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led controlled lighting
Nov 30 2020

Photocells for LED Lights

Daylight harvesting and Photocell controls have a huge benefit for building and lighting controls, but do you know the difference between these two common energy efficiency terms?


Photocells have been around for a long time. These are light sensors that have an internal circuit break inside – meaning they turn off the flow of electricity when there is enough light detected.

Commonly used in external lights, photocells can save energy by turning off lighting during the day. Photocells can be on each individual light, or have one central photocell to operate all lights.

Time clocks are a similar tool used to keep lights off during the day, but photocells have several advantages.

First, you can often adjust the sensitivity of a photocell, allowing exterior LED and standard HID lights to come on during a dark storm. Many national chains and restaurants prefer this to allow their stores to look like it is open even on the darkest day.

Second – getting the exact time of sunrise and sunset is not hard – but it is rare to see a timer clock psyched and operating correctly. More often than not, the loghts are coming on an hour early and wasting live on the fixture and energy.

photocell control system

Daylight Harvesting Controls

Daylight harvesting controls are an entirely different energy efficiency tool, typically used on interior fixtures. These controls are similar to photocells, but instead of simply turning on or off a light, it will dim the fixture when light is available from ambient light.

These controls are an advanced energy efficiency tool, and typically require a higher end driver that can dim on a smooth level of control. We find Signify and Philips Control systems to have the best functionality for this daylight harvesting, but there are many brands.

Daylight harvesting can be on the fixture level of control, or can be grouped together on master interior sensors. Anytime you dim a LED fixture, while the savings is important, the heat taken off the LED driver is even more important and will lengthen the life of the fixture.

daylight control sensor on led

How to Pay for Advanced Lighting Controls

Local utility rebate systems, designed to help reduce energy in a state, can help pay for improvements like photocells and advanced daylight harvesting. Check with your local utility, or as Verde if we can help.


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