Question

How do some producers and consumers each rely on light from the sun

Answer 1

if the sun does not shine then the grass and other plants (or producers) cannot grow, if the grass cannot grow, food does not exist for the primary consumers such as grass hoppers, which means the frogs have nothing to eat, and the foxes have nothing to eat and so on so forth.
The consumers rely on the producers and producers rely on the sun, without one or the other a food chain does not work.