Nowadays, we all are introduced to solar panels as they can easily be charged by sunlight to convert light into electricity. It is also an excellent renewable alternative to non-renewable fossil fuels. Also, solar panels are a cost-effective, efficient solution to generate electricity at a reasonable cost, even though their initial investment can be a little high.
If you are a solar power enthusiast, one common question may come to your mind: Can we use flashlights instead of sunlight on the solar panel to work?
We can use flashlights or artificial lights on solar panels to make it work. However, as we know, the number of the ejected electrons is directly proportional to the intensity of the light. So if the intensity of the flashlight is not enough, we can not generate enough electricity using the solar panel.
So, now we’ll dive into the discussion to know how solar panels work under flashlights!
How can solar panels work under flashlights?
If we want to know how solar panels work under flashlights, we must understand the photoelectric effect first.
Fundamental: Photoelectric effect
The photoelectric effect is a phenomenon that produces electricity when light or electromagnetic radiation falls on the metal or semiconductor surface. When light having particular energy falls on the metal or semiconductor surface, the charged electrons of the atoms absorb the energy of the light and get excited.
The energetic electrons go out of the Coulombic attraction of the nucleus. Then it starts to flow within the surface of the metal. These electrons are called photoelectrons. These electrons produce a current flow to the gadgets or the appliances connected to the circuit. You need to be aware that all the energy of the incident light does not produce photoelectrons as they need to overcome the attraction energy of the electron and nucleus.
This process happens in solar panels. In the case of solar panels, the surface is made up of semiconductors, mainly silicon. It has two layers, one is positive, and the other is negative. The upper surface is exposed to the flashlight, having a negative layer beneath it.
When the flashlight falls into the surface, the atoms’ bound electrons absorb the energy. These electrons flow from the negative layer to the positive one, producing the electric current. This process is known as a photovoltaic effect which is solely followed by the photoelectric effect.
Next, we will check out the solar devices which we can use under flashlights.
Which solar devices can we power under flashlights?
- LED lights of 1.8- 3.3 volt
- solar calculators, toys, and other low-power devices.
- solar charging battery bank
- PC keyboard
- solar fan, oven, and heater
Why don’t we use solar panels under flashlights at night?
1. Charging solar panels with flashlights will waste more energy
It will be a complete waste of power if we charge a solar panel with flashlights. You’ll be surprised to know the actual reason behind this. Only 20% of the total power that is incident on the panel is transformed into electrical energy. Even the most efficient solar panel could only transfer 20% or less into workable power, and 80% of the total power is wasted.
2. Solar panels are designed to work under sunlight
When the sunlight of 1370 watts per square meter incident on a panel, we can generate 150-200 watts of power from it.
Now, even if we arrange 500 watts of flashlights, only 20% of the total incident power may get transferred into electrical energy.
As you understand, we can say that we need sunlight to generate adequate energy in a solar panel, not a flashlight. You can’t expect flashlights to power your entire home. More importantly, why waste 80% of the energy if you can light up a flashlight at night?
A solar panel is quite expensive. 40 million rupees are needed To set up a solar panel of 1MW. That is, we need 40 rupees to produce 1-watt power. Also, it is noticeable that the cost of using flashlights is very high, like 2000 rupees, and you will need a good amount of artificial lights (sometimes 200-800).
On the other hand, the electricity bill will be very high to charge up those lights. So, charging a solar light with an artificial flashlight is not cost-effective.
If you assume the power consumption of artificial light is 35 watts and you use it for 50 hours, then the total power consumed will be 1750 watts-hour or 1.75 kilowatt-hours= 1.75 units of electricity. In India, you need to pay 6.15 rupees per unit. So it makes 10.76 rupees per flashlight. It seems less but now calculate it for 100 flashlights which is 100.7 rupees.
4. Not convenient for daily use
As you can see, charging solar panels with artificial lights is not convenient for daily use, especially when we have other cost-effective options to get electricity.
When do people use flashlights for solar panels?
Okay! up to now, you have understood that flashlights are not convenient for charging a solar light. But is there any way we can use solar panels under flashlights?
Probably in primary or high schools, students can use flashlights to demonstrate some experiments on the photoelectric effect.
Also, it can be used in urgent situations to convert the energy of a flashlight into a different form of energy like heat or sound energy. Charging a solar bank battery in an emergency can be a reason. Although, one needs to remember that you need a bunch of flashlights to make the solar panel work.
How many flashlights do you need for a solar panel?
Here we should decide based on which devices we are going to charge!
Solar calculators and toys
You need at least two flashlights for a solar toy of 2 watts (as 1.4 watts will be effectively used). Solar calculators are very low-power devices that operate at 2 watts and need one or two flashlights to charge up.
A solar fan has a power consumption of 18 to 20 watts. So, one will need 13 to 15 flashlights to power up one solar fan. You will be surprised to know that this energy will run up to 1 hour. If you want to use your fan for a day, you need 308 flashlights and hold them for one hour.
A solar oven operates at 1200 watts. So, you’ll need 857 flashlights to energize one solar oven with a 7-watt flashlight.
6 steps to set flashlights on your solar panel
- To charge up a solar panel with the help of several flashlights, you will need to set it up directly underneath the flashlights.
- You need to ensure that the solar panel is close to the flashlights and has an angle of 90 degrees to absorb the maximum energy.
- You would need a high-intensity bulb to make the process quick.
- Air temp is another variable that affects solar effectiveness. Incredibly high temperatures should be avoided at all times because they can harm or decrease the effectiveness of solar cells.
- Do not place the solar panel with a dark background such that it will not absorb most of the energy.
- You need to make sure that the solar panels are not dirty. The surface of the solar panel should be cleaned. You would need some water to wipe out the solar panel, and the panels will be in excellent condition.
Now you know solar panels can be charged with one or more flashlights depending on the devices. However, it is not a convenient technique to charge solar devices. You can use the previous processes in your home or lab for cloudy weather or experimental needs. But you need to ensure that you have a good amount of flashlights in your reach.