Greenhouse, Indoor Farming & Agri-Processing worked example

Grow Light Energy Cost at 69% effective lit hours over the period: a worked example

Push effective lit hours over the period up to 69% and the picture changes. This example computes every intermediate figure at that operating point. Use it when you need to budget grow light electricity for a leafy green, herb, microgreen, tomato, or cannabis room, compare an LED retrofit against existing HPS, or check whether a rate change makes a current photoperiod uneconomic.

The inputs for this scenario

  • Total connected grow light load: 65 kW (unchanged)
  • Cost per kWh of electricity: 0.12 $ / kWh (unchanged)
  • Effective lit hours over the period: 69 % (raised for this scenario; the documented default is 60)
  • Fixed demand and meter charges: 250 $ (unchanged)

Working through the calculation

  • Applying the documented formula (Variable lighting energy cost = total connected grow light load × cost per kWh × effective lit hours over the period) to the inputs above produces each figure below.
  • At this operating point the engine returns 255 $ for total grow light energy cost, the number this scenario is built around.
  • At this operating point the engine returns 3.93 $ / piece for lighting cost per kw of canopy.
  • At this operating point the engine returns 5.38 $ for variable lighting energy cost.
  • At this operating point the engine returns 250 $ for fixed demand and meter charges.

How this compares with the baseline

  • Against the tool's baseline example, where effective lit hours over the period sits at 60% and the headline result is 255 $, this scenario lands almost exactly on the baseline at 255 $.
  • It computes total grow light electricity cost by adding the variable energy cost (connected load times rate times effective lit-hour share) to fixed demand and meter charges. The value of this scenario is the size of the gap it exposes: that gap, priced out over a year, is the budget you can justify spending to close it.

Results at a glance

  • Total grow light energy cost: 255 $ (headline result)
  • Lighting cost per kW of canopy: 3.93 $ / piece
  • Variable lighting energy cost: 5.38 $
  • Fixed demand and meter charges: 250 $

Run it with your numbers

  • Every input above is editable in the live Grow Light Energy Cost calculator, which recalculates instantly and can be shared with the inputs intact.

Last reviewed 2026-05-12.