Can solar panels work with artificial light?
Can solar panels work with artificial light?. However, their performance and power output will never be as high as if they were exposed to sunlight. Solar panel power output will also vary depending on the type of bulb, the type of light (warm or cool), the intensity, and the wavelength of the artificial light.
Can solar panels work with artificial light?
Let’s break down some of these facts to give you a good reference of the impact of artificial light on solar energy performance. First, we need to address some technical factors.
Solar radiation and light spectrum
Solar radiation is the main source of energy used by solar panels to generate electricity. We can describe it as the transfer of energy from the Sun through a set of electromagnetic radiation that is distributed in a spectrum of light that goes from ultraviolet to infrared radiation.
The solar radiation spectrum can be divided into several regions according to the wavelengths of the electromagnetic waves that reach the Earth, as can be seen in the following figure:
Source: Geolycafe
From the figure above, we can notice that the highest irradiance values can be obtained in the visible light region. This region contains all the colors of the rainbow and includes wavelengths from 400 to 700 nm.
Based on this approach, most solar panel manufacturers focus on maximizing light absorption within the visible region. However, solar panels can also be designed to absorb light at longer wavelengths. As we can see below, some of the most common solar panel technologies, such as monocrystalline and polycrystalline modules, can cover a larger range of wavelengths, including visible light. They can also include wavelengths in the near infrared region (up to 1200nm). Other popular thin-film technologies such as CIGS and CdTe can also cover these regions, albeit less efficiently. Amorphous solar cells (a-Si), gallium arsenide (GaAs),
Source: A proposal for typical artificial light sources for the characterization of indoor photovoltaic applications, B.Minnaer and P.Veelaert, Ghent, University
As you can see, there are other wavelengths of light that can also be used by large commercially available technologies, such as silicon modules, to harness electricity. Therefore, we can ask ourselves, is it possible that solar panels can harness electricity from other light sources, such as incandescent or fluorescent light bulbs?
Artificial light
An incandescent lamp is made up of a glass globe in which a filament is heated to high temperatures (2,000 to 3,000 K) and is generally defined within a wavelength spectrum of 300-830 nm, peaking at the infrared region of light. Therefore, if solar panels can extract energy from wavelengths as low as 300nm to 1,200nm, then it stands to reason that solar panels could extract some energy from this source.
On the other hand, fluorescent lights were defined and designed to be located within the visible region of the light. There are many types of fluorescent lamps (about 12) that are designed with different technologies. However, most of them use electrically charged gases, such as mercury, to create a path for a current to flow. In turn, this will cause the phosphor to fluoresce and create visible light. This technology focuses on the lower band of the visible light spectrum that produces low ultraviolet light.
LED and metal halide technologies are also other common artificial light sources. Metal halide lamps are high pressure discharge lamps that use an electric arc in a gaseous mixture of vaporized mercury and metal halide to produce light in a broad spectrum. On the other hand, light-emitting diodes (LEDs) are solid-state lamps that use the electroluminescence of a bandgap (a barrier that limits electrons within a material) to emit light. They can be divided into cold and warm technologies.
According to a research study conducted at the University of Ghent in Belgium, we can visualize the typical wavelength ranges of all artificial light technologies scaled to 500 lux.
Spectrum irradiance versus wavelength ranges of light in different fluorescent lamps. F2: cold fluorescent lamp with a correlated color temperature (CCT) of 4230 K. F7: broadband fluorescent lamp (CCT = 6500 K). F11: three narrow band fluorescent lamp (CCT = 4000 K)
Source: A proposal for typical artificial light sources for the characterization of indoor photovoltaic applications, B.Minnaer and P.Veelaert, Ghent, University
Spectrum radiance vs. wavelength ranges of light in different LED and metal halide lamps
Solar panels tested under artificial light conditions
Ben Minnaert and Peter Veelaert from the University of Ghent asked themselves the same question that we asked ourselves. So, to find the truth, they classify all artificial lights into different categories: incandescent, fluorescent, LED, and metal halide lamps.
They then used different solar panel technologies such as monocrystalline, polycrystalline, cadmium tellurium, CIGS, and others to quantify the power outputs of these modules under indoor conditions at 500 lux (a typical measure of light intensity in square meters inside offices). ) of the aforementioned artificial light sources.
Surprisingly, they discovered that it was possible to harness electricity from artificial light through solar panels. However, the efficiency values were nowhere near what would be expected in outdoor daylight conditions.
They found that monocrystalline technology and incandescent light were the best possible combination for getting electricity from artificial light, followed by polycrystalline and CIGS technologies combined with incandescent light. However, considering an illumination of 500 lux, it was possible to obtain only 6 W/m 2 , too low for standard test conditions.
Other light sources such as fluorescents, LEDs and metal halides were not as efficient with silicon cells, but with GaAs and CdTe solar panels. However, these technologies were not suitable at all, as they could produce more than 1 W/m 2 .
Conclution
There is a lot of speculation about how solar panels work in different scenarios. For example, whether solar panels work through glass or whether they work with artificial light are among the most speculated. Based on this research, we can conclude that solar panels can work with artificial light, but the efficiency obtained by using this light source is so insignificant that it is not worth considering as an electrical supply.
Also, if we compare the irradiance spectrum of fluorescent light sources with the solar radiation spectrum, we can notice big differences.
The curve of the solar radiation spectrum follows a smooth and continuous shape that maximizes the conversion of light into electricity. We can notice that by multiplying the wavelength in nm. With the spectral irradiance in W/m 2 , we can theoretically obtain values of 1000 W/m 2 .
However, when we compare it with fluorescent, LED or metal halide spectral irradiance, we can notice that many of them have irregular peaks that do not allow smooth absorption of light. Also, these values are in mW/m2 with a 500 lux rating. When we multiply them with the wavelengths in nm, we obtain values lower than 30 W/m 2 . The difference is only astronomical.
For applications within commercial buildings related to BIPV, illuminance values may increase, however they will not be as attractive as considering installing solar panels to harness artificial light. For reference, a UEFA Champions League stadium might have an average illumination of 2,000 lux, and if you multiplied the estimated 30W/m2 at 500 lux by four (to achieve roughly 2,000 lux), you would only get around 120W/m2 values . of irradiance, which is still very low.
