There are several ways to do this. An obvious (hopefully) way is to incorporate that sensitivity into your logic, so that your logic isn’t triggered/activities run when the weather criteria are not met (solor energy below threshold).
Another way is to use a separate group to enable/disable your irrigation control group. You can enable/disable a group within a sensor by using a Device Action activity on the ReactorSensor itself, and choosing the
SetGroupEnabled action to either enable or disable the irrigation condition group as appropriate.
The former is probably more desirable, as doing the latter opens the possibility that clouds could move in while irrigation is running, so it’s possible to disable the irrigation group while it’s active and thus it can’t shut it off until the cloud cover clears and the group is re-enabled. A simple solution is to make sure that the activity that disables the irrigation group also ensures that the irrigation is forced off.