The key of choice the load. If it`s an inductive load, use antiparallel thyristor pair (SCR-s) e.g. TIC126N up to 2A without heatsink, up to 6A with heatsink. If You want switch on-off ohmic load (heating apparat,bulbs...) use triac TIC226N. The solid state relays (SSR-s) available with SCR and triac output, depending from application, but expensive. You can build it own with triac or SCR-s and MOC3041 optocoupler..This have a LED input and optotriac output, can direct triggered SCR-s and triac.