Page 24 - North American Clean Energy September/October 2019 Issue

solar energy
The
Revolution of
Sun Tracking
Carports
by Alain Poivet
Commercial size carports are often the easiest solution to deploy large areas of solar collectors in an urban area or on corporate sites, but these fixed carports have a major flaw; because they usually follow the drive lanes azimuth, they are often sub-optimally oriented and, therefore, less than efficient.
Keep an eye out for the latest standard: Sun-tracking carports. This new technology is about to reshape the industry.
Parking areas are perfect applications for solar deployment. They are large areas with little shading and no building integration issues. The solar panels installed on canopies above the parking spots shade the cars, which protects them and reduces the need for air conditioning. Solar carports or canopies are now widely used in sunnier parts of the world, but these are usually fixed and can rarely be ideally oriented. Additionally, in order to remain economically feasible, they must follow the parking lot’s layout, which means that their orientation is usually controlled by the drive lanes azimuth - often less than optimal.
Fixed carports are often built with a 5 to 10-degree pitch. This may be acceptable when facing south (although the ideal pitch would be 20-25 degree), but few parking lots have a perfect southern orientation. Most of the time, the panels are going to face an awkward azimuth, severely reducing efficiency. Plus, if the panel faces the sun at 2pm (at a 30-degree tilt), it is 15 degrees off at 1pm, 30 degrees off at noon, and 90 degrees off at 8am. At 8am, no direct sun ray hits the solar collector surface; it collects no energy except for some reflected glare, although most of the year the sun is already powerful at 8am. At 3pm it is 15 degrees off, and at 6pm it is 60 degrees off. Designers try their best to set this fixed angle so their panels are tilted towards the south in the northern hemisphere and north in the southern hemisphere, but these other tilt angles all have the same problem: the losses are enormous.
Fixed carport designers look for a compromise between pitch, clearance, cost, and efficiency. Ideally, if they could use a carport technology that allowed the
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SEPTEMBER•OCTOBER2019 /// www.nacleanenergy.com