The light can be operated a few different ways. The first would be a switch in the house or garage. Another more effective way is to have the switch operated by a photo cell so it turns on when it goes dark and turns off at dawn. Using a LED light with a color index of 2700K will mean that you only change the bulb once every 25 years. Hope this helps.

Is the copula accessible from within the space for bulb changing?

Yes as the LVL ridge beam goes through the space and given that it is storage it was not a critical area