: 920-8692147 • [email protected]

Bill Hurrle, Community Builders, 4280 Algoma Rd., New Franken, WI 54229 • 920-886-9204 • [email protected] • Photos courtesy of Bill, an SMC solar tech

Goldline Controls, Inc., 42 Ladd St., East Greenwich, RI 02818 • 800-294-4225 or 401-884-6990 • Fax: 401-885-1500 •

solar hydronic greenhouse

[email protected] • Differential controls

Taco, Inc., 1160 Cranston St., Cranston, RI 02920 • 401-942-8000 • Fax: 401-942-2360 • [email protected] • Hydronic circulating pumps

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