The event will also give the public a chance to learn more about solar rebates for their homes and businesses.
"This annual event is a way to reach out to people, to show them the possibilities of a city powered by a sustainable source - the sun," said RPU General manager David Wright.
Leading solar vendors Mohr Power Solar, Solar Max, HelioPower and Martifer Solar will all have booths at Solar Day.
Children and their parents will be encouraged to create "solar art" and take home a solar pizza box oven.
Solar Day runs from 10 a.m. to 2 p.m. Saturday at the Riverside Plaza, 3545 Central Avenue in Riverside.