Wireless Sensor and Actuator Networks for Lighting Energy ...

As the wireless platform will be made compact by integrating all components
into a single chip, the only element that may not be further integrated and is not
showing strong potential of price reduction is the optical component for the
photosensors, i.e., the photodiodes. The photodiodes are estimated to stay at the range
of $10-$15 per piece. Figure 9-33 shows the impact of the photodiode unit price on the
payback period of the lighting system. It is assumed that the unit price of the dimmable
ballasts is $40, and 60% average energy savings is attained by the system. The payback
time of the lighting system does shorten with the price drop of photodiodes, but is not as
cost-sensitive as with that of dimmable ballasts. This again verifies that the price of
dimmable ballasts dominates the payback period of the proposed lighting system.
Figure 9-33 Photodiode unit prices vs. payback periods.
Lastly, the relationship between the unit price of the wireless platforms and the
payback periods is presented in Figure 9-34 assuming that the dimmable ballasts are
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