They don't need to work with solar for now. It will be awhile before they have produced enough to drag down utilities. But in the future, they will need to make the EESU chargeable from DC and not just AC, which will be simpler and easier, so that it can just be plugged into any DC solar system. Solar companies will be interested enough and efficient enough that Zenn and EEStor will not have to worry much about it. They will not have to do anything except listen when solar companies make requests about what voltage and hook ups to use. One thing i failed to mention is that maybe utilities can easily handle the extra load if the charging is done at night.
Charging at night ought to be the norm for commuters, so long as the EV has reasonable range. My commute is 23 miles one-way, 46 miles round-trip. If Zenn's cars have a 75 or 100 mile range, they ought to be fine for the vast majority of commuters, with no need to re-charge while parked at the office.
Overnight charging at home really fits nicely with the off-peak hours for electric utilities and one hopes that they will set up preferential pricing to make it even more attractive for all us commuters to switch to EVs.
My other hard requirement is the need to be able to stay up with 55 to 65 mph traffic. No way am I going to buy a car that only goes 35 or 45 mph. Being able to support these higher speeds with reasonable range requires quite a bit more stored energy, which is where the EEstor value prop starts to kick in. Let's hope those guys in Texas are the real deal !!!!