With my friend we built a solar powered glider (4m wingspan). Yesterday we made a 7 hours flight with 7800mah battery pack, the total load was 17500mah with solar cells.
It was great BUT, during the day the controler was fighting with thermals to regulate the altitude, what a waste of energy !
I tried to set the maximum sink to zero in TECS params but it didn't work. I'm sure there is a solution to let the plane taking altitude with thermals. The max climb max is set to 0,5m/s and it works great to limit the power and it is enought to lock the alti.
Maybe someone know how to let the plane free to climb but managing an altitude floor.