like your idea and I'm waiting for updates. Thought about participating in the 2017 race, too, but girlfriend has little motivation and it would take almost all of my 2017 holiday days.
Good thing there was no big race in 2017, but the announcement for the 2018 race is the bomb - 12000km from Lyon to Canton!
I have been building and trying new things (sorry for not updating anything for a long time here)
I still haven't build solar panels nor tested the individual cells I have. For one because I have not found the glues that satisfy my requirements. I was told the solar encapsulants that are available would not adhere well to polycarbonate, and a special silicon I fond that is made for bonding polycarbonate can supposedly not do surfaces without ventilation, so I am still considering the option to buy ready made panels which are probably made with EVA sheets. Since I need better finances anyway to be able to participate I created a Patreon presence: https://www.patreon.com/SunTripToGo
and I am considering to try a crowd funding campaign too!
I am in communication with the Sun Trip organizers and try to build on the current fat bike prototype within the limits of their race rules (max. 1100Wh 48V battery max 45 km/h support, max 2m^2 Exposed Solar Array etc)
Lets look at the last two prototypes: