Page 59 - Solar Power in Building Design The Engineer's Complete Design Resource

AMONIX MEGACONCENTRATORS 29

3 Hydraulic subsystem. Applies hydraulic pressure to one side of the hydraulic actu-
ators to move the torque tube and MegaModules in elevation and azimuth in order
to keep the system pointing at the sun. The hydraulic system consists of hydraulic
valves, an accumulator, a pump, a reservoir, and pressure sensors.
4 Tracking control subsystem. Monitors sensors on the system, calculates the required
movement for the commanded operation, and applies signals to the hydraulic valves
to move the system to the commanded position. The commanded position could be
to track the sun, move to a night stow position, move to a wind stow position, or
move to a maintenance position.
5 AC/DC control subsystem. Combines the dc power, converts it to ac power, and
interfaces with the ac grid. It consists of dc fuses, circuit breakers, and an inverter.
6 Control mechanism. Sun-tracking platforms to be described later, results in addi-
tional annual energy generation per installed kilowatt. The average annual energy
test of Mega Concentrator installations in California and Arizona have augmented
50 percent more power output than comparable fixed flat-plate installations.

CONCENTRATOR OPTICS
Refractive optics is used to concentrate the sun’s irradiance onto a solar cell, as illus-
trated in Figure 2.8. A square Fresnel lens, incorporating circular facets, is used to turn
sun rays to a central focal point. A solar cell is mounted at this focal point and con-
verts the sun power into electric power. A number of Fresnel lenses are manufactured
as a single piece, or parquet.
The solar cells are mounted on a plate, at locations corresponding to the focus of
each Fresnel lens. A steel C-channel structure maintains the aligned positions of the

Figure 2.8 Fresnel lens concentrator.