I've been trying to wrap my head around some of the economics of building out DCFC stations. Something I learned recently is that the Tesla Superchargers aren't actually large, high-power modules but rather a number of low-power (10 kW) modules chained in series.
In terms of economy, are there advantages to the smaller module model? For instance, if I wanted to build a 100 kW DCFC tower, would it be cheaper to use ten 10 kW modules or four 25 kW modules? Would there be additional costs or complications?
I'm not sure if there's an inherent advantage to the smaller modules on a clean sheet. I think they all use very similar high power transistors to manage the power, so I'd suspect the cost would scale fairly consistently.
Tesla derives two advantages from the modular approach for their specific case.
First, the modules they use in the Superchargers are the same as the onboard chargers they install in every car, so they presumably get big economy of scale cost benefits since they are building hundreds of thousands of them per year now.
The second benefit is granularity in charging. The electronics are connected to a pair of stalls, and by having 12 discrete modules, it has the ability to connect some to one outlet and some to the other, letting it max out the first car to plug in and give everything that's left to the second car, so they get twice as many plugs for a given input power and almost the same investment cost. Charging is slower for the second half of the cars if the first group of cars are low on charge, but it's much better than being left waiting for the other session to finish.