in solar cell there is depletion region formation happen due to p-n junction & a kind of electric field is generated & this field cause the separation of electron hole pair which are induced due to photo electric field. so at the end of p & n material there become more concertation of charge carrier & when connected with load the flow of charge carrier occurs & production of electricity happen.

but during the measurement of solar cell voltage what we consider ? 1) is it the only voltage that is developed due the depletion region's electric field or 2) there is consideration of electric field that is developed due to concentrated charge carrier at the end of p & n material or 3) something else you want to highlight.