Solar panels are already quite familiar devices in the US. These are components that can convert sunlight into electricity and that are made up of solar PV cells, which are manufactured by using semiconductor materials like silicon. When sunlight hits a solar cell, it knocks electrons loose from their atoms and then these electrons flow through the cell, creating an electric current. This is the basic principle that applies to all solar panels.
In addition to this principle, solar panels have also been designed to work using the visible spectrum of light from solar energy radiation. The visible spectrum of light is defined according to the wavelength of the light and can be found between 400 and 700 nm. However, it has been found that some solar panel technologies, like monocrystalline and polycrystalline ones, can use wider wavelengths that can cover part of the ultraviolet spectrum and part of the infrared wavelengths as well. In other words, they can also generate electricity from artificial light, such as fluorescent lights and incandescent bulbs.
However, not everything is as good as it sounds. Artificial light is nowhere as good as sunlight to generate power from solar panels. This is because artificial light does not contain as much energy as sunlight. As a result, when a solar panel is exposed to artificial light, the output ratings will be much lower. In a few words, solar panels and artificial light are not a good combination.
How Good is Artificial Light When Compared to Sunlight?
To put some numbers in perspective, the solar irradiance (power per unit area received from solar radiation) at the Earth’s atmosphere level can reach up to 1,360 W/m2. If we evaluate the irradiance reaching a location in the Equator at noon and on a clear day, then the average irradiance will be 1,000W/m2.
These are actually the values that are taken for reference in laboratory test conditions for solar panels, typically known as Standard Test Conditions (STC). But, even these values are not that representative of real-world conditions in most locations across the globe. This is why solar panel manufacturers began implementing reference values for Normal Operating Cell Temperature (NOCT) conditions, which are measured at 800W/m2, and that are more likely to be found on a clear sky sunny day during summer.
Now, when evaluating the performance of artificial light we can think of an average office environment that typically has fluorescent or LED kind of lights and that has an average illuminance of 500 luxes. A study from Ghent University in Belgium found that a typical fluorescent or LED type of light, which is now typically found in most offices and households, can generate equivalent values of less than 10 W/m2. As can be imagined, they are worlds apart.
What Are The Best Artificial Light Sources For Solar Power Generation?
The performance output under artificial light conditions varies depending on the type of light and the type of solar panel. The best possible combination will be using a monocrystalline solar panel and incandescent light, typically known today as Edison light bulbs. These refer to the real heat tungsten/carbon filament light bulbs, not LED Edison-style light bulbs that can be seen in many solar string lights nowadays. The reason is that incandescent light has a smooth spectral irradiance curve with good irradiance values and that the monocrystalline cell has a wide wavelength absorption and efficiency. However, as we know, the industry has been shifting from these incandescent light sources because they are not energy efficient.
The second best choice is to combine modern light sources such as LEDs, metal halide lights, or a typical broadband fluorescent lamp, with Cadmium-Telluride (Cd-Te), Gallium-Arsenide (Ga-As), Amorphous (a-Si), or even Copper-Indium Gallium Selenide (CIGS) solar panels.
Artificial Light and Solar Power Applications
Despite these limitations, there are some potential applications for solar panels in artificial light environments. For example, solar panels can be used to power small devices, such as calculators and watches, in indoor environments.
If you were wondering whether or not your solar panel could work inside your house using artificial light, now you know that the answer is yes. However, while solar panels can have an electrical output when receiving artificial light, they are not a good source of energy to generate electricity from solar panels. The differences between generating solar power outdoors and indoors are simply astronomical, which is why using solar cells to generate electricity indoors is only practical for very small electronic devices or science projects.