How Many Solar Panels to Run a Well Pump? (Calculator + Examples)
A well pump uses 0.5-6 kWh per day depending on well depth, pump type, and household water consumption. You need 1-4 standard 400W solar panels to power it at 5 peak sun hours -- making well pumps one of the more practical appliances to run on solar, especially for off-grid properties.
Quick answer
A 400W solar panel produces about 1.66 kWh per day at 5 peak sun hours (400W x 5h x 0.83 derate). The number of panels depends on your well depth and daily water needs:
| Well Type | Daily kWh | 4 PSH (Cloudy) | 5 PSH (Average) | 6 PSH (Sunny) |
|---|---|---|---|---|
| Shallow jet pump (under 25 ft) | 0.5-1 kWh | 1 panel | 1 panel | 1 panel |
| Mid-depth submersible (25-150 ft) | 1-3 kWh | 1-3 panels | 1-2 panels | 1-2 panels |
| Deep submersible (150-400 ft) | 3-6 kWh | 3-5 panels | 2-4 panels | 2-3 panels |
Formula: panels = daily kWh / (panel watts x PSH x 0.83 derate), rounded up.
Well pump energy breakdown
Well pump energy consumption depends on three main factors: well depth (how far the pump lifts water), flow rate (gallons per minute), and total daily usage (gallons per day). A typical household of four uses 200-400 gallons per day.
| Specification | Shallow Jet Pump | Submersible (1/2 HP) | Submersible (1 HP) |
|---|---|---|---|
| Well depth | Under 25 ft | 25-150 ft | 150-400 ft |
| Wattage | 250-500W | 500-1,000W | 1,000-2,000W |
| Run time per day | 1-2 hours | 1.5-2.5 hours | 1.5-3 hours |
| Duty cycle | 100% (while running) | 100% (while running) | 100% (while running) |
| Daily energy use | 0.25-1 kWh | 0.75-2.5 kWh | 1.5-6 kWh |
| Monthly energy use | 8-30 kWh | 23-75 kWh | 45-180 kWh |
| Yearly energy use | 91-365 kWh | 274-913 kWh | 548-2,190 kWh |
Well pumps do not run continuously. A pressure switch activates the pump when tank pressure drops below a set point (typically 30-40 PSI) and shuts it off when pressure reaches the upper limit (50-60 PSI). The actual daily run time depends on your water consumption patterns and pressure tank size.
Try the calculator
Adjust the panel wattage and your location's peak sun hours to see exact production numbers for your setup.
Benchmarks: U.S. avg 4.98 · Phoenix 6.54 (highest) · Seattle 3.95 · Anchorage 3.17 (lowest). Above ~5.5 = sunny · 4.5–5.5 = average · below 4.5 = cloudy.
Tap to see sensitivity analysisSensitivity analysis
| Scenario | Value |
|---|---|
| Low (-20%) | 1.3 kWh |
| Expected | 1.6 kWh |
| High (+20%) | 1.9 kWh |
Your daily production scales linearly with both panel wattage and peak sun hours. A 10% change in either input changes your result by 10%.
Running it off-grid
Well pumps are one of the most common solar-powered appliances on off-grid homesteads. There are two main approaches:
Option 1: Solar-direct with water storage (recommended) Instead of storing energy in batteries, store water in a tank. A solar pump controller connects your panels directly to the pump, running it whenever sufficient sunlight is available. Water flows into an elevated storage tank (or pressurized tank), and gravity or a small booster pump delivers water to the house.
- No battery needed -- the water tank is your storage
- Typical setup: 2-4 panels, a pump controller ($200-$400), and a 500-1,500 gallon storage tank
- Tank should hold 2-3 days of household water needs for cloudy-day buffer
Option 2: Battery-based system If you need water on demand regardless of sunlight:
- Daily consumption: 2 kWh (typical mid-depth well)
- Autonomy target: 2 days
- Total energy needed: 2 x 2 = 4 kWh
- At 12V with lithium (LiFePO4) batteries at 80% depth: 4 kWh / 12V / 0.80 = 417 Ah
- At 48V: 104 Ah
Inverter sizing: Well pump motors have a significant startup surge of 3-7 times the running wattage. A 1 HP submersible pump drawing 1,000W at steady state may surge to 3,000-7,000W at startup. Size your inverter accordingly -- a 3,000-5,000W pure sine wave inverter handles most residential well pumps. Alternatively, a soft-start device ($50-$100) reduces surge current by 50-70%.
See our battery charging calculator for exact sizing.
Running it grid-tied
For homes already connected to the grid, adding solar panels to offset your well pump is straightforward and cost-effective.
Most well pumps cycle throughout the day, drawing short bursts of power as the pressure tank depletes. In a grid-tied system with net metering, your solar panels produce a steady stream of energy during daylight hours. When the pump is off, excess production flows to the grid. When the pump kicks on, it draws from both solar and grid as needed. Your net metering credits balance out over each billing cycle.
A mid-depth well pump using 2 kWh per day needs just 2 panels producing a combined 3.32 kWh at 5 PSH. That 66% surplus provides comfortable headroom for seasonal variation and accounts for the fact that well pump usage tends to increase in summer (lawn watering, garden irrigation) when solar production also peaks.
One important consideration: if you rely on a well pump for your household water supply, a grid-tied system alone leaves you without water during power outages. Consider adding a small battery backup or a manual hand pump as an emergency backup.
Energy-saving tips for well pumps
Reducing your well pump's energy needs means fewer panels and lower costs:
- Install a larger pressure tank. A bigger tank (40-80 gallon) means the pump cycles less frequently, reducing wear and total energy consumption. Each pump startup draws the most energy.
- Fix leaks promptly. Even a small dripping faucet can cause the pump to cycle hundreds of extra times per month. A running toilet can waste 200+ gallons per day.
- Use water-efficient fixtures. Low-flow showerheads and faucet aerators reduce total water consumption by 25-50%, directly cutting pump run time.
- Irrigate during sunny hours. If you water a garden or lawn, schedule irrigation during peak solar production (10 AM to 3 PM) to maximize direct solar offset.
- Consider a constant-pressure pump. These variable-speed pumps adjust motor speed to match demand rather than cycling on and off. They use less energy per gallon delivered, similar to how variable-speed pool pumps save energy.
- Check your pressure switch settings. A narrower pressure range (e.g., 40-60 PSI instead of 30-50 PSI) reduces the volume pumped per cycle but increases cycle frequency. Find the balance that minimizes total energy use for your household pattern.