The basic idea of this project was to turn off a number of lights in a convenient store when the ambient sunlight is sufficient to keep the brightness level above the store's minimum brightness standard. Here's a diagram of the system 
The main compenents of this project are as follows:
- Three ambient light sensors were used. Two were place inside the store at the darkest locations to verify that the brightness levels never drop below the minimum standard. The third sensor was place outside to detect when there is sufficiet sunlight.
- Three relays were used to control three sets of light bulbs. Each set consists of six bulbs. The brighter the ambient light, the more bulbs were switched off to conserve energy.
- A USB web cam was attached to the Raspberry Pi and used to capture photos of the store lights in action.
- A 3G Aircard was used to allow the sensor values and light status to be viewed remotely on a web browser.
Here are some photos of the system
Control Box. The Raspberry Pi and PiTopping is shown in the top part of the control box. A USB 3G aircard is used to access the data online. Relay switches in the middle row were installed to control the store lights.
A USB webcam was used to snap photos of the light bulbs and make the photos available online.
Two light sensors was placed on one of the store shelves.
A light sensor being installed outside the store to determine the amount of sunlight outside.
For more detail: Energy Saving in a Convenient Store
