Thursday, August 27, 2009

Solar Knowledge: What is an Array Mounting Rack

Array Mounting Rack
AKA: mounts, racks

Mounting racks provide a secure platform on which to anchor your PV panels, keeping them fixed in place and oriented correctly. Panels can be mounted using one of three approaches: 1) on a rooftop; 2) atop a steel pole set in concrete; or 3) at ground level. The specific pieces, parts, and materials of your mounting device will vary considerably depending on which mounting method you choose.

Usually, arrays in urban or suburban areas are mounted on a home’s south-facing roof, parallel to the roof’s slope. This approach is sometimes considered most aesthetically pleasing, and may be required by local regulators or homeowner’s associations. In areas with a lot of space, pole- or ground-mounted arrays are another choice.

Mounting racks may incorporate other features, such as seasonal adjustability. The sun is higher in the sky during the summer and lower in the winter. Adjustable mounting racks enable you to set the angle of your PV panels seasonally, keeping them aimed more directly at the sun. Adjusting the tilt angle increases the system’s annual energy production by a few percent. The tilt of roofmounted arrays is rarely changed. Adjusting the angle is inconvenient and sometimes dangerous, due to the array’s location.

Changing the tilt angle of pole- or ground-mounted arrays can be done quickly and safely. Pole-mounted PV arrays also can incorporate tracking devices that allow the array to automatically follow the sun across the sky from east to west each day. Tracked PV arrays can increase the system’s daily energy output by 25 to 40 percent.

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