a photocell connected to the sc will provide external sensor input so as to allow the sc to further fine tune the current opaqueness based upon current cloud and weather conditions sidereal information has been well known and calculable for centuries and may thus be profiled into the sc device itself weather conditions that might block the sun are random real time events although such intelligent control permits several windows to operate autonomously in a larger scale implementation it is desirable to put entire segments of building windows under a coordinated set of controls in relatively large types of environments rather than using a profile of individual windows it is possible to perform more real time data processing and to make more intelligent decisions of the opacity of every segment of a building at any point in time the sc of this invention is capable of expanding so as to operate in such a mode this system virtually eliminates all building wiring issues to put all spd windows under a central control each scalable controller is outfitted with a low power low data rate limited range radio transceiver these radio transceivers are capable of communicating on a point to point basis to one or more radio transceivers located within other scalable controllers in a 3 dimensional space around each controller the sc microprocessor is further outfitted with mesh networking software such types of software have been in existence in various incarnations for a long period of time the radio transceivers send specially formatted packets of data back and forth between each other some packets contain data which is used to operate the mesh network itself while other packets contain sensor data or window control information routing control packets.