Can a solar panel be used as a Light Dependent Resistor?
It's not the resistance that varies much with light, so no, I wouldn't use the panel that way.

However, the short circuit current is pretty linear with light, so you could make a circuit that detected light that way.  One way to do this is to use a opamp in transimpedance configuration.  It turns a current into a voltage while keeping the input voltage nearly fixed.