I doubt that would be terribly relevant. The lions share of the surplus energy should be predictable based on recent grid data + 24 hour weather forecasts.
Based on nothing but wikipedia the primary methods for desalination are distillation (boiling) and membrane; neither of which sound like ramp up time would matter.
The entire internet backbone is fiber optic cables, so most data is already transferred using “beams” of light.
This is what computers do on either end of the fiber optic cables to transmit the data; except billions of times faster, using multiple “colors” (wavelengths) and similar tricks with light to stream as many 1’s & 0’s as fast as possible.