Square D brand like traditional AC pump pressure switches, with solar MC4 connectors to wire inline on the positive (+) wire of your solar array to cut off power when your system gets up to desired cut-off pressure. Set to 20/30 psi by default but adjustable.
To create pressure shutoff system with a storage tanks you’ll need a mechanical float valve. For an irrigation system you'll need valves that toggle zones on and off. Both when closed will spike pressure in the line between the pump and the valve. If somewhere along the line between the two you have this tee and pressure switch, you can cut power from your solar panels to your pump.
Let us know if you have questions but they are really easy to install and wire!
Other Common Pressure System Parts
Mechanical Float Valve