Do Solar Panels Emit Light?

Solar panels can emit their own light, under the right conditions. And this light emitting ability of solar panels has one very good use.

Figure 1: Solar panel. [1]

How Solar Panels Work

The light emmiting ability of a solar panel comes down to they way in which a solar panels works in order to extract electrical energy from sunlight (The First Photovoltaic Cell). Solar panels, or rather each cell of a solar panel, are essentially diodes; an electircial component that allolws current to flow through it in one direction, but strongly resists current in the other direction. However this is not like a stop sign where the electons in the circuit wait patianely at the diode, but instead that energy must be dissipated in some way. Usually (for most computing or staddnard electrical diodes) this is in the form of heat. However, if you use the right materials, it can be dissipated as light, this is how an LED (Light Emitting Diode) works.

The Connection Between LEDs and Solar Cells

On the flip side, just how electricity pushed through an LED causes electrons to be dissipated as light (photons), photons “pushed” into an LED cause photons to be converted into electricity. This is how a solar cell works, converting sunlight into electrical energy. But just like shining a light on an LED will produce a (small) current, if you pass a current through a solar panel it will produce a small amount of light.

Why This Matters

Due to the chemistry of a solar cell, the light produced cannot be seen with the human eye as it is ultraviolet light, and it is very weak — a low dim compared to an LED, for example. As useless as this may seem, there is one good use for it: it allows manufacturers and technicians to look for faults in a solar panel. Any solar cell that has a defect or is broken won’t produce light, and so by looking at a charged solar panel with an ultraviolet camera, any dark areas show defects or cracks in the panel.

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