A solar pump without storage only pumps while the sun powers it. To water at night you must store either energy in a battery or water in a tank, and the two cover different needs, so choose by schedule, not by habit.
What Is the Night Pumping Problem?
The night pumping problem, and what battery storage and tank storage each mean.
Why Does Night Pumping Matter?
Crops and livestock need water on their schedule, not only in sun hours; the daily-output article shows sizing must start from daily volume, and the livestock article shows tank storage decouples the solar day from the watering schedule.
When Should You Decide?
Decide at design time, before choosing an inverter type or a tank size; revisit it when night demand grows or a herd grows.
Where Does Night Pumping Apply?
Irrigation blocks on a night schedule, and livestock watering where animals drink around the clock.
How to Choose Between Battery and Tank Storage
- Work out the night demand volume in cubic metres.
- Tank route: size the tank for night demand plus a cloudy-day buffer; the livestock article advises at least two to three days of demand for herds.
- Battery route: size the battery from night energy in kWh (power times hours), and avoid the Ah trap from the battery-capacity article — compare in kWh, not Ah alone.
- Check the inverter type: a sun-driven solar pump inverter does not run a pump from a battery at night; night battery pumping needs a hybrid inverter with battery support.
- Weigh complexity: a tank is simple, with no electronics to maintain; a battery adds cost, upkeep and eventual replacement.
- Decide by schedule: a fixed night schedule usually favours a tank; variable demand with no room for a large tank favours a battery.
Battery vs Tank
| Option | What it stores | Covers | Limits |
|---|---|---|---|
| Tank | Water | Night demand plus a cloudy-day buffer | Needs space and working pressure |
| Battery | Energy | Night pumping on any schedule | Cost, upkeep, replacement, kWh sizing |
Decision Guide
| Situation | Lean to |
|---|---|
| Livestock, steady daily demand | Tank, two to three days of reserve |
| Irrigation on a fixed night schedule | Tank |
| No room for a large tank, variable demand | Battery plus a hybrid inverter |
Related Reading
- Can a solar inverter work without a battery?
- Hybrid inverter battery capacity: kWh vs Ah
- How to calculate daily water output for a solar pump
- Solar pump inverter for livestock watering
- QB100-PV solar pump inverter
Frequently Asked Questions
Can a solar pump run at night without anything added?
No: with no sun and no storage, there is nothing to power the pump.
Is a battery always better than a tank?
No: for steady demand a tank is simpler and cheaper; a battery fits variable schedules.
How big a tank for livestock overnight?
Size for at least two to three days of demand, as the livestock article advises.
If I add a battery, will my solar pump inverter run the pump at night?
Not by itself: a sun-driven solar pump inverter needs sun; night battery pumping needs a hybrid inverter with battery support, so check the inverter type first.
Does a bigger tank mean I can use a smaller pump?
No: the tank covers timing, but the pump and array must still deliver peak daily demand inside the sun window.
Send your night demand volume and watering schedule for a storage check.