We tested a new, double-ended, 1000-W HPS fixture from PARsource (Petaluma, CA). Measurements in an integrating sphere indicate an efficiency of 1.76 micromoles per Joule at an input voltage of 208 V and an efficiency of 1.77 micromoles per Joule at 240 V.
These measurements indicate no significant change in efficiency with input voltage. This finding may apply to other DE-HPS, electronic-ballast fixtures. (Greenhouses with 3-phase power have 208 volts; greenhouses with single phase power typically have 240 volts).
This fixture has an open luminaire similar to the ePapillion fixture, and thus has a broad photon distribution. The manufacturer’s suggested retail price is $599. The company has plans to release this DE-HPS lamp with a more focused luminaire. They also plan to release a version that operates on 120 volts.