Grow light cost calculator
Lights are usually the biggest line on a grow room's electricity bill. Enter what they draw and what you pay, and see the cost of a whole cycle, a day in each stage, and the heat the room has to get rid of.
Nearly every watt a light draws ends up as heat in the room. Add it to the other loads when sizing air conditioning.
How it is calculated
Energy is power times time. Kilowatt-hours for one stage:
kWh = W × fixtures × dimmer % ÷ 100 × hours × days ÷ 1000
cost = kWh × price per kWh
Heat, in the unit air conditioners are sold by:
BTU/h = W × 3.412 · 1 ton of cooling = 12,000 BTU/h
The dimmer setting is an approximation. An LED driver's draw falls close to in step with dimming, but not exactly, and older HID ballasts do not dim the same way.
Getting the inputs right
- Use the power at the wall, not the LED chips' rating. A plug-in power meter costs little and settles it
- Use your tariff's price per kWh including taxes and standing charges spread over use, if your bill has them
- If your tariff is cheaper at night, run the lights then: the cost falls and the room stays cooler in the day
Status: Cultidock switches lights on schedules from the app; that works in software with sample data, and the controller does not drive outputs yet. Dimming from the app (0 to 10 V) is planned. All features and their status