LED vs HPS ...
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LEDs Versus HPS Lamps
The ideal lighting system for cannabis growth is difficult to determine as both LEDs and HPS each have their respective advantages (
Viršilė et al., 2017). For large scale of production with uniformly spaced plants, HPS provides a broader uniform light distribution that can cover a larger area of production than LEDs (
Nelson and Bugbee, 2014). However, LEDs can be optimized to specific production conditions by controlling periodicity, quantity, and spectrum of the light provided (
Pinho et al., 2007). LEDs allow high-density production systems to have a focused spectral quality that can maximize radiation transfer to plants (
Nelson and Bugbee, 2014). Their low heat emission allows them to be placed in the plant canopy for maximum cannabinoid yields (
Viršilė et al., 2017;
Hawley, 2018).
Based on the cost analysis, photon efficacy, and capital costs of fixtures per photon delivered, it has been determined that LED fixtures cost five to ten times more than HPS fixtures, and that current, efficient fixtures available in the US have nearly identical efficiencies of 1.66–1.70 μmol J−1 (
Nelson and Bugbee, 2014). The same study showed that both technologies have relatively low long-term maintenance costs. Dutch and Danish LED fixtures with efficiencies of 2.2–2.4 μmol J−1 are available in Europe, whereas the newest HPS lamps (1,000 W) reach up to 2.1 μmol J−1, indicating that LEDs are fully implementable on a commercial scale (
Ouzounis et al., 2015).
