PROJECTS: SOLAR TRACKER
5j. All the pieces are built; the last step is to add more velcro so
they store together easily. Arrange the PV cell, shade, and brass
tube on the underside of the turntable disk near the edges, and
velcro-tape them in place. Go for convenience; you shouldn’t
have to disassemble the base to reach these parts. I store the
PV cell velcroed to the shade between the free wheels, and use
3 tabs of velcro to hold the brass rod. The coupling nut and
screw stow screwed into the retracted boom.
6. TEST AND ADJUST
6a. On a sunny day, secure the base onto the central axle with
the nuts, washers, and stop nut, and then turn the platform right
side up. Extend the boom, wrap 2 or 3 turns of the red and black
wires around it, and mount the PV cell and shade as in Step 4f.
6b. Place the platform on a flat surface in the sun and orient it
so that the entire PV cell is illuminated. If the wiring is correct,
the turntable should rotate clockwise until the surface of the PV
cell is only partially illuminated. Tracking has begun! But if the
turntable rotates counterclockwise (and you’re in the Northern
Hemisphere), you need to swap the motor connections. Solder
them when they’re correct, and cover them with electrical tape.
6c. To determine the platform’s central tracking angle — its
optimum orientation — install the brass tube (the gnomon) in its
hole and position the tracker so that its PV cell is fully lit by the
sun. Watch it for several cycles, noting the shadow’s positions
on the protractor when the motor starts and stops. The average
between these 2 readings is the central tracking angle.
This number varies depending on the time of year, so it’s a good
idea to recalibrate if you haven’t used the cooker in a while.
You’re done, and ready to maximize some solar energy!
FINISH X
110 Make: Volume
22
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