Your System Parameters
Total gallons your farm needs per day
gallons/day
How many consecutive cloudy days you want to cover
days
Installed cost per 1,000 gallons (poly tank typical)
$/1,000 gal
Per kWh for LiFePO4 batteries (includes BMS)
$/kWh
Rated power of your solar pump motor
kW
Hours needed to pump your daily volume
hours/day
Cost Comparison
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Water Tank Total Cost
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Battery Bank Total Cost
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Tank Volume Needed
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Battery Capacity Needed

Water Storage

Upfront Cost--
Lifespan20-30 years
Annual MaintenanceNear zero
DegradationNone
Space Required--
20-Year Cost--

Battery Storage

Upfront Cost--
Lifespan10-15 years (LiFePO4)
Annual Maintenance$50-100 (monitoring)
Degradation2-3% per year
Space RequiredSmall (indoor)
20-Year Cost--

Recommended Option

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Water Tank Advantages

  • 3-5x cheaper per day of autonomy
  • No degradation over time
  • Provides fire protection reserve
  • Emergency water supply for drought
  • Can gravity-feed for zero energy use
  • Simple technology, no electronics to fail

Battery Advantages

  • Pressurized water on demand 24/7
  • No large footprint on farm
  • Can power other farm equipment
  • Works with existing pressurized systems
  • No freezing risk in cold climates
  • Instant switchover, no manual valves

Water Tank Disadvantages

  • Requires large physical space
  • Freezing risk in cold climates
  • Algae growth if not covered
  • Gravity feed may need elevation
  • Not suitable for pressurized drip

Battery Disadvantages

  • 3-5x more expensive upfront
  • Capacity degrades over time
  • Requires replacement in 10-15 years
  • Temperature sensitive
  • BMS failure risk

Hybrid Approach: Best of Both Worlds

Many farms use a small water tank (1-2 days of autonomy) combined with a small battery (for nighttime pressure). This provides redundancy at a fraction of the cost of full battery backup. The tank covers multi-day cloudy periods, while the battery ensures pressurized irrigation at night.