The use of those processors and ethernet were not major cost drivers.
There's a very nice technical document describing the network topology titled "A Low-Cost Fiber Optic Avionics Network for Energy Kites" in the collection of technical documents:
At this scale, no of course not. But at 100 kW or 10 kW? Remember that the argument is about applicability to other kite energy systems. Margins get very thin when power electronics costs only 0.03 USD/watt for the entire system. It gets harder to hide signal processing costs as the size of the system decreases.
System scale is a crucial component of a cost competitive energy system. I lay out the argument for this in the early part of my section - Airborne Wind Turbine Performance - of the released documentation.
A 100 kW system may prove useful to some niche, but I don't think can be competitive with the utility energy market at large, even if you give away the system for free.
At the larger scales, these electronics are not meaningful cost drivers at all.
That's true - and it was always tempting to reach for another expensive sensor when we knew that ultimately we would have to simplify and rely on simpler/cheaper components.