Solar panels are designed to work with light. That means not just sunlight but artificial light as well. But how do they work with light and different forms of light?
Light is the most important energy source on Earth. It is the primary building block from which we get a life. Without light, every single living thing from plants to animals would cease to exist.
Our main source of light is the sun. One second of light from the sun has enough energy to power the planet for 500,000 years. You could combine the output of every other major power source we have and it would only amount to a small fraction of what the sun produces.
If the sun produces that much energy from light, how does a simple lightbulb compare? Could it be possible to power your home using solar panels and light from an LED light? Not quite. Solar panels can produce light from artificial lights but nowhere near the scale of the sun. But why is this?
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Do Solar Panels Need Direct Sunlight or Just Light?
Solar panels can generate energy from all forms of light. This includes artificial light and even, to some extent, moonlight. This is because light has just about the same properties necessary to produce energy regardless of what type of light it is.
Here is an article with more in-depth insights on “Do Solar Panels Work at Night with Moonlight? “
The fundamental property necessary to produce energy from light is the presence of photons. All light contains photons. It is just a question of concentration. The stronger the light, the greater the concentration. But what are photons and what do they have to do with producing electricity in a solar panel?
The power of photons ( How do they work with solar panels ?)
Photons are the basic unit of energy in light. Solar panels are built from a semiconductor material that absorbs the photons in light and converts that into electricity. A solar panel consists of two layers. These are the positive (P-Type) and the negative (N-Type) layers.
When light is absorbed in a solar panel, photons charge the free electrons in the N-Type layer. The energized electron particles then move to fill the artificially created gaps in the P-Type layer. It is this movement that results in the flow of an electric current.
Light can be broken down into different constituents. To understand how solar panels function under light, you need to understand what light is composed of.
The light spectrum
Light occurs in a spectrum. Different spectrums of light have different wavelengths. These wavelengths have varying amounts of solar energy. A shorter wavelength has more energy than a longer wavelength. The material composition of light and its corresponding wavelength is broken down as follows.
| SPECTRUM | WAVELENGTH |
| Visible light | 380 to 700 nm |
| Infrared light | 700 nm to 1,000,000 nm |
| Ultraviolet light | 100 to 400 nm |
53% of light is infrared light. The visible light we can see with the naked eye constitutes 43% of light while ultraviolet light makes up the remaining 4%. (Source)
Most of what is converted into electricity is visible light since it has the highest intensity. Less than half of infrared is converted to energy while only a tiny fraction of ultraviolet light is turned into energy.
Artificial light sources emit light from the entire spectrum just like the sun does. The critical difference is that the sun is a massive ball of energy that emits colossal amounts of solar radiation that nothing, certainly not an ordinary lightbulb can match.
Do Solar Panels Work with Led Light?
Solar panels are engineered to work with light so they can be powered using an LED light. LEDs are one of several types of light that have been tested and used to generate an electric current in a solar panel. Other lights include incandescent, halogen, and even lasers.
Even while you can use artificial lights like LEDs to produce energy in a solar panel, they only generate a limited amount of energy compared to direct sunlight. The sun releases energy at a rate of 4.26 million metric tons per second. That is about 384.6 septillion watts. That is the equivalent of almost 2 billion of the world’s most powerful nuclear bombs. (Source)
How do LED lights compete with that? The short answer is they cannot. Nothing on Earth can. Just how much energy can you expect from an artificial light like an LED?
How Much Energy Do Solar Panels Generate from Artificial Lights?
Solar panels produce a limited amount of energy from artificial light. How much light depends mostly on the type of lightbulb and the type of solar panel.
In a study produced at a Belgian university, different lights were tested with different types of solar panels to see which combination would produce the most energy.
Incandescent lights or halogen lamps were found to produce the most energy. They improved the performance of both crystalline silicon and thin-film solar panels by a factor of 3. LED lights do not perform nearly as well with any type of solar panel, be it crystalline or thin-film. (Source)
If lightbulbs produce the same spectrum of light from the sun, why then don’t they produce the same amount of energy in a solar panel?
Why Does Artificial Light Produce Less Energy?
There are several critical differences between trying to power a solar panel from direct sunlight and artificial light.
The most important is the source and scale of energy. The sun draws its energy from the massive radioactivity within its core which is millions of times larger in magnitude than all of Earth’s nuclear power plants combined.
Compare that to a lightbulb that draws its energy from an electrical output. This is a huge energy conversion inefficiency. The lightbulb has to draw electricity to create light which is then converted back into electricity by the solar panel. Most of the energy in this conversion process is lost as heat.
Artificial lights have a much weaker spectral irradiance than the sun as well as fluctuations in the radiance which reduces a solar panel’s absorption of light
This leads to a decreased output of solar energy.
The lightbulb itself also reduces the light emittance since the light first has to pass through the glass before it reaches the solar panel.