@HugoPT : I'm allready using arrays to upload temperature and thermostat data, but for single lightswitches, there is no need for an array, because you use only 1 lightswitch at a time, it wouldn't make sense to update 15 lightswitches statuses if you only switch 1 on or off
In an int variable you could pass 16 status of lightswitchs or anything you want.
Passing that int to emoncms is trivial and does not put to much overhead.