I have a 6.6 kW solar and 2 PowerWalls from Tesla. During sunny periods when temperatures are mild, I can actually get some of the energy to charge my car, but most of the time the solar doesn't even offset my house's power consumption, let alone the car.
An example of a high quality solar panel is the ones that Tesla sells. They are 340W peak output with a 97.5% efficient inverter. They are 5.7 ft long and 3.3 ft wide. They would probably fit in the Clarity if you put the back seat down, but I haven't physically tried fitting them.
Back of the envelope calculations, you'd probably need about 8-10 of those on an average day (i.e., if you aren't at the equator at noon on a cloudless day with the panels exactly angled to maximize insolation). They might fit in the car, but they are going to weigh about 300 lbs. The car can handle the weight if you have 1-2 passengers and no other cargo.
Assuming you design or can find a custom inverter that directly converts the DC of solar panels to 240V AC, current state of the art devices of this sort would take up the front seat of the vehicle, or you might get lucky and be able to fit one in the foot well of the back seat.
So if you had a Clarity, $8000-10000 of solar panels and a $2000 piece of high-density power electronics, you could conceivably unload these solar panels, set them up in your average North American locale with less-than-ideal sunlight and less-than-ideal orientation of the panels, and get enough amps at 240V to mostly keep the car charging during the day. Setting this up would probably take at least 20 minutes, probably closer to an hour unless you had help; would occupy a surface area on the ground comparable to the footprint of a house; and would be completely useless if there were any nearby object casting a shadow (a building, a tree line, etc.) unless you somehow bring a bunch of heavy metal struts with you to put the panels up above the shadow (strap them to the roof of the Clarity maybe?)
Suffice to say, this is not a suitable or sustainable solution for most commuters. If you assume an ideal case -- you are at the equator at noon with no clouds -- that cuts down the number of panels you'd need to about 3 of these 340W panels. They'd still weigh almost 100 lbs, take up most of your cargo volume, and require a hefty inverter.
These sizes and weights do not really describe a "portable" setup, but the purpose of this thought experiment was to demonstrate that it probably is just barely possible to do this with current technology. But the realities of our lives probably prevent this from being something you'd actually want to do, even if you had the money to buy the equipment, just due to the size and weight of the panels.
Solar is pretty ideally suited to rooftops. In many parts of the world you can minimize your usage of the dirtiest power generators on the grid by installing rooftop solar. That's because the baseload often has a combination of renewables (e.g. hydro) and nuclear, while peak power demand is often satisfied by coal or liquid petrolem (e.g. diesel or oil) power plants. This will allow you to recharge your Clarity while knowing that your kilowatt-hours are not having a large carbon footprint. If you really want to maximize how clean your power is, set your EVSE to charge late at night, when usage is at its lowest. People are asleep, so the usage is low.
The idea of having the ability to power your car from the sun "on the go" is extremely attractive, and trust me, I'd love it if we could do that. But for the time being, to charge your Clarity with renewables you need to plug into an EVSE at a facility or house that has a fixed installation of some kind of renewable energy (usually solar, but wind, hydro and geothermal are also possible).
If you find yourself running out of EV range and consuming a lot of gasoline, the Clarity is probably not the ideal vehicle for you. You could get a BMW i3 Rexx, an EV, or keep an eye out for new PHEVs in the future with a bigger battery. Or try to get some kind of EV charging (even if it's just from the grid) at the various places you go, to minimize the amount of gasoline miles.
Good luck!