S440 optimiser

SolarEdge S440 is a module-level power optimiser for compatible residential SolarEdge inverters. Installations after 1 April 2024 have higher permitted input-power and short-circuit-current limits under the same S440 name.

S440 limits after April 2024

For installations after 1 April 2024, the permitted input power is 490 W and short-circuit current is 15 A. Earlier installations remain subject to their original limits.

That condition should remain attached to the installation date. It is not evidence that every older S440 installation can be redesigned to the later limits, nor does it change the module’s voltage window.

Module open-circuit voltage, operating voltage and short-circuit current must all fit the applicable S440 schedule. Wattage alone is not a compatibility check.

S440 strings and SolarEdge inverters

S440 performs MPPT at the connected module and sends its output into a compatible SolarEdge optimiser string. Minimum and maximum optimiser counts vary by inverter family, as does the connected power permitted on a string.

The exact S440 part number and applicable dated row must be used with the inverter’s design table. A connector or enclosure match does not replace that electrical check.

New installations must not mix S-series and P-series optimisers in one string.

S440 SafeDC and operating status

The low shutdown-output value applies when the optimiser is disconnected from an operating compatible inverter. SafeDC is a supported-system behaviour, not a replacement for isolation, proving dead and safe working procedures.

The August 2025 policy covers eligible power optimisers subject to its terms. S440 remains in the current residential S-series schedule.

Related entries

• SolarEdge
• S500 optimiser
• S500B optimiser
• Power optimiser
• String design voltage windows