There are many energy efficiency measures that can help a business or organization save money and switching to LEDs is one of the first things to look at.  There are four advantages to LEDs:

• Advantage #1:  LEDs use 50-75% less electricity than traditional lighting
• Advantage #2:  LEDs last 10 times longer than traditional lighting technologies, and 5 times longer than fluorescent tubes
• Advantage #3:  LEDs provide a dramatically better quality of light compared to traditional lighting
• Advantage #4:  LEDs help the environment by reducing harmful emissions and the disposal of used traditional bulbs, many of which contain toxic substances

Finally, if you size solar based on the building energy usage before energy efficiency, then you could run the risk of significantly over sizing the system.