[nuriaion]

I think that would actually be more expensive as you still have the all the hard problems. Like how do you isolate the power electronics. You can use air which is cheap but needs a lot of space. (i learned that you need 1mm per 1kV) You need a lot of space which has to be very secure. etc

Additionally you need to control 5000 converters without getting oscillations etc. (probably over glas) Also they will probably need a lot more space.

[londons_explore]

At very high voltages, I would expect the whole lot to be sealed in a polymer resin for life. 1 million volts through epoxy resin requires a spacing of just 1 inch (call it two inches for a safety margin). Then your whole converter station can be the size of a shed, and the whole project can fit within existing space on existing utility land.

[entropicgravity]

Voltage is just a potential, like gravity. Even at thousands of volts you would still need just 5 volts to operate equipment in the usual way. Communicating between large voltages can be done with fibre optic (i'm guessing) or wifi.

[scrlk]

How would you deal with the heat generated by the power electronics if everything is sealed in polymer resin?

[bmicraft]

Built in water cooling channels?

[londons_explore]

At these voltages, water is way too conductive.

You can use pumped oil though.