Solar power is a very popular energy source in many countries. As it is free renewable energy many tend to use solar energy instead of grid power. Not just that as the electricity generation process using solar is very clean it helps us to protect our environment.
Solar energy is very popular among travelers more than domestic users because it makes them easier to travel for days and even deeper into rural areas without worrying about finding grid power to power up their gears. Even though using solar energy is advantageous solar users also face many difficulties.
One of them is that the intensity of sunlight we received is not always constant. It changes drastically throughout the day. Not just that but there can be days that there is no sunlight at all. Also if you are using portable solar-powered equipment during travels sometimes you may forget to charge them during the daytime and at night you may suddenly realize that your device has zero percent charging left. In such instances, it will be useful if you can charge them with artificial lights.
Yes, you can charge solar cells with artificial light. But this is not as efficient as the use of direct sunlight to charge the solar cell. Because of the limited energy supplied by the artificial light, this method can only be used to charge equipment like calculators, torches, etc.
How do solar panels use light to charge cells?
Solar panels are made of different semiconducting materials which able to absorb sunlight energy and convert it into electricity. When sunlight hits the solar panels the energy will be absorbed into the panels and this causes an increase of energy inside the atoms of the panels. This incident will result in free atomic electrons by ionization events. Released free electrons will combine and form an electron flow across the panel. This electron flow generates a flow of positive electricity in opposite direction.
This current flow is DC. As the cell requires DC supply you can charge cells directly without worrying about any other complex conversions. Even though the cells need DC supply most household items require AC supply. So in this case you have to convert DC supply to AC. This can be done using an inverter. Refer to our article about how does solar energy work to produce electricity if you want to know more.
By converting DC supply to AC you can operate all the items you need without any problem.
How we can use artificial light instead of sunlight?
The reason behind this is very simple. As we all know sunlight contains a spectrum of electromagnetic radiations. Sunlight is made up of the following electromagnetic radiation types;
- Visible light
(The amount of electricity produced when using the wave range of visible light is higher than the other two.)
Artificial lights such as incandescent light which contains electromagnetic radiations with nearly the same wavelength as sunlight can supply energy to charge solar cells without much problem.
Mostly used artificial lights for this purpose is;
- Incandescent bulbs
- Fluorescent bulbs
- LED bulbs
These two types of light have mostly the same wavelength range as sunlight. So they can charge solar panels. But charging solar panels using artificial light is not efficient as sunlight. Let’s talk about the reasons for that later in this article.
Use of incandescent light bulbs;
The incandescent light bulb is simply a filament with a glass envelope/covering. The light will be generated by heating of the filament. Compared to the other artificial light sources incandescent bulbs generates high light output. Also in contrast to the other artificial light sources, the incandescent bulb has a continuous spectrum of light with a wide range of wavelengths. That means that this spectrum is more dynamic and has more visible colors and very similar to the sunlight so incandescent bulbs able to supply energy to the solar panels. But incandescent bulbs use more energy at energy conversion. So this is not profitable as free sunlight.
Use of fluorescent light bulbs;
These light bulbs are glass tubes filled with gasses and mercury vapor. Electrons in the gasses emit the photons at UV frequencies by the reactions that happen between gasses and mercury vapor. These UV frequency photons are then will be converted to light photons by the phosphor coating inside the glass tube. Spectrum is limited and not dynamic and continuous as the spectrum of the incandescent bulb so this is not much effective as incandescent light bulbs.
Use of LED bulbs;
Even though LED bulbs use less energy than incandescent bulbs (less than 75%), LED s are not effective in supplying enough energy to solar panels. The reason for this is LED has narrow spectra when compared to incandescent light bulbs. So it will take more time and more LED bulbs to get the same outcome as incandescent bulbs or sunlight.
Why ultraviolet and infrared is not much suitable to charge solar cells?
Solar panels can absorb a portion of ultraviolet energy at the far end of the spectrum of sunlight. But you cannot use the whole portion of UV energy in the sunlight spectrum. As UV rays have more energy even though it tends to work efficiently at first it produces more extra energy which will be converted to heat inside the solar system. This elevates the internal temperature of the solar system. These elevated heat levels can damage the internal components of the solar system such as solar cells, inverters, etc.
If we have a look at the infrared rays we can clearly say infrared rays do not have enough energy to release the atomic electrons properly. So it will be very hard to produce electricity with infrared rays.
How to use artificial light to supply energy to your panels?
To get the energy needed for solar panels it is better if you can place the panels closer to the light bulb. When there is more distance to travels light photons tend to scatter. Unlike sunlight, there is not much amount of light photons supplied from the artificial light bulbs. So the loss of light photons due to scattering will lengthen the time you have to spend to charge the solar cells.
Why artificial lights are less effective than sunlight when supplying energy to the solar panels?
As we described earlier in this article solar panels work from the energy supplied by the light photons of the sunlight. In the case of artificial light, they are only designed to light up spaces not to supply energy for any conversion processes.
Also as we know light bulbs like incandescent light bulbs use a lot of energy to the conversion processes happening inside the light bulb. One of the aims of using solar energy is to minimize the use of grid power and save your money. But if you are trying to get the required energy from artificial light you need grid power or power from house solar to power up the light bulbs. So the purpose of using solar energy won’t be achieved. But in emergency cases like charging your solar-powered traveling torch or lamp, you can always use this method.
As we told earlier light bulbs are not designed to supply energy for solar panels. So it has many barriers like a glass envelope which will cut off part of the energy. So you cannot get 100% of the energy.
Also unlike LED bulbs, the light of incandescent and fluorescent light bulbs are not directed in one direction. It gives a scattered light beam. So the solar panels will not get all the light photons emitted from the light bulbs.
Can you use light from solar light to charge its cell?
The answer to this question is debatable. For most solar lights they use LED bulbs. Theoretically, they say that LED bulbs get 0% from supplied energy for energy conversion processes. But this is not 100% correct. LED bulbs use around less than 15% of energy. Not just that but there are many conversion losses throughout this whole solar light system. So we cannot get the total energy supplied to the solar light as the outcome. So using the light of the solar light to charge its cell is not much effective and practical.
As you can see you can use artificial lights to get the energy to charge solar cells. But this is not much effective as using sunlight. As we described earlier artificial lights are not designed to supply energy. So they have barriers that absorb or reflect the output light photons.
Also, some of the artificial light use lots of energy to work. So they need lots of grid power or power generated from house solar which will fail your initial target of using solar panels and saving money. Also, some bulbs have very narrowed spectra unlike sunlight so they are not capable of providing enough amounts of photons. You cannot produce lots of energy by this method.
So you cannot use this method to work equipment which requires more energy. But you can always use artificial lights to charge simple devices such as portable solar torches, lamps, and calculators. Anyway using artificial light to replace sunlight is not a better option at all. This is only good for emergency purposes only.
Do solar panels work in the moonlight?
As you know the moonlight is a reflector of sunlight. So it also has photons but it is down by a factor of about 1/350. Because of the limitations of the technology available today, even though the solar panel absorbs this energy it is not enough to generate a direct current inside your solar panel.