Renewable energy is a topic that has been making the rounds in scientific circles and communities for the last few decades. This increasing interest in alternative energy resources is a result of growing alarm about the dangers of using non-renewable energy sources like fossil fuel.
We are now living in the 21s century and we can see the undeniable proof of the harmful effects of fossil fuel resources. By increasing our greenhouse gases we have managed to increase the global temperature, which has, in turn, affected us all through increased heatwaves, flash floods, forest fires, and the like. Europe already recorded its hottest summer yet, and it is estimated to get worse. Another example of the effects of climate change would be an increase in pandemics, so if you want to avoid pandemics like the current one in the future, making the switch to renewable energy is one way forward.
Out of all of our options for renewable energy, solar energy is the most promising one yet. Of course, a lot of people still have not grasped how solar energy works, and if you happen to be confused yourself, you can keep on reading the rest of the article below:
Converting Light to Electricity
All of us already know that solar panels are used to generate solar energy, however, we do not understand how this happens. Sunlight itself is composed of photons of energy which when combined forms the rays of sunlight that reach us. If you think about it, these photons of light are traveling 9.3 million miles and take about 8.5 minutes to reach us, and there is a certain beauty in that. The amount of energy that can be generated by these photons is enough to meet the entire planet’s energy needs for a year.
Once these photons of light enter the planet and collide with the surface of a solar panel, these photons end up losing an electron each. The design and setup of the photovoltaic panel along with the general electromagnetic nature of light allows for this to happen.
This is where we talk about the electromagnetic spectrum and how it works. Essentially all of the light that we see falls under an electromagnetic spectrum. This spectrum is not just limited to light, it also includes wavelengths and energies. Different photons of light come at different wavelengths and energy levels, and this variation in wavelengths alone is responsible for creating the different colors of the rainbow.
The light that falls on these solar panels is not always effective. Certain frequencies of light are too weak and will in turn pass through the solar panel, consequentially higher wavelengths of light will end up using the extra energy to remove an electron and this extra energy will ultimately be lost.
This is where the bandgap energy comes in. This is the energy that is needed to remove an electron, and this is estimated to be 1.1 eV for silicon made semi-conductors.
You want to make sure that you have the ideal bandgap and for that, you want to make sure that you are producing enough voltage and power, which has been calculated to be at 1.4 eV for a single material made photovoltaic cell.
Solar Panel Design
We will now bring our attention to the making of solar panels or photovoltaic cells. If we break down the terms, then photo and voltaic when combined boil down to electricity that is derived from light.
A photovoltaic cell setup consists of either a single or a combination of different semiconductors in such a manner one side has a positive charge and the other has a negative charge. These cells end up creating both a high and a low potential which allows for the free flow of electrons, hence creating an electrical current.
Whenever these photons of light fall on these semiconductors, the photons get absorbed and when this happens the electrons become free and start moving along the electric field of the semiconductor which ends up creating an electric current. This is the mechanism of just a single photovoltaic cell and a single solar panel can have anywhere up to hundreds of cells. More cells create more electricity which in turn leads to more power, and this is ultimately how solar panels are set up.
Semiconductors are placed at the center of solar energy setups. Semiconductors can be made from a variety of different materials and the choice of material can affect your overall electrical output and efficiency.
The electrons are usually the charge carriers in the case of conductors like copper, however, in the case of semiconductors, both electrons and electron-holes play a part in the flow of current. By using different materials it is possible to create a situation where there is an electron surplus on one end and a scarcity in the other, creating a flow of electrical current. This is done via the process known as doping. Doping is essentially a process where impurities are purposely added to semiconductors. Different doping proportions lead to different electrical properties in the semiconductor. The two main types of doping include both P-Type and N-Type doping. N-type doping is the type of doping in which there is an electron surplus whereas P-type doping is a doping variant that leads to electron scarcity.
The Role of Silicon
Silicon is considered to be a popular choice of material for semiconductors because of its efficiency and durability. The current efficiency rate of silicon semiconductors for residential units is anywhere between 12-18% and can operate up to 23% at their best, and this is estimated to be improving annually.
Silicon isn’t entirely perfect though; silicon has a glimmering surface and this is what causes some of the rays of light to bounce back as opposed to getting absorbed by the panel. This can lead to not enough light being absorbed by the panel and affect the level of energy that is produced by the solar panel. This is where manufacturers take the extra step of using an anti-reflective coating to minimize the likelihood of the light being reflected off the surface of the panels. Another added measure taken by solar power manufacturers is to add a glass cover plate between the cells of the panel.
When activated, the semiconductor will start working on separating the electrons and making them flow from one direction to another and creating electricity in the process. This initial flow of electricity is a direct current (DC) which will be needed to be converted alternative current (AC) since the alternating current is used to run our homes and most equipment in general.
A Look at Inverters
To convert the direct current into alternating current, an inverter is used. Inverters are not just limited to converting electrical current, they also help to show important system stats like your voltage, and the current on both the DC and AC circuits, power point tracking, and overall levels of energy produced.
Types of Inverters
Inverters themselves fall into two different categories, one of them is dependent on where the inverter itself is located and the other type depends on whether an on-grid or off-grid network is being used.
When we talk about location type inverters, we will have two discuss the two subtypes as well which include the micro-inverters and the central inverters.
- Micro-inverters are the more recent of the two types of inverters and they fill in for the shortcomings of the central inverters. The invention of the micro-inverters has made it possible for solar cells to not interrupt the other’s performance.
- Central inverters have been the more commonly used choice of inverter but they do happen to have a major drawback; and that is their dependence on solar panels. So if one solar panel is not performing properly for whatever reason, then the performance of the other solar will also be affected automatically if they are connected to a central inverter.
Network-type inverters also happen to have two subtypes, namely the off-grid and on-grid network.
- Off-grid or standalone inverters, like the name suggest, are not connected to the local grid. This means that whatever energy is produced in surplus by the solar panels will end up getting stored in the batteries for later use. Of course, this means that if the panels face issues or are unable to operate properly, then the owner of the panels will not have an alternative electricity source to fall back on.
- On-grid or grid-tie inverters are connected to your local grids, and whatever energy is produced in surplus will end up going to the energy grids. Grid-tie inverters allow their owner to become eligible for actual compensation for the extra energy that is sent to the grid. So regardless of whether the panel is powering your office, home, or any other space, you are eligible for compensation. By opting for a grid-tie inverter you will continue to have access to an alternative source of electricity and also reduce your overall energy and electricity bills as well. However, if there is a power outage, you cannot regain the energy that you have already given to the grid.
While we mentioned only two categories of inverters above, there is a third type that has just been introduced in the market, and these are the hybrid inverters. This type of inverter is a combination of the other two grid-types to get the best possible results.
Hybrid inverters basically help you store any surplus energy that is produced in batteries, and if there is still some leftover, it ends up getting sent to the area grid. However, this type of inverter is more expensive.
Once the inverter has taken the direct current and converted it into alternating current, we can now power our home and appliances. The inverter takes the newly converted alternating current and then directs it towards a distribution board. This distribution board is used to separate the current into different circuits so that it can reach different parts and ends of buildings to power different types of appliances like fans, lights, the HVAC systems, etc. Fuses and circuit breakers are also placed at different points at different circuits to prevent electrical overload.
Different Semiconductor Types
We have primarily talked about silicon made semiconductors since they happen to be the most popular and well-known ones, but there are still other semiconductors that are made of different types of materials, each of which has their unique properties. These different materials include and are not limited to silicon carbide, germanium, and the recently introduced organic photovoltaics.
Each of these materials brings their own unique set of advantages and disadvantages to the table, and this can include better temperature tolerance, higher cost to lower efficiency, slower response times, etc.
We will be directing our attention mainly towards Organic Photovoltaics though. This material has garnered a lot of attention in the solar power industry since they have a lot of potentials and could potentially perform just as well as silicon at a lower price. Large-scale manufacture of this material can be profitable since can lead to the price of solar panels being lowered again, and end up encouraging more people to leap solar energy.
Organic photovoltaics are comprised of carbon-based setup that can be created in different compositions via different techniques which will in turn arm them with more unique properties. There is also the fact that organic photovoltaics are pretty flexible so that can be printed on thin rolls and can curve and bend around different materials, which further opens discussions towards adding them to fabric and clothes.
Initially, this material was rejected since its efficiency level is half of what is produced by silicon semiconductors. However, research and technological advancement has made it possible to improve organic photovoltaics’ efficiency by quite a margin and is projected to reach 25% efficiency soon.
This level of efficiency can make it possible produce electricity at as low a cost like 7 cents for every kilowatt-hour, whereas normal electricity generation can cost 10.5 cents for every kilowatt-hour, and if you stretch this across a 20-year solar panel lifespan, then you are truly saving yourself a lot of money this way.
Where Do We Stand on Advancements in Solar Technology Today?
Solar panels have come a long way when we compare them to where they started from. In the 19th century, solar panels were only believed to be 1% more efficient, so they were not even considered as potential energy sources back then. However, with the time, silicon-based solar panels were created and they managed to bring the efficiency up to 6%. The amount of progress that we have made the last 10 years alone is exponential. The efficiency of solar panels is only expected to go up to 60% in the next few years, and the incentives provided by the government like tax credit and reduced cost prices are also factors that are adding to the increase in interest in solar power and panels.
So we now understand how solar energy is generated into electricity, and how different materials and components come together to make this possible. So there is a lot of hope for the future of solar energy currently.