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Solar Hydroponics Calculator

Enter your hydroponic system type, grow sites, and lighting schedule — get daily kWh, solar panels needed, and cost per grow cycle.

Hydroponic system configuration
sites
W
$/kWh
Solar sizing for your hydroponic system
8 × 400W solar panels (3.2 kW system)
Pump load (24/7)50 W
Lighting load900 W
Total daily energy12.48 kWh/day
Monthly energy374.4 kWh/mo
Monthly grid cost$56.16/mo
Cost per 60-day grow cycle$112.32/cycle
Indoor vs greenhouse saving$34.02/mo with greenhouse
Est. solar system cost$9,760
Payback period14.3 yrs
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How to Use This Calculator

Select your hydroponic system type and size

Choose the system type that matches your setup — DWC, NFT, Ebb & Flow, or Drip. Each has a different pump wattage that runs 24/7. Enter the number of grow sites (plant locations) in your system. The calculator sizes lighting at one unit per 10 sites, matching a standard 4×4 grow area per light fixture.

Configure your lighting and supplemental loads

Grow lights are the dominant energy load in indoor hydroponics — often 60-80% of total consumption. Select whether you're growing indoors (full artificial lighting) or in a greenhouse (natural light with supplemental only). Then choose your photoperiod: vegetative growth requires 18 hours of light; flowering and fruiting crops trigger on 12 hours; lettuce and leafy greens thrive at 16 hours. This directly sets your daily light energy usage.

Add optional loads and read results

Air pumps oxygenate the nutrient solution and run 24/7. Water heaters maintain root zone temperature in cold climates. Once configured, the calculator shows total daily kWh, cost per 60-day grow cycle, solar panels needed, and — for off-grid setups — the battery bank size. Large off-grid systems may show a warning if the battery requirement is impractical.

The Formula

Pump Daily kWh = Pump Watts × 24 hrs ÷ 1000 Light Daily kWh = Light Watts × Photoperiod Hours ÷ 1000 Air Pump Daily kWh = Air Pump Watts × 24 hrs ÷ 1000 Water Heater Daily kWh = Heater Watts × 8 hrs ÷ 1000 Total Daily kWh = Pump + Lights + Air + Heater Monthly kWh = Total Daily kWh × 30 60-Day Cycle Cost = Total Daily kWh × 60 × Electricity Rate System Watts = Daily kWh × 1000 ÷ PSH (5.0) ÷ 0.80 efficiency Panels Needed = System Watts ÷ 400W (round up) Battery Ah (48V) = Daily kWh × 1.5 × 1000 ÷ (48V × 0.80 DoD)

Pumps and air pumps are modeled as 24/7 loads — they cannot be interrupted. Lights follow the photoperiod schedule. The water heater is estimated at 8 hours per day to maintain temperature. Solar sizing uses a national average of 5.0 peak sun hours. Off-grid battery sizing provides 1.5 days of autonomy to handle cloudy periods.

Example

Maria — Cannabis grow room, 25 DWC sites

Maria runs a 25-site DWC cannabis operation indoors with LED lighting on a 12-hour flowering photoperiod. She wants to know her energy costs and whether solar makes sense at $0.15/kWh.

SystemDWC, 25 sites
Pump50W, 24/7
Lights3 × LED 300W = 900W, 12 hrs/day
Air pump20W, 24/7
Rate$0.15/kWh

Result

Total daily kWh~12.7 kWh/day
Monthly cost~$57/mo
60-day grow cycle cost~$114/cycle
Panels needed8 × 400W panels (3.2 kW)
Annual savings with solar~$695/yr
Payback~13 years

Grow lights dominate Maria's energy bill — 900W of LED lighting accounts for over 85% of her daily consumption. Switching to a greenhouse would reduce her lighting load by 70% and cut her monthly bill significantly. For indoor-only growing, solar offsets the grid cost but has a longer payback than typical home installations due to the relatively low electricity consumption per grow cycle.

FAQ

Energy use varies enormously based on size and configuration. A small 10-site NFT herb garden with LED lights uses roughly 3-5 kWh/day. A 50-site commercial lettuce operation uses 15-25 kWh/day. A 100-site indoor grow with full lighting can use 50+ kWh/day. The biggest variable is lighting: a single 300W LED running 16 hours uses 4.8 kWh/day — more than the pumps use in a week.
Yes, but it requires careful planning. The challenge is that pumps must run 24/7 — you cannot interrupt the nutrient flow or plants will die within hours. This means you need a battery bank sized for full overnight operation regardless of solar production. For a 10 kWh/day grow operation, you'd need a 15-20 kWh battery bank and 6-8 solar panels. Smaller herb gardens (2-3 kWh/day) are more practical candidates for off-grid solar. Large commercial operations are almost always grid-tied for reliability.
Indoor hydroponics uses significantly more energy than outdoor soil growing because of artificial lighting. However, hydroponics uses 90% less water and produces yields 3-10× faster with year-round production. Compared to indoor soil growing under the same lights, hydroponics typically uses the same or slightly more energy (due to pumps) but produces higher yields per kWh. Greenhouse hydroponics is the most energy-efficient: natural light eliminates 70-80% of the lighting load while maintaining hydroponic yield advantages.
Lighting is the single biggest energy decision in indoor hydroponics. LED grow lights (300W per 4×4 area) have largely replaced T5 fluorescent and HPS for their efficiency, spectrum quality, and longevity. A 300W LED produces similar yields to a 600W HPS — cutting lighting energy in half. Over a 60-day grow cycle, switching from T5 fluorescent to LED on a 25-site operation saves approximately $20-40 in electricity costs depending on your rate. LEDs also produce less heat, reducing cooling needs.
Payback depends on system size and local electricity rates. Small home herb gardens ($30-60/month in electricity) typically have 15-20+ year paybacks on dedicated solar — the math is unfavorable unless you're expanding to a larger solar system that powers your whole home. Medium commercial operations with $200-500/month electricity bills see 8-12 year paybacks. Large commercial grows with high commercial electricity rates and significant roof space can achieve 5-7 year paybacks, especially with the 30% federal ITC and MACRS accelerated depreciation.

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