Every bit of solar energy must hit the battery bank on a solar electric vehicle to make it viable. Few other places require such size and weight efficiency.
If we are to get the rated 305 watts of each solar panel we must use the a controller in the 90% plus range of efficiency. The solar panels must be arranged for maximum power in a parallel configuration. Right now the panels are wired in series and any shading of any panel takes the power down to almost zero. If the panels were wired in parallel each panel would feed the battery bank independently -regardless of the shaded panel.
We must also take advantage of the MPPT or the maximum power point tracking function of modern charge controllers. MPPT keeps the panel electronically producing all the power it is capable of producing give about 30% more solar harvest per day. This alone would put the bus at a one day full charge advantage. However, an MPPT controller does not yet exist for this situation.