What happens when solar panels are exposed to sunlight but their output isn’t connected to any system?
In: Engineering
A black object that is exposed to the sun will convert very close to 100% of the light that hits it into heat. This is why black objects get very hot when they’re sitting in the sun during the summer, when the air isn’t cold enough to cool them off.
A solar panel is basically a black object that works by converting ~18% of the light that hits it into electricity instead of heat. If the solar panel isn’t connected to anything, then that ~18% of sunlight that would have been converted into electricity is instead converted into heat. At that point, your solar panel is basically indistinguishable from any other inert black object that has been left in the sun.
To be more specific, a solar panel works because the sunlight hitting the panel pushes electrons in the front of the panel through a sort of one way switch that only allows the electrons to move to the back of the panel. Once in the back of the panel, those electrons leave, pass through a transformer, and then re-enter the top of the panel. This creates a constant flow of electrons from front->back->outside the panel->back inside the panel->front->repeat.
If you disconnect the solar panel, you’re cutting the wire that leads to the transformer. Because the electrons in the back of the panel have nowhere to go, the electrons in the front of the panel can’t move to the back. Since the electrons in the front can’t move to the back, there is no movement of electrons in the panel and no current is generated. The sunlight is still being absorbed though, so it just heats the entire panel up like it would any other black object.
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