Hmmm, "Get them out by Friday".
A bit OT, but I was surprised to learn that "Attack of the Giant Hogweed" was mostly based on fact.
With solar power, you get peak power and peak air conditioning load around the same time.
Not quite. Peak demand in California is between 6 to 7PM, peak solar production is approximately 12 noon. Peak load does not drop signficantly until well after sunset.
Something on the order of 97% of the atmosphere's mass is below 90,000'. 100km is an arbitrary value for the start of space, as the air at 100km is too thick to orbit and too thin to fly in (except dynamic soaring?). In imperial units, 100,000' seems to be the upper limit for flying and 100 miles is about the lower limit for orbiting.
The Perlan II sounds like it will handle like an unpowered U2 - where the planes ceiling will be defined by the "coffin corner" were the low speed stall (classic stall) approaches the high speed stall (Mach tuck from transonic airflow). Perhaps they will be using a more refined airfoil than the U2 to increase the Mach number for high speed stall.
IIRC, the pre-Perlan I sailplane altitude record of approx 47,000 feet was set sometime in the 1960's, surprising it took that long for someone to break that.
I first heard about use of series capacitors in an electric power systems class, 1H 1975, so they have been around for quite a while. It would seem to me that the caps should be able to withstand the DC potential set up by a Carrington event.
Any component for a high voltage transmission line is going to be gigantic. Google term "power transmission line series capacitors" should get you started.
An alternative way of minimizing the effects of a severe solar storm on the grid would be placing series capacitors on the long AC transmission lines. This is done already to increase power transfer capacity of some lines.
Since the solar flare is visible many hours before CME hits, the utilities should have time to configure the grid for the storm. The oerative word here is "should".