Short answerA solar pump controller matches panel output to the motor, sets the start voltage and stops the pump on a full tank (float switch) or a dry well (low-water probe). Battery systems use a charge controller instead, and the pump runs from the battery.
Affiliate links on this page. We may earn a commission if you buy through them, at no extra cost to you. That doesn't change what we recommend. How we make money.
Key takeaways
- A pump controller and a battery charge controller are different products.
- MPPT pump controllers start the motor earlier and run it later in the day.
- Wire a tank float to the controller's signal input, not in series with the motor.
Safety. Panels and batteries can deliver dangerous current. Follow NEC Article 690 and local code, and use a licensed electrician or well contractor where your state requires one.
Two kinds of controller
A pump controller sits between the panels and the pump in a direct-drive system. A charge controller sits between the panels and a battery. They are different products. A PWM or MPPT battery charge controller will not, by itself, help a pump start in the morning, and a pump controller does not charge batteries.
Eco-Worthy 30A PWM charge controller
Cheapest way to charge a 12V or 24V battery from 12V-class panels. Not a pump controller.
- Type
- PWM
- System
- 12V / 24V auto
- Current
- 30 A
on eco-worthy.com, 18 October 2026
Eco-Worthy 60A MPPT charge controller
Battery charging from higher-voltage strings, with more harvest in cold and cloud than PWM.
- Type
- MPPT
- System
- 12 / 24 / 36 / 48V
- Current
- 60 A
on eco-worthy.com, 18 October 2026
Eco-Worthy 400W 12V off-grid kit
A battery-buffered 12V pumping system: panels, MPPT controller, brackets and cables in one box.
- Panels
- 4 x 100 W (Vmp 20.2V, Voc 24.5V)
- Controller
- 40A MPPT, 12V/24V, under 100V PV input
- Mounting
- Z brackets
- Battery
- Not in the base kit (optional bundles add one)
on eco-worthy.com, 18 October 2026
We have not tested these products; specifications are the merchant's own. Affiliate disclosure.
What a pump controller does
- Maximum power point tracking (MPPT) or a linear current booster trades panel voltage for current so a motor can start and turn slowly in weak light, instead of stalling until the panels reach full voltage. That can add an hour or more of pumping at each end of the day.
- Dry-run protection stops the pump when a probe or the motor's load says the well has drawn down, then retries after a delay.
- Remote switch input connects a float switch in the tank so the pump stops when the tank is full.
- Soft start and overcurrent protection reduce stress on the motor and wiring.
Float switches
Wire the tank-full float to the controller's switch input, not in series with the motor. The input carries a tiny signal current, so the float can be a light-duty switch on a long, thin cable. Check whether your controller expects a normally open or normally closed float; many pumping controllers stop the pump when the circuit closes.
For a battery system, a float in series with the pump supply is common but must be rated for the motor's starting current.
Charge controllers for battery pumping
PWM controllers are cheap and fine when the panel's nominal voltage matches the battery (12V-class panels on a 12V battery). MPPT controllers convert a higher panel voltage down to battery voltage and harvest more in cold and cloud; they let you run longer cable from the array at higher voltage with less loss. Size by the array's current at battery voltage plus 25%.
Three DC well pumps side by side on the merchant's own figures, plus panels, controllers and batteries.