AnyponicsPlanning · Running costs
How much electricity does hydroponics use?
An indoor hydroponic system for a household's worth of lettuce uses about 110 kWh a month — roughly $18 at $0.16/kWh. About 89% of that is the grow light. The pump, which people worry about, runs all day on less power than a light bulb.
Electricity for six real designs
| Setup | System | Plants | Power /mo | Electricity /mo | Running /mo |
|---|---|---|---|---|---|
| Herbs, 2×3 ft counter | DWC | 8 | 110 kWh | $18 | $21 |
| Lettuce, 8×10 ft, household | DWC | 40 | 110 kWh | $18 | $30 |
| Lettuce, 8×10 ft, as much as fits | DWC | 224 | 308 kWh | $49 | $117 |
| Microgreens, 4×4 ft rack | Microgreens Tray | 11 | 140 kWh | $22 | $56 |
| Tomatoes, 4×4 ft | Drip | 11 | 98 kWh | $16 | $18 |
| Greens in a greenhouse (sunlight) | Vertical Tower | 40 | 12 kWh | $2 | $14 |
How to work it out yourself
Electricity is watts × hours ÷ 1,000 = kWh, then kWh × your rate. For the household lettuce design:
- Light: 200 W × 16 h = 3.2 kWh a day.
- Pump and air pump: 17 W × 24 h = 0.4 kWh a day.
- Total: 3.6 kWh a day × 30.4 days = 110 kWh a month.
Use the wattage the light actually draws (on the label or a plug-in meter), not the "equivalent" wattage some listings advertise.
Three ways to cut it
- Use sunlight. The greenhouse row above runs on about 12 kWh a month because the lights are gone. Even a few summer months outdoors makes a dent.
- Don't over-light leafy greens. Lettuce is happy at about 200 µmol/m²/s. Lights sized for tomatoes waste power on greens.
- Buy an efficient LED. Modern LEDs make about 2.6 µmol of light per joule; older fluorescent and HPS fixtures make 1.0–1.7, so they cost up to 2.6 times as much to run for the same light.
Lights and pumps both add heat, about 3.4 BTU per watt. In winter that offsets some heating; in summer, a little more cooling.