Quick answer: start with 400 W of solar
A fountain pump is small but runs for hours: 75 W for 12 hours is 900 Wh a day, roughly 400 W of solar. If it only needs to run in sunshine, a solar-direct pump with no battery is simpler still; the battery is only for evening operation.
Planning result
At 200 W per module, the array target is 2 panels. That count assumes four peak-sun-hours, 75% end-to-end solar yield, 90% conversion efficiency, and a 20% planning margin. Long summer days give the most solar run time, and many water features are drained or switched off in freezing weather.
How a fountain pump actually uses power
Planning case: a submersible fountain or water-feature pump of about 75 W running 12 hours a day. Little Giant rates its small PE-1F-PW water-feature pump at 36 W; this case doubles that to cover larger fountains and taller lifts.
A fountain pump is a small motor running continuously at nearly constant power, with no thermostat or pressure switch. Its draw rises a little as the intake screen clogs or the lift, the height the outlet sits above the water, increases.
Load calculation from running watts and duty cycle
The appliance-class estimate is 75 W running for 12 h/day at a 100% duty cycle, an average of about 75 W across those hours:
Then losses and reserve raise the energy the system must collect to about 1,200 Wh/day.
Typical manufacturer nameplate/manual range for the fountain pump class, triangulated with Little Giant (Franklin Electric): PE-1F-PW water feature pump (566608) and Little Giant (Franklin Electric): Pony Pump utility and transfer pump (555112), then reduced to a conservative planning midpoint; this is not a product specification. Verify the exact unit's nameplate and manual before sizing.
A plug-in energy meter on the pump cord for a full day gives the watt-hours directly.
Solar and battery sizing table
| Design item | Planning value | Basis |
|---|---|---|
| Appliance energy | 900 Wh/day | Running W × hours × duty cycle |
| Solar collection target | 400 W | 4 peak-sun-hours, 75% yield, 20% margin |
| 200 W panel count | 2 | Rounded up; real modules must satisfy controller voltage/current limits |
| One-day battery allowance | 1,500 Wh | 90% conversion efficiency, 80% LiFePO4 usable fraction, 20% margin |
| 12.8 V LiFePO4 equivalent | 120 Ah | Nominal planning conversion |
| 25.6 V LiFePO4 equivalent | 60 Ah | Nominal planning conversion |
Evening or night operation is what needs the battery; a solar-direct pump that runs only in sunshine needs none.
Build the closest passing wiring-diagram preset
The Fountain Pump Planning System preset is an engine-passing starting point whose array, battery bank, continuous inverter rating, and surge rating each meet or exceed this page's stated planning allowances. Adjust it only from measured load data and verified equipment limits.
Inverter and startup current
Use at least 100 W continuous with 200 W surge for this planning case. A small pump starts with a modest surge, so the inverter allowance is small. Magnetic-drive pumps can hum or run hot on a modified sine wave inverter, so a pure sine wave output is the safer choice.
The 180 W startup estimate is not a substitute for the manual's locked-rotor, compressor-start, or motor-start requirements, and an inverter's surge rating usually lasts seconds, not minutes. A battery-to-inverter cable that is too long or too small can pull the DC input below the inverter's low-voltage threshold during that start even when the battery has plenty of energy, so use the diagram machine's real run length.
The common mistake
Ways to cut the load
- Choose a 12 V or solar-direct pump for features that only need to run in daylight.
- Put the pump on a timer for the hours you are actually outside.
- Clean the intake screen so the pump moves water with less effort.
- Lower the outlet: the less lift, the less power the pump needs.
What to verify before buying equipment
- The exact running watts, startup current, voltage, frequency, and required circuit from the appliance label and manual.
- Actual watt-hours over a representative day; seasonal heating or cooling loads need a design-day measurement.
- Local peak-sun-hours for the worst operating season, plus shade and array orientation.
- Controller maximum input voltage at the coldest expected temperature and maximum output current.
- Battery discharge current, series/parallel permission, terminal torque, low-temperature controls, and overcurrent protection.
- Conductor ampacity, voltage drop, terminal temperature ratings, disconnecting means, grounding, local amendments, and inspection requirements.
For a whole-system load list, use the load and appliance calculator. For the system context around this appliance, continue to the Solar water and well-pump guide.
Frequently asked questions
How much solar do I need for a fountain pump?
For the planning case on this page (a 75 W fountain pump running twelve hours a day), allow about 400 watts of solar at four peak-sun-hours per day. That covers an estimated 900 Wh daily load plus conversion, temperature, and recharge margin. A solar-direct pump with its own small panel avoids the battery and inverter entirely.
What size inverter should I use for a fountain pump?
Plan on at least 100 W continuous and 200 W surge. The start is small; for a load this size, inverter idle losses can matter more than its surge.
What battery size keeps a fountain pump running for one day?
The one-day planning allowance is about 1,500 Wh nominal usable design capacity, roughly 120 Ah at 12.8 V or 60 Ah at 25.6 V for LiFePO4. Only evening or overnight operation needs this battery.