Supplemental lighting is most beneficial during November through February in Michigan, when natural light levels are at their lowest. An increasing number of Michigan growers have invested in either high-intensity or low-intensity lighting from light-emitting diodes (LEDs) in order to increase photosynthesis and plant growth or to control flowering. LEDs continue to grow in popularity within the greenhouse industry as their efficiency increases and their initial cost decreases. In a January 2020 article, Erik Runkle provided the efficacy of high-intensity LEDs on the market that met the requirements for the “Qualified Product List” set by the Design Lights Consortium (DLC) in 2018. In order for an LED light fixture to meet the standards, it must have a five-year warranty, photosynthetic light maintenance of at least 36,000 hours, and a minimum efficacy of 1.9 μmol·J–1. The efficacy of a lamp is the amount of photosynthetic light emitted per unit of energy consumed by the lamp. As of February 2021, there were more than 280 LED products that met those standards.
While the initial cost of installing LEDs, especially high-intensity LEDs, might still not be economical, Michigan State University Extension recommends that greenhouse or controlled-environment agricultural crop producers reevaluate the costs of an installation frequently. The technology continues to evolve rapidly and costs continue to decrease. In addition, Michigan utility companies such as DTE Energy and Consumers Energy offer rebates and incentives for installing energy-saving technologies, including supplemental lighting.
For DTE Energy electric customers, DTE has recently launched the DTE Energy Grow Energy Efficiently Pilot Program for lighting upgrades. DTE will help producers identify which new LEDs qualify for the incentive program. Greenhouse owners who install these energy-efficient LEDs could save $0.05 per kWh.
According to Lindsay Buckwell, program manager for Evergreen Efficiency on behalf of DTE Energy, "The Grow Energy Efficiently pilot program team is happy to continue to offer customers the current DTE prescriptive incentive rates and provide specialized customer support to help accelerate energy efficiency." DTE Energy Electric customers who are interested in the program can learn more about by viewing the “2021 Grow Energy Efficiently Pilot Program Application and Agreement.”
Consumers Energy has also released their 2021 Incentive Catalog. In the catalog, producers can find the requirements of agricultural LED lamps that qualify for incentives under “LED Grow Lights” on page 74. In addition to the 2021 incentives, Consumer’s Energy is also running a 10% savings on qualifying projects that are received during the first quarter or before March 31, 2021. For more information on the bonus program, check out, “Early Bird Bonus – Q1 2021.”