FAQ02116 of Solid-state Relays FAQ

Yes, it is.

Solid-state Relays are connected in parallel mainly to prevent open circuit failures.

Usually, only one of the Solid-state Relays is turned ON, keeping the other Solid-state Relay in the OFF state, due to the difference in output ON voltage drop between the Solid-state Relays. Therefore, do not connect two or more Solid-state Relays in parallel to drive a load exceeding the capacity of each Solid-state Relay. Otherwise, Solid-state Relays may fail to operate.

It is not possible to increase the load current by connecting the Solid-state Relays in parallel.

However, if an ON-state Solid-state Relay in operation is open, the other Solid-state Relay will turn ON when the voltage is applied, thus maintaining the switching operation of the load.