It seems to me, that it is assumed, that one will have direct sun for the entire work day? As well, unless it actually is sunny and you moved the truck or the panels once very hour to keep the sun in a direct line and the panels at the best angle for the time of year, then you would still need a big solar panel array. Then what happens when a cloud goes by or a tree shades the panels or the panels are not moved and the angle changes from direct, to an ever more increasing side angle and loss of production? What happens is, you quickly lose solar electricity generation. To solve this, and as others have suggested, you would need a really big battery bank (which could also be expensive depending on the size and the safety requirements and the monitoring or automation / generator or grid switching?). If batteries are considered, where are you going to put all the batteries and their accompanying weight? Can your vehicle handle the extra weight of batteries, never mind solar panels and frames? And how do you charge that big battery in time for the next day and at what cost, not just for the electricity from the grid, but for the cables, charger and accessories to do that. For big power needs, it is very difficult to beat the low cost of grid power and the portability of propane or diesel.
As other posts have discussed, it's winter for us in North America. I've had many cloudy days in a row and my panels often only produce 5%, yes 5 percent of their capacity, so I've had to run the generator now and then to recharge the batteries. On a brighter say high overcast day, with the panels facing due south at the correct angle, I still on some days only get 10-20% of their power producing potential. So I don't run my energy intensive appliances, even with my $2,000 CDN DIY battery as a backup, cause it's going to be cloudy again for the next 2-5 days and possibly to cold to auto start the diesel generator.
Solar means SUN, it does not include clouds, shade, early morning or late afternoons, as part of it's power production. Creating heating and cooling with electricity is extremely energy intensive and so expensive. Most people that I know, all who are grid connected, are not aware of this and that solar requires sunshine, constant sunshine ..... or one heck of a lot of panels to compensate for the measly 5-10% produced when clouds roll in or the sun is blocked by a tree or a building as it crosses the sky and shades the panels, drastically reducing solar generated electricity production.
Hopefully, you have an ideal location for direct sun and the patience to learn and then constantly monitor the constant watts out vs watts in.
