[ed_denu]

Are you observing this during auto tuning? If so auto tuning will go somewhat over the set temperature as the pid is learning how quickly the oven and elements react to the on/off cycles.

If the ssr isn't cycling on and off at all once it reaches and surpasses the set temperature, then it sounds like you have something wired wrong or the ssr has malfunctioned with the contacts closed(do you have a good heat sink on the ssr?). Watch the pid when it approaches and exceeds the set temperature. The output light will be lit when the pid is calling for heat thru the elements, and off when it is not. If the output light is off and the elements are still on, then you have a wiring or ssr failure problem. Some ssr's also have an led light which lights when it is energized. Watch this also.