1. The idea
Pumping water takes energy. If the pump runs during sunny hours, that energy comes straight from the panels and the battery is kept for the house. The pumped water goes into a tank, which acts as the night reserve: the system's «water battery».
2. What you need
- Growatt SPF 6000 ES PLUS inverter with CEG 51.2 V battery. Growatt inverters
- Contactor with motor protection breaker: starts the pump and protects it.
- RCBO 30 mA type A, sized for the pump.
- Float switch or pressure switch: submersible pumps usually use a float.
- Timer, so the pump only runs during sunny hours.
- Water tank.
3. How it works
When the tank level drops, the float (or pressure switch) asks for water. If it is daytime, the timer lets the command through and the contactor starts the pump. When the tank is full, the float cuts the command and the pump stops.
4. Pump starting current
When starting, a motor draws 3 to 5 times its normal current. The Growatt handles twice its rated power for 5 seconds (manual, page 39): so the pump must be chosen considering the starting current, not only the power on its label.
5. Protection and cables
Protection devices and cables are sized on the power of the pump actually installed. There is no one-size-fits-all: the electrician chooses them for the real pump.
6. The detailed wiring diagram
The block diagram helps you understand how it works. The detailed wiring diagram, with terminals and connections, is reserved for those who bought through Carmine Energia Gratis: write to Carmine with your CEG pre-order number. Wiring and testing must be done by a qualified electrician.
7. Frequently asked questions
Float switch or pressure switch?
For a submersible pump filling a tank, a float switch is usually used. A pressure switch is used when the pump has to keep pressure in a water system. The CEG diagram works with both.
Can the Growatt start the pump?
The Growatt handles twice its rated power for 5 seconds. A pump draws 3 to 5 times its current when starting: check it for the pump you want to use, before buying it.
Can the pump run at night?
It can, but the energy then comes from the battery. The CEG diagram uses the timer precisely to run the pump on sunshine and use the tank as the night reserve.
What cable size do I need?
It depends on the pump power and the cable length to the well. The electrician decides it for the installed pump.
Talk to Carmine
Before choosing components and connections, let us check your system together.