So....without knowing where to find more detail....if any one or combinations of these resources do not have enough power output - because they are intermittent resources, Apple is using battery power to replace the need?
I find it more probable that Apple has enough contractual or even installed capability to run at 100%. Having installed capability does not equate to what is available from the unit. For example, a 100MW wind farm (installed capability) rarely outputs 100MW, so to truly get 100MW at all times, you may have to install a 500MW windfarm. (assuming a 20% capacity factor) I highly doubt Apple would install up to 500MW, as this would be a ridiculously stupid idea.
Saying that you are "now running on 100% Renewable Energy" also implies that Apple is somehow managing its supply to demand via these resources in perfect harmony. HIGHLY doubtful.
Here is what is happening....the resources are pumping power into the grid. To the extent the power offsets or exceeds Apple's demand...great, they may even receive a credit from their local utility. To the extent there is no wind, sun, or low water levels, Apple is buying from the local utility.