Indoor Farming Energy Costs: What to Expect

A typical home indoor farm with 400W of LED lighting costs $20–35/month in electricity. Energy is the dominant ongoing cost for indoor growing. LEDs are 40–60% more efficient than HPS for the same plant output, making light choice the single highest-impact decision for long-term operating costs.

How Do LED and HPS Compare in Real Power Draw?

The wattage on a light fixture label is only part of the story. What matters is how much usable plant light (µmol/s of PAR) you get per watt of electricity consumed.

LED vs HPS power reality:

A 600W HPS system draws 600W at the bulb plus 30–50W for the magnetic ballast = 630–650W total. In a warm room, it also forces your air conditioner to work harder — generating roughly 2,000 BTU/hr of additional heat load.

A 600W LED quantum board draws 600W at the driver and produces ~30–50% more usable PAR than the HPS system. In real terms, you can achieve the same PPFD at canopy with 400–450W of high-efficiency LED as you would need 600W of HPS to deliver.

Apples-to-apples PPFD comparison:

Light Technology	Watts to Achieve 600 µmol/m²/s over 1m²	Annual kWh (18h/day)	Annual Cost at $0.15/kWh
Budget LED (1.5 µmol/J)	400W	2,628 kWh	$394
Mid-range LED (2.5 µmol/J)	240W	1,577 kWh	$237
Top-tier LED (3.2 µmol/J)	188W	1,234 kWh	$185
HPS 600W (1.7 µmol/J)	600W	3,942 kWh	$591
T5 HO (1.1 µmol/J)	545W	3,580 kWh	$537

The top-tier LED system costs $406 less per year to run than a comparable HPS system for a single 1m² canopy. Over 5 years at constant rates, that is $2,030 in savings — enough to justify significant upfront premium for quality LEDs.

How Do You Calculate kWh Costs for Your Setup?

Electricity cost calculation is straightforward:

Formula: (Watts ÷ 1,000) × Hours per day × Days per year × Cost per kWh = Annual cost ($)

Example calculations:

Setup Description	Watts	Hours/Day	Days/Year	Rate ($/kWh)	Annual Cost
Single T5 fixture (4-tube), seedlings	96W	16	365	$0.15	$84
Small LED setup (200W), leafy greens	200W	16	365	$0.15	$175
50 sq ft LED grow (400W)	400W	16	365	$0.15	$350
100 sq ft LED grow (800W)	800W	16	365	$0.15	$701
100 sq ft HPS grow (1000W)	1,000W	16	365	$0.15	$876
Small greenhouse supplement (200W LED)	200W	8	180	$0.15	$44

Don't forget ancillary loads:

Lights are typically 70–80% of total energy use in a grow room. The remainder:

Equipment	Typical Watts	Notes
Inline exhaust fan (small)	30–80W	Runs continuously
Circulation fans (2×)	20–40W	Runs continuously
Water pump (hydroponic)	5–25W	Runs on timer
Heat mat (propagation)	20–40W	Runs on thermostat
Small dehumidifier	200–400W	Runs as needed
Mini-split AC (small)	500–1,000W	Runs as needed in summer

A 50 sq ft grow room with 400W lights plus ancillary equipment typically draws 450–500W total when lights are on, and 100–150W when lights are off (fans, pumps).

What Is the Cost Per Gram or Per Head Produced?

Understanding cost per unit of output helps justify the investment and identify efficiency improvements.

Lettuce (hydroponic NFT, 50 sq ft room):

Monthly electricity cost: $30–40
Nutrient cost: $8–15/month
Packaging/miscellaneous: $5/month
Total monthly operating cost: $43–60
Monthly yield at good management: 40–60 heads
Cost per head (operating only): $0.75–1.50
Retail value per head: $2.50–4.00
Gross margin: 60–70%

Microgreens (tray-based, 50 sq ft room, 6 trays cycling):

Monthly electricity cost: $25–35
Seed cost: $15–30/month
Substrate/packaging: $10–15/month
Total monthly operating cost: $50–80
Monthly yield: 8–12 lbs
Cost per lb (operating only): $5–8
Selling price at farmers market: $20–30/lb
Gross margin: 70–80%

These figures exclude setup costs (lights, racks, systems), which are capital expenditure typically amortised over 3–5 years.

What Are the Most Effective Ways to Reduce Energy Use?

High-impact changes:

Upgrade to high-efficiency LEDs: Replacing a 600W HPS with a 300W high-efficiency LED (same PPFD output) cuts lighting electricity in half. Payback period: 12–18 months from electricity savings alone.
Dial in your photoperiod: Running lights 18 hours for crops that perform equally well at 16 hours wastes 11% of lighting energy. Use the minimum effective photoperiod for each crop.
Insulate your grow space: An insulated grow room requires less heating in winter and less cooling in summer. Rigid foam insulation on walls and ceiling pays for itself quickly in climate-controlled environments.
Use a timer-based dehumidifier: Dehumidifiers running 24/7 are often overkill. Program them to run only during the lights-on period (when transpiration is highest) or use an RH controller.
Reduce light height and increase reflection: Mylar reflective sheeting on walls increases effective PPFD by 10–30% without using more electricity. This can allow you to reduce light intensity settings proportionally.
Time-of-use electricity optimisation: In regions with time-of-use pricing, shifting your lights-on window to off-peak hours (typically 9pm–7am) can reduce effective electricity costs by 20–40%.

Lower-impact but still worthwhile:

Replace fans with EC (electronically commutated) motor fans — 30–50% more efficient than AC induction fans
Use LED strips instead of rope lighting for propagation areas
Install occupancy sensors to prevent lights staying on in unoccupied processing areas

Frequently Asked Questions

How much does it cost to run a single grow light?

A typical 200W LED grow light running 16 hours per day costs approximately $14–17 per month at $0.13–0.15/kWh. A 400W setup costs $28–35/month. To calculate your own cost: (Watts ÷ 1,000) × 16 × 30 × your electricity rate. Check your electricity bill for the rate per kWh — US averages range from $0.09 (Louisiana) to $0.28 (Hawaii), making local rate the biggest variable in the calculation.

Is solar power a viable option to offset indoor farming electricity costs?

Yes, especially for daytime grows. A 3 kW rooftop solar system generates 300–450 kWh/month in most US locations — enough to cover most small to mid-size indoor farms. The economic case strengthens in states with high electricity rates and strong solar resources. Time-of-use net metering means running lights during daylight hours maximises self-consumption. Battery storage is not yet cost-effective for most applications, but direct solar + daytime grow scheduling works well without batteries.

Do LED grow lights lose efficiency over time and cost more to run?

Yes, but gradually. Quality LED diodes (Samsung LM301H, Osram) lose approximately 3–5% output in the first 1,000 hours (initial burn-in), then degrade very slowly — typically reaching L90 (90% original output) at 30,000 hours and L70 at 50,000 hours. In practice, you would need to run a light 8 hours per day for 17 years to reach L70. The efficiency (µmol/J) remains nearly constant over the useful life of the fixture; the drop in output is more relevant than efficiency change. Budget LEDs using low-grade diodes can degrade much faster — 20–30% output loss in the first year is not uncommon with cheap panels.