you are better off just using the blimp as a giant
reflector (half transparent, half reflective) and
concentrating all that solar goodness onto a
'steam' turbine

would help to keep it aloft as well

solar cells weigh too much, and are too inefficient

better off treating the whole blimp as one giant
closed cycle - stay aloft indefinitely just cruisin'
on solar insolation, and pure thoughts...