I think Off-Grid Storage is next... they already have that prototype working.
The truck application would take some time, IMHO, as I think they'll need to develop the chassis for it like they did for the Spree golf cart. But, they're probably a long way down that road with already having developed the golf cart chassis already.
But, don't get me wrong... I think the Off-Grid Storage market they can make for themselves, especially for extreme-weather applications, is huge. The Triad Pro eCell is tested to -50C!
Then, I think their revenues from the Off-Grid Storage products (and the golf carts already developed and moving into mass production) can be re-invested into the trucks.