Getting the most out of your PV panels Solar Trackers Getting the most out of your PV panels

Why Track? The most energy is absorbed when a surface’s face is perpendicular to the sun Stationary mounted PV panels are only perpendicular to the sun once a day Improved performance from each panel means fewer panels are needed

Types of Trackers: Passive Made by Zomeworks and UniRac Powered by a balancing material, usually Freon, shaded from and heated by sun Panels turn as vapor shifts from side to side

Advantages/Disadvantages No electrical parts Reliable Simple Cost competitive to stationary mounts Morning wake up Slow to react Sluggish in cold weather More expensive to ship Prone to wind gusts

Types of Trackers: Active Made by Array Technologies (as Wattsun), SolarTrax, and Small Power Systems Power by electricity (usually directly from panels) Optical Light Sensor Timer

Advantages/Disadvantages Precise Dual axis Return to sunrise position for earlier start Ignore temperature Shipped in parts Less reliable Sensitive to lightning Higher initial cost Uses electricity, but only about 5 watts per day

How Much More? Extra energy depends on location and site Most beneficial with sunup to sundown solar window

Prices Wattsun complete 2 kW grid-tie system: $18,995 at www.wattsun.com/internet_only_special.html Zomeworks through Vermont Solar $612 - $2,312 for mounting pole only at www.backeastsolar.com Available at most internet stores that deal in PV panels

Do sunflowers really follow the sun? When the plant is in the bud stage, it tends to track the movement of the sun across the horizon. Once the flower opens into the radiance of yellow petals, it faces east. No one knows why. However, it is likely a defensive response. Facing south or west could result in sun-scalding of seeds during very hot days.