Most relays are rated for a "number of switches", usually in the few hundreds-of-thousands for both mechanical and SSDs. If you switch twice a day (on/off), you

Most relays are rated for a "number of switches", usually in the few hundreds-of-thousands for both mechanical and SSDs. If you switch twice a day (on/off), you've got a few hundred years. Note, however, that switching voltages/currents higher than rated will likely shorten the life of your relay.