Comment Re:Aren't HPS lights more efficient than LED? (Score 1) 372
High Pressure Sodium street lights are around 100 lumens per watt. HPS can be as low as 50 or as high as 150 depending various factors.
LED street lights are also around 100 lumens per watt, but they vary even more widely.
A theoretically perfect light source with a wavelength of 555 nm would emit 683 lumens per watt, so both LED and HPS are about 15% efficient.
Even the best HPS is less than 25% efficient, and the best LED isn't much better at just over 35%.
At 14.5 lumens per watt, an A19 incandescent 60 Watt bulb (i.e. a "normal" bulb) comes the closest to 97%, but it's 97% inefficient.