In a typical solar powered security light, the solar panel charges a battery. When the sun is out, is the battery capable of absorbing energy at the rate the panel generates it ? Or does the panel have over capacity relative to how fast the battery can charge?
The specific situation that comes to mind involves two security lights, each with its detachable solar panel. if the sun shines on the panels differently during the day (due to the shade of trees etc.) it might make sense to modify the wiring so each panel charges both lights. If one panel has over capacity relative to charging a single light, it could charge both of them when it was in the sun and the other panel was shaded.