Swiss Solar Tech: Okanagan College Centre of Excellence
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To provide students with the opportunity to compare technologies and relative system performance, Okanagan College’s solar water-heating system utilizes both flat-plate and evacuated-tube collector technologies. The hot water generated is used for domestic water and space heating. At the time of publication, Swiss Solar Tech had installed and commissioned Phase One of the system, composed of 18 flat-plate collectors. Phase Two will include the addition of eleven 30-tube evacuatedtube collectors. A direct digital control system transfers data such as collector temperatures, storage tank input and output temperatures, and energy production to a website for performance evaluation.
Swiss Solar Tech installed the collectors on custom-engineered racking. Unlike the PV arrays, the thermal collectors were installed at a more traditional 45° tilt angle to maximize energy production during the seasons of highest hotwater demand. Roof curbs were specified by the engineers and incorporated into the building and racking design. Because the system’s storage tanks are located in the building’s central mechanical room, the pipe run between the collectors and the tanks needed to be 148 feet. To minimize heating losses, this design required special consideration during the thermal system installation.
“Given that the PV and thermal systems were included in the original building design and all the various trades worked together, our installation was fairly smooth. The biggest challenge was coordinating all the aspects of construction to meet the federal government’s deadline for the incentives.”
—Tim Schulhauser, P. Eng., SkyFire Energy
DESIGNER: Roger Huber, CEO, Swiss Solar Tech, swisssolartech.com
LEAD INSTALLER: Richard Steuble, Swiss Solar Tech
ANNUAL HEATING DEGREE-DAYS: 3,431 base 65°F
RECORD LOW TEMPERATURE: -17°F
COLLECTOR ARRAY AREA: 450 sq. ft. (flat-plate collectors), 512 sq. ft. (evacuated-tube collectors, gross area)
AVERAGE ANNUAL PRODUCTION: 73.2 MWh
Thermal Equipment Specifications
COLLECTORS: 18 Viessmann Vitosol 200-F flat-plate, 11 Viessmann Vitosol 200-T evacuated-tube
HEAT EXCHANGERS: Two Advanced Industrial Components (AIC) LB3120DW
PUMPS: Grundfos UPS26-150
STORAGE: Eight Bradford White 120-gallon tanks
CONTROLS: ESAA Boehringer SONJA SR-5
FREEZE CONTROL: Closed-loop glycol
COLLECTOR INSTALLATION: Lowslope roof, single-ply membrane, custom collector array mounts, 180° azimuth, 45° tilt
SYSTEM MONITORING: Direct digital control (DDC) with web-based data transfer