There is a great deal of radiation all around us, all the time, and it would be great if we could harness and use all of it. Solar panels can take in the sun’s light, but can they take in more than that? There is a great deal of energy all around us, and if we could harness it, we could solve a lot of problems.
No, solar panels cannot absorb gamma rays. Gamma rays have the shortest wavelength on the electromagnetic spectrum. Solar panels cannot absorb light wavelength of less than 10 nm. Gamma ray wavelengths are much shorter than that.
Gamma radiation can’t be absorbed by solar panels, nor can it create superheroes, but it does bring up an excellent question, about what we can do with radiation, and about what powers solar panels.
Electromagnetic Spectrum
The electromagnetic spectrum is the spectrum on which we’ve placed the different types of radiation we see and experience in the world around us. It is measured by energy, frequency, and wavelength
Gamma rays are high in energy, and high in frequency, while being low in wavelength. Radio waves are exactly the opposite.
The section we generally consider to be “light” lies between ultraviolet and infrared. This is the target for solar panels.
We explain radiation by looking at it on this spectrum, and it’s no wonder gamma rays are an attractive option for a source of energy–we don’t use them for much. Radio waves are useful for communication; most people use microwaves in their home on a regular basis; the light spectrum dominates our lives as everything we see with our eyes is from the light spectrum; and X-rays help us in medicine, imaging fractured bones and helping doctors.
Gamma rays are used as a sort of industrial x-ray, used to image welds and metal joints to look for flaws, but that’s a far cry from creating super-humans and providing an infinite energy source.
How do solar panels work?
In order to understand why gamma rays can’t be absorbed by solar panels we have to first understand how those solar panels work–how they convert light into electricity.
Common solar panels function by placing layers of silicon on either side of a conductive field, mostly comprised of metal and metal wiring. The layers of silicon are divided into positive and negative sides by manipulating the number of electrons within the layer of silicon. The side with fewer electrons has a positive charge.
This array is then placed in direct sunlight, and the particles that make up that sunlight, photons of light, travel into the solar panel. Photons collide with electrons, and the electrons are pulled to the positive end of solar panel. The electrons continue to move, and electricity is produced.
These explanations can be overwhelming, and hard to understand, so I’ve linked a video that explains the system in simple terms. This presentation is focused on the application of solar, but the first half explains solar panels simply, with visuals to help.
This explanation doesn’t address why gamma rays, or any other type of radiation don’t function the same way–after all, they’re all made up of particles, so why can’t all of them collide with the electrons in the panel?
The answer is that the components that make up solar panels aren’t compatible with other types of radiation. Specifically looking at gamma rays, their frequency is too great for any reasonable consistency of collision. The gamma rays pass through the solar panel.
What do solar panels absorb?
After addressing why solar panels can’t absorb gamma rays, the question then becomes, what can they absorb?
The majority of the energy produced by solar panels is produced by the visible light spectrum–red to violet. With the use of silicon these light particles remain at the optimal energy level, frequency, and wavelength to dislodge electrons and create an electric current.
Infrared light lacks the energy required to knock electrons out of their place in the bond. While some ultraviolet light will be utilized by the solar panel, its frequency is greater than the optimal threshold for solar power.
With the limited spectrum of radiation used by solar panels, it’s easy to wonder why we use silicon rather than some other element. Silicon is the second most abundant element on the earth’s crust, making it an easy choice. Silicon is also only a semi-conductor of electricity, so it insulates the solar panels as well as powering them.
Could we ever absorb gamma rays?
It is important to analyze where gamma rays found on earth come from before addressing the use of a solar cell to create electricity.
Gamma rays are created in very specific, usually high heat situations. Our sun does not release gamma rays with any sort of consistency. Outside of here on earth, the release of gamma rays is reserved for neutron stars, supernovas, and the like. Here on earth they come from lightning strikes, nuclear explosions, and radioactive decay.
This makes the use of a solar panel type generator less effective, as they require near constant input of solar energy to function in any useful capacity whatsoever. So, without a source of endless gamma rays, it just isn’t practical to try to modify a solar panel to a sort of “gamma panel”. The gamma rays would also inevitably break down whatever panel is designed because the radiation will cause decay.
So, solar panels aren’t really an option, but there are devices designed to collect gamma rays and turn them into energy. The radioisotope thermoelectric generator is used in proximity of radioactive isotopes to collect the gamma rays, and then convert them into heat.
Solar panels can serve very effectively in producing electricity for mankind, but for now and the foreseeable future, they are limited with the types of radiation that can be converted into electricity. Gamma rays are not the future of solar, though they do have a place in energy production in our world.