High Pressure Sodium Lights (HPS) have been the standard for streetlights for years. However, the industry - and cities along with it - are moving in the direction of residential LED streetlights. LEDs use less energy and require lower operating costs.
Currently, Dakota Electric is working with the City to start converting residential streetlights to LED. Several neighborhoods have already been converted. Xcel Energy has also converted many major intersection lights to LED within the City.
Light Emitting Diode (LED)
High Pressure Sodium (HPS)
|Cycling||Respond instantaneously. No warm-up or cool-down periods needed.||Require a noticeable warm-up period that ranges from half a second to several minutes depending on the light.|
|Costs||Relatively high initial costs and low lifetime costs. LED has virtually zero maintenance costs||Relatively cheap to purchase, but expensive to maintain. Bulbs require several re-lamping and potential ballast replacement throughout the life period of an LED.|
|Efficiency||Most values for LED system efficiency fall above 50 lumens/watt.||Most values for HPS/HID system efficiency fall below 30 lumens per watt.|
|Shock Resistance||LEDS are solid state lights (SSLs) that are difficult to damage with physical shocks.||HPS/HID bulbs are relatively fragile. More importantly, broken bulbs require special handling and disposal due to hazardous materials like mercury inside of many lights.|
|Emissions||LEDs produce a narrow spectrum of visible lights without the losses to irrelevant radiation types (IR or UV).||Produce relevant amounts of both IR and UV radiation.|
|Light Color||Produces a true white light and is available in a range of color temperatures.||Produces a yellowish color.|
Click here for more information on the differences between LED and HPS/HID lights.