How Solar Energy Systems Work: Understanding the Basics
If you went back in time and told someone that one day people would be making electricity from the light of the sun, they might have taken you to the local witch-doctor to cast out whatever spirit was possessing you. Go back far enough, and people would have locked you up in an asylum and thrown away the key for merely trying to explain what electricity is! With the progress of technology, the line between magic and science has become more and more blurry, if you think of it in those terms. Just look around yourself right now, and count out a few things that a caveman would have sworn, on the bones of his ancestors, were magic. I’m guessing there are too many to count. From your computer screen, to your car, from your air conditioner or fan, fridge, or microwave to your Roomba, everything would appear to be magical to a caveman or cavewoman. So, what separates science from magic? For instance, I could shout “Abracadabra!” every time I turn on my light, but other than annoy my cat, that wouldn’t change the fact that the light would still turn on after I flip the switch. Is magic just unexplained science? Or maybe a better way to look at it is that science is explained magic. Either way, we’ve found the difference between science and magic. Science can be explained, quantified and repeated. Magic, not necessarily so. The point of taking you down this trip to looney town is to hopefully coax you into reading on and understanding how solar energy works. Afterall, if we can’t explain our science better than that witch-doctor could explain his (or her) concoctions, we might as well all start making “confused unga bunga noises” every time we switch on a light. Another, more grounded reason is that if you’re planning to spend upwards of $4000 on a system, you might want to know how it works. This way not only can you equip yourself with the knowledge to make the most financially sound decisions, but you also develop acumen that can guard you against some shady characters who would gladly take your money and do a mediocre job. So, buckle up, and join us on this journey to understand how solar power works!
Solar Power 101: The Fundamentals
The sun is our planet’s single largest source of energy. One hour of sunlight alone is enough to provide the entire world with enough energy for a year. Trying to harness this unlimited, for all intents and purposes, power is only a logical step in the evolution of our energy industry. Since Edison invented the first lightbulb (no offense to the Tesla fan club, please put down those coils!) and since Michael Faraday discovered electromagnetic induction, human beings have always been seeking out newer and more potent ways to exploit the world’s resources and use them to power bigger cities and larger factories. So much so, that we’ve pushed our planet almost to the point of no return, for us anyway. Make no mistake that if humanity collectively drowns in a climatic disaster of our own making, the earth, and life on it, will go on like it has for eons. But who wants that, right? So, the onus is on us to now find cleaner and more environmentally sustainable ways to coexist with the planet and its wonderful biodiversity, and in doing so, secure a better and brighter future for our children and their children.
Enter Solar Energy. Solar energy is the brave new frontier in our quest for energy sustainability. Not only is it 100% clean and renewable, it is practically free (unless the government decides to tax sunlight!). Solar energy is seeing global adoption. The world’ largest economies like China, the United States, Japa, Germany, India, the United Kingdom and Australia are among the top adopters of solar energy. Advancements in solar energy systems has made this possible, as solar power is now cheaper and more efficient than ever. In this series of articles, we’re going to go through the basics of solar radiation, photovoltaic and concentrating solar-thermal power technologies, electric grid systems integration and the costs of solar energy. Finally, we’ll also look at what’s new in the solar world and how research and development in China and the U.S is driving innovation in the aforementioned areas. For the remainder of this article, we’re going to look at how solar energy systems convert sunlight to electricity, in the simplest manner possible.
What Exactly is Solar Power?
Simply explained, solar power is the process of converting the sun’s light into useful forms of energy. The sun’s light is called solar radiation or electromagnetic radiation. Every part of the earth’s surface receives at least some solar radiation over the course of a solar year. The amount varies from place to place and from time to time. Not all places receive the same amount of solar radiation. What solar technologies do, is that they capture this radiation and convert it into electricity.
How Do Solar Energy Systems Work?
Solar energy systems work in the following steps:
1) Solar Panels Activate by Exposure to Sunlight
Solar panels are made up of smaller cells, which are made of silicon, a metal frame and a glass casing all encapsulated in a special film. Then of course, there is the wiring, which connects the panel(s) to the rest of the house. The cells in a solar panel are made up of silicon because silicon (the second most common material on the earth’s surface) has a symmetrical crystal lattice that makes converting light into electricity much easier than any other material. Silicon made solar cells provide the most efficient, cheapest and longest lasting cells in the world. These cells absorb sunlight during daylight hours. You will normally see solar panels grouped together in arrays, or ordered numbers to maximise the surface area exposed to the sun, and they will often be placed on roofs or another outdoor area. Solar cells are often referred to as Photovoltaic Cells.
2) Solar Cells Produce Electric Current
Solar cells have two layers of silicon that act as a semiconductor within them. This is often referred to as the wafer. The top layer has a positive charge and the lower one has a negative charge. This creates an electric charge in the solar cells. When light strikes the surface of the cell, it energises the crystal lattice and allows photons (the energy particles that make up solar radiation or light) to knock electrons free from atoms and generate a flow of electricity within the wafer. This creates an electrical current within the solar cell.
3) Solar Inverters Convert DC to AC
In the previous step, we saw how solar energy is converted into electrical energy within the solar panel. Through wires, this energy can be transmitted to a socket. However, the electrical current generated in this manner is called direct current (DC). In direct current, electrons flow in one direction. This is dangerous, as victims who get shocked with DC are unable to pull their hands back, as the electrons all flow continuously, without break and in one direction. AC, or alternating current, allows electrons to periodically change their flow. Every so often, the electrons will reverse direction. AC is much safer to use (RIP Topsy the Elephant!) because it allows people to pull away from the source of the current when electrons change direction. That’s what a solar inverter is for. They convert DC to AC.
4) Converted AC now Powers Your Home
The newly converted AC now reaches all the panels in your house through wires and is ready to be used by any appliances plugged in. It works exactly the same way as grid power, but the source of the power is the sun, harnessed through solar panels installed on your roof. Houses can remain connected to their local power companies and draw electricity from both their solar panels as well as the national grid to supplement shortages in solar power.
5) The Net Meter Measures Energy Usage
When you’re not at home, your solar energy system is still collecting energy (unless you stay home during the day and are out at night). This excess energy is supplied to the grid and your local energy provider will provide credits for the amount of energy you send back to the grid. This is called a feed-in tariff. The net meter monitors the amount of incoming and outgoing energy from your solar power systems.
How Solar Energy Systems Work: Understanding the Basics (Part 2)
Welcome to part two of our series on understanding how solar energy systems work. If you haven’t already, do check out part one, which covers the basics of how solar energy systems like solar panels work.
In this part, we’re going to cover the essentials of sunlight (or solar radiation, if you speak nerd). Solar radiation is what we refer to as sunlight. Other words are electromagnetic radiation and solar resource, if you really want to go full nerd. Solar radiation is can be captured and transformed into more useful and usable forms of energy, like heat and electricity. In the previous article, we briefly touched upon how solar panels can do this. Solar panels are one of the best technologies available to us at this time that can efficiently and safely make solar radiation usable. However, despite the fact that sunlight is ubiquitous, the scalability, usability and availability of these technologies still very much depends on the availability of the solar resource. What this means is that there will always be some areas more fruitful for large scale solar-power production than others, depending on factors like climate, atmospheric conditions, precipitation, temperature and cloud cover.
Another key concept to keep in mind as we proceed into this section is solar irradiance. Solar irradiance refers to the power per unit area received from the sun, in the form of electromagnet radiation. The unit for measuring solar irradiance is watt per square metre.
Basic Principles Affecting Solar Resource Availability
There is no part of the earth’s surface that does not receive at least some sunlight (talk about stating the obvious!), but that does not mean that sunlight distribution is uniform. In fact, it varies from place to place, and this variation depends on the following factors:
- Shape of the earth
- Geographic location
- Time of day
- Local topography
- Local climate
- Local weather
Based on these factors, solar energy systems can produce energy after harvesting solar radiation.
Since the earth is round (sorry flat-earthers, it actually is round and Australia exists!) the sun strikes the surface at different angles. The equator gets the most energy, since the sun is directly 90 degrees overhead throughout the year. The farther we move from the equator, the more the light strikes the surface at a slanted angle. This is most pronounced on the poles, where the sun light strikes at a steeply slanted angle. The more slanted the sun’s rays are as they enter the atmosphere, the more of the earth’s atmosphere they have to traverse through to reach the ground. This means that the rays become scattered and diffused because of the effects of the earth’s dense atmosphere. Another factor to take into account is the 23.5° tilt of the earth’s axis of rotation. The tilt ensures that the polar regions cannot receive any sunlight at all for part of the year. So, installing solar energy systems in this part of the world may not be the best idea, as even in peak summer, the sun’s rays do not have as much potency as they would in Australia or Africa.
Furthermore, since the earth’s orbit is elliptical, the northern hemisphere experiences the summer season during June and July, as it is both tilted towards the sun and also because the earth’s orbit is closer to the sun. Summer solstice falls on June 21 for this very reason. Therefore, in the countries of the north, solar energy systems will be at peak efficiency at this time. In the northern hemisphere, we see days begin to extend from the spring (vernal) equinox to the fall (autumnal) equinox. Down south in topsy-turvy land, June and July is when we experience winter. Though the earth is closer to the sun, the southern hemisphere is tilted away from it. This means less solar radiation and reduced capacity of all solar energy systems down south. The southern hemisphere receives its summer months in December and January, making them peak months for solar energy systems to do their business.
Another factor to take into consideration is the rotation of the earth. It affects the position of the sun in the sky, and thus we see hourly variations in sunlight. In the mornings and evenings, the sun appears low in the sky, and so its light has to travel farther through the atmosphere. Meanwhile in the afternoons, the sun is directly overhead and at its highest point. The light has to travel its shortest distance and the amount of solar radiation that reaches the surface peaks at this time. This is when solar energy systems are at their most efficient.
Direct vs. Diffused Solar Radiation
As we said earlier, the sunlight that travels through the atmosphere is diffused and scattered by the atmosphere. Not only is the earth’s atmosphere very dense (hence making life on the blue planet possible) it is also filled with other particles like dust and pollution. These factors can all deflect and diffuse sunlight and reduce the effectiveness of solar energy systems. The factors responsible for this include:
- Air molecules
- Water vapor
- Cloud cover
- Dust particles
- Pollutants, like smoke or smog
- Forest fires
- Volcanic ash
Solar radiation that reaches the earth after having been diffused because of these particles is called diffuse solar radiation. If solar radiation is not diffused, (this can happen in hot and dry climates – though air molecules and the ozone layer will always diffuse some solar radiation, the level of diffusion can drastically vary based on the aforementioned factors) then it is referred to as direct beam radiation or just direct solar radiation. The sum of the solar radiation, including both the direct and diffuse radiations is called global solar radiation. At best, solar radiation is reduced by 10% on clear and dry days, and by 100% on thick and cloudy days. As you may have guessed, these conditions can adversely affect the output of solar energy systems.
Measuring Solar Distribution
Solar radiation is measured by scientists throughout the year at different locations and at different times. The scientists then estimate the amount of sunlight falling on regions at the same latitude with identical climates. Measurements of solar radiation are typically measured on either a horizontal surface, or on a surface tracking the sun.
Solar radiation data for solar energy systems, particularly photovoltaic systems, is measured in kilowatt-hours per square metre (kWh/m2), while direct estimates of solar energy are expressed as watts per square metre (W/m2). Solar distribution in Australia is ample for photovoltaic systems to be extensively used, given that they make use of both direct, as well as scattered light. Nonetheless, output can be expected to increase and decrease with seasonal changes as mentioned above. But with its sunny disposition, Australia is well placed to take advantage of advances in solar energy systems. So much so, that the Australian governments have had little to no difficulty in meeting the renewable energy targets set by the federal governments. Many states have, in fact, hit and exceeded the targets well before the deadline. Though places like Tasmania have a harder time than others keeping up with solar energy systems adoption, it is still very much a viable option. As far as Australia is concerned, photovoltaic is the most efficient and hence widely adopted solar energy system. Even so, the amount of energy such a system would generate depends largely on the site location and day to day condition of the atmosphere. A higher average of available sunlight hours is usually a good indicator of how effective a solar energy system will be in a given area. To find out about the viability of PV systems across Australia, be sure to read our articles on each area, and also on the services Integra Solar provides in each of these locations.
In the next article, we will delve into the basics of photovoltaic systems, including photovoltaic technology, basics on PV cells their design and efficiency. Remember, in order to make the most of their solar energy systems, customers must remain abreast of the latest developments in the solar industry. However, they must also be well versed in the basics, so that some shady corporation or dealer cannot just pull the wool over their eyes. To that end, we always recommend going for reputable and trusted solar panel companies like Integra Solar. Not only do we partner with the best in the business, but our service record speaks for itself. For all of you solar PV needs, look no further than Integra Solar.
How Solar Energy Systems Work: Understanding the Basics Part 3
Welcome to part three of our series exploring the basics of how solar energy systems work. In this lesson, we will be covering the basics of solar PV systems and understanding their basic operations. We are going to take a more detailed look at solar energy systems in this particle than we did in the first part of this series. The goal here is to understand the ways in which these systems operate, their basic functions and limitations. Please note, however, that this is not a completely detailed guide on how solar energy systems operate, but more of a ‘primer’ series of articles that is intended to bring new and potential customers up to speed on how solar energy systems operate. In the future, we may do a more in-depth guide on these systems so do come back periodically and see what’s new. So, without further delay, let’s get to the article. Welcome to solar PV systems, 101.
What is Solar PV Technology and How Does it Work?
PV (Photovoltaic) systems are the most widely used and universally accepted solar energy systems in the world. Solar PV systems convert sunlight into a usable for of energy, which we call electricity. A PV cell is often referred to as a solar cell. It usually contains 1 or 2 watts of power generation capacity. Solar PV cells are usually made up of semiconductor materials, usually no thicker than four human hairs. A semiconductor is basically a material that allows electricity to be conducted through it better than an insulator can, though not as effectively as a conductor. Hence the ‘semi’ in the name. Now, you might be wondering, well then, why not just use conductors in solar energy systems? Why use semi-conductors in the first place, since they conduct energy better to begin with? The answer to that is in something called the ‘band gap’.
The principle on which PV cells work is called the photo cell effect. As we explained earlier, sunlight strikes the surface of the solar cell and bumps free an electron from the atoms of the cell. A valence band is basically the outermost electron orbital, which allows electrons to jump from it to the conduction band. The conduction band comprises of the inner orbitals of the atom, and usually have the lowest unoccupied electron states. The gap between the valence band (the place from where the electron will jump) to the conduction band (the place the electron will jump to) is called the band gap. Insulators have a large band gap, semiconductors have a small band gap, and conductors have no band gap to speak of. As the size of the band gap increases, more energy is needed for electrons to jump from the valence band to the conduction band. Insulators have a large valence band, meaning they need a lot of energy for electrons to become excited and make the jump, while semiconductors need far less energy to achieve this. Conductors have electrons running amok like rabbits in breeding season, and don’t even get me started on superconductors! But this still doesn’t answer the question, why not just use conductors? They always have free electrons jumping about, why not just use them? Well, that’s because moving electrons does not automatically translate into a current. Free electrons flowing in one direction means a current. In a conductor, the electrons move randomly and not in a particular direction. With a semiconductor, electrons can be bumped and made to flow in a controlled manner. There’s more science to it, but we don’t want to overload you with information at this stage.
Now that we understand the basics of semiconductors and why they are used in solar energy systems, let’s get back to solar panels. Since solar cells produce only a small amount of energy, they need to be strung together in the form of panels, and panels are attached to each other in the rectangular shapes we’ve all seen. These ‘grids’ of solar panels are called arrays. Arrays can then be connected to the grid, and they usually are because you want to take advantage of those lovely feed-in tariffs, and that’s how solar panels are made! They are encased in glass or plastic, or a combination of the two, in order to help them withstand the outdoors. A solar PV system can be tailored to meet almost any energy requirement, subservient only to geographical limitations.
But PV modules are only a part of a solar energy system. Sure, they may be the main part, but there are other equally essential systems, without which solar panels would just be very expensive parking sheds or roof tiles. These other components include mounting systems and structurers, inverters and meters.
Mounting Structures for Solar Energy Systems
PV arrays are mounted on durable structures called mounts. These mounts are designed to keep the panels facing sunwards and to withstand the elements, including hail, sleet, rain, snow and corrosion over the course of decades. The angle and face of the solar panel depends on the mounts. Your solar provider will inform you of the best angle to tilt your panels based on latitude, the orientation of your property and your energy requirements. Integra Solar’s specialists will do this all for you and help you make the best decisions based on these and other factors.
Currently the most popular mounting method is the rack mounting method. It is robust, versatile, easy to construct and simple to install. However, more cost-efficient and more sophisticated mounting methods are constantly being developed. Stay tuned to Integra Solar to keep abreast of all the latest developments in the solar world.
Some of the more sophisticated mounts are tracking mounts. These are best used for solar energy systems mounted on the ground. The mounts track the sun throughout the day and keep the panel facing sunward for maximum energy absorption. There are two types of tracking mounts:
- Two-dimensional tracking mounts
- Three-dimensional tracking mounts
Two dimensional mounts track the sun from east to west, while three dimensional mounts ensure that they face the sun at all times throughout the day. Needless to say, more sophisticated mounts with moving parts cost more and also need more maintenance. Ultimately, it is for each consumer to decide whether they want to pay extra for the performance. However, as systems become cheaper, moving mounts are becoming more and more affordable.
Inverters and Storage Systems
Inverters convert DC current from the solar energy system into AC current for use. A system will have a single inverter or many, depending on its size and output. One inverter is easier to use and maintain, while microinverters attached to individual panels can be more expensive and cumbersome to maintain, yet they allow for the individual operation of each solar panel. This is useful if some modules are shaded, for example. Inverters will, on average, have to be replaces at least once during the lifecycle of your solar energy system.
More advanced inverters called smart inverters allow for two-way communication between the system and the electricity grid, helping balance demand and supply automatically. This reduce cost, enhance grid stability as well as reduce the chances of grid malfunction, remote as they may be.
But if you’re not into sending your (not so) hard earned solar energy back into the grid and you want to use it later, then purchasing a battery system is in order. Batteries can store electricity harvested from your solar energy system for later use. This practice is becoming more and more common with time, as battery systems become cheaper and more accessible. Furthermore, battery systems help reduce the overall strain on the national grid, and in the long term, wide-scale use of storage technology can not only help reduce the cost of electricity for individuals, but can also reduce dependence on the electricity grid.
This concludes our article on the basics of solar PV setups. In the next article, we will go over the soft costs of using solar energy. We all are aware of the costs associated with installing and maintaining a solar panel, but there are certain other costs that are incurred while operating and establishing solar energy systems. These include costs paid by solar providers like Integra Solar to reach and find new clients, pay suppliers and cover the bottom-line. For rooftop solar energy systems (PV), soft costs represent the single largest share of total costs. In the interest of transparency, we will go over these in the next article.
How Solar Energy Systems Work (Part 4)
Welcome back to our fourth article on how solar energy systems work, where we go over the basics of how PV systems operate, their potential as well as limitations. In this part, we are going to cover the basics of soft costs. What are soft costs? Who pays for them? How much of these costs is passed onto the customer? What do these costs entail for the longevity of the solar PV industry? These and many more questions will be answered below.
Why You Should Care About Soft Costs
Soft costs are non-hardware related costs associated with the use of solar technology. If you’re going solar, you already know that you’ll have to pay for a lot of hardware (depending on the size of your system, of course). This hardware will include solar panels, solar inverters, mounts and maybe even storage systems. Soft costs are aside from this. They include financing, getting permits, installing the system on the customer’s end and acquiring new customers, paying suppliers and making up for overhead costs on the solar company’s end. As you may have guessed, a part of these costs will be passed onto the customer, and they represent a significant and growing portion of the costs associated with solar energy systems. The prices of solar energy systems are constantly on the decline. This is inevitable as technology develops and solar energy systems see widespread adoption. However, soft costs represent a growing portion of the costs borne by suppliers and customer when switching to or supplying a solar PV system. There is a plethora of factors contributing to the growth of soft costs, and so pinpointing their source can prove difficult. A variety of solutions are therefore needed, when addressing these costs.
Soft costs can be broken down into the following main ones, though mind you, there are likely to be more and their significance may vary from state to state and country to country. Nonetheless, the following list should give you an idea of the main soft costs associated with your solar energy system. They are listed in order of least importance. Generally, a company’s administrative costs will always be higher than a government sales tax. So, this list should give you a rough idea of the costs from least to most expensive.
- Sales Taxes. On average, this represents 3% of the total cost.
- Permits and inspections. On average, this represents 8% of the total cost.
- Supply chain costs. On average, this represents 8 % of the total cost.
- Installation costs. On average, this represents 10% of the total cost.
- Sales, marketing and customer acquisition. On average, this represents 16% of the total cost.
- Overhead costs (profit and administrative costs). On average, this represents 21% of the total cost.
Adding up, the soft cost comes to about 66% of the cost of a solar energy system, while the hardware cost comes to about 44%.
Roadblocks to Solar Energy
Solar energy systems are like any other market segment. And, like any other segment, their prices will fluctuate depending on the performance of certain factors. For the foreseeable future, we do not anticipate any supply shortage, as solar panels are made from silicon, which is one of the most widely available materials on earth. And since the solar industry is in the middle of a boom, we also do not anticipate the research and development of newer and more improved solar energy systems to halt any time soon. So, things look good in the solar world. Demand is growing, and will continue to grow, as the actions of the world fight climate change. Supply is steady and will only become more efficient as better and more efficient solar energy systems are developed and brought to the market faster. At this point, what is likely to adversely affect the supply of solar energy systems is an inefficiency in the supply system. The biggest problem with accurately measuring soft costs associated with solar energy is that there are many jurisdictions that companies supply to. Each has its own set of rules and laws governing solar panel installations. In Australia, for example, Tasmania has a very different inspection system from the mainland. Similarly, tariffs, rebates and taxes vary from place to place and country to country. America will not have the same rebate policy as Australia, nor will China have the same supply chain costs as New Zealand. Any inefficiency in these intricate and interconnected systems will result in a lag, or a delay between the customer ordering the system and actually beginning to use it. This can be a truly frustrating experience.
The Dreaded Red Tape
Red tape is a colloquial expression for bureaucratic procedures, normally ones that tend to be long, protracted and annoying. They include inspections, permits and grid connection, among other things. No matter how efficient a government is, there will always be some red tape that will wind up annoying someone to no end. There just is no rushing the government, unfortunately, and so, some processes will invariably take their time. Now this isn’t to say that all government programs will be, tedious, drawn-out affairs. But they may well be. Technical assistance programs can ameliorate these problems by increasing efficiency and reducing costs. This can be done by engaging professionals to advise government officials on how best to speed up and streamline the process of delivery. They could equip bureaucrats with the knowledge and tools to mirror these programs on a large scale and in doing so, make your average Joe a lot less likely to want to pull out his hair. The fact of the matter is that solar energy is a relatively new technology, and its widespread adoption is likely going to pose new challenges. Australia, China and others like America are ahead of most of the world on account on how quickly solar is being adopted in these countries, but expect to see governments struggle with streamlining solar panels in the future and expect to see them improve at it.
Costs Associated with Solar Companies and Industry Professionals
Solar companies like Integra Solar hire professionals who are well versed in handling, operating and installing solar energy systems. Streamlining the solar adoption process can help make the companies’ jobs easier. As software improves, companies can pursue better leads, make more efficient sales, improve portfolio management and make financing more accessible. All of this translates to a reduction in soft costs. This reduction is then likely to be passed on to the customer as competition grows in tandem with accessibility. In addition to this, solar companies will always be in need of skilled workers; the aforementioned people who can not only evaluate your requirements, but also make recommendations based on your individual needs. The availability of properly trained recruits makes hiring new workers easy. Companies can then expand their workforce at their own pace and reduce labour costs as well.
Aside from companies, professionals and public safety officers like firefighters and paramedics will have to be trained and appraised of potential situations that may arise with the installation of solar energy systems. Though modern systems, like the ones sold by Integra Solar, tend to be extremely safe, unrelated accidents may cascade into potentially dangerous events. Public safety officers need to be appraised as to what these dangers can be, so that they can discharge their duties effectively and safely, both for themselves, as well as potential victims. Educating professionals is key to speeding up the solar adoption process.
Increasing Accessibility to Solar Energy Systems
This point is key. Accessibility is everything, when it comes to sustainability. Big car companies figured this it long ago when it came to electric vehicles. The only way we beat climate change is if EVERYONE, or at least the majority of us, can easily access an EV. The same holds true for solar energy systems. The more people have them, the more companies will try and sell them. Competition will increase, technology will improve and more people will adopt solar technology. You can probably see a cyclical pattern develop here. This is for the better. Australia already has one of the world’s best and most successful solar rebate schemes. We can all see the effect it’s had on weaning the Australian grid off that nasty coal power. With time, should solar energy systems continue to be accessible, their proliferation into every segment of society will be ensured. This will reduce many associated soft costs, thereby reducing the prices of solar adoption further.
In our next article, the last one in the series, we will delve into developments being made in the solar industry. We’ll take a look at some of the most exciting new prospects and see what path solar energy may take in the future.
How Solar Energy Systems Work (Part 5)
Welcome back to the final article in the series of how solar energy systems work. If you’ve read all the previous articles in this series, then kudos to you! You just won yourself some patented Integra Solar Brownie Points! If not, well then, we’d like to congratulate you on being a daring one and hope you learn something useful from this article. Whether you’re following along, or whether you’re just here for this article matters little. With the full series you can get a clearer understanding of what solar energy is all about, but all of these articles will work as standalones just as well. Be warned, though, some concepts mentioned in this article have been elucidated previously, so you might need to catch up on them before proceeding ahead. In this instalment we are going to take a look at the latest developments in the solar world and what the future of solar energy systems may look like.
The Race for Efficiency
As far as solar energy systems go, efficiency is the name of the game. The more efficient a solar panel is, the earlier it will provide a return on its investment, and the more profitable it will be. Modern solar energy systems in Australia take around five to eight years to return their investments. This can be squeezed down to three years or scaled up to ten years depending on factors like:
- System size
- Solar radiation levels
- Available rebates
- Sunny days per year
- Geographic limitations
- Battery packs
The one thing that can make or break a solar energy system is its efficiency and its ability to maintain that efficiency over time. Should a panel become more efficient and be able to maintain its efficiency well over time, the rate of its return on investments will considerably increase. A more efficient solar panel will produce more energy in the same time and do it longer. The solar world may be on the cusp of a major breakthrough in solar efficiency, as the global race to develop a more efficient solar panel rages from San Francisco to Shenzhen. Modern solar panels convert 17-19% of the light hitting them directly to energy. Compared to 12% just ten years ago, that is a lot, but this number may soon reach as high as 30%. As of 2020, the global share of solar energy was 2.4%. More efficient panels would mean a larger share for solar in the global energy supply. If you want proof of just how much solar energy is growing, look no further than the total installed capacity of 2020 and compare it with the installed capacity in 2010. In 2010, the global solar capacity was 20 gigawatts, and by the end of 2020 it was 600 gigawatts. Even with disruptions caused by the coronavirus, the world saw solar capacity jump by 105 gigawatts. These are impressive numbers to say the least, and they bode well for the future of solar energy.
Most solar cells are made of wafer-thin silicon slices, and about 70% of these are made in China or Taiwan. Research suggests that modern silicon-based wafers are nearing their maximum efficiency, marked by the Shockley-Queisser limit. Also called the detailed balance limit, it is “a calculation of the maximum theoretical efficiency of a solar panel made from a single p-n junction.” Before we go further, let’s understand what a p-n junction is. In the previous articles we spoke at length about semiconductors and bands between them, through which electrons move and create a current (you were warned to read the previous articles!). There is a limit to this movement of electrons, called a current, and that is the p-n junction. A p-n junction is a boundary between two types of semiconductor materials. One is the p-type, and the other is the n-type. The n-type has “holes” in it, while the n-type has an excess of electrons. The electrons move from the n-type to the p-type. The Shockley-Queisser limit has calculated that the limit of a p-n junction is at around 33.7%. At 17-19% efficiency, modern solar cells are beginning to push the limit of solar wafers. Needless to say, we still have some ways to go before we hit that limit, but when we do, we will need to find a way to expand it, or risk stagnating the solar industry. Luckily, much of the focus of modern innovation in the solar world has been on this very problem. By combining six different materials into what is being called a multi-junction cell, the limit can be pushed to as high as 47%, which is whoppingly high, all things considered. Another way is to focus the light falling on the cells by way of mirrors and lenses, though this is a prohibitively expensive method, and unlikely to become widespread anytime soon. Nonetheless, it is an avenue that may be worth exploring, as it has proven to work on satellites.
Perovskites: The New Silicon?
Named after a 19th century Russian mineralogist, Count Lev Alekseevich von Perovski, Perovskites are the fastest improving solar technology. These are tiny crystal structures that are extremely efficient for solar absorption. They work much better than silicon on cloudy days and in low-light conditions, and the best part is that you only need a layer that 300 nanometres thick (much thinner than a human hair) for effective solar absorption. Applying a layer of perovskites on any surface, like a house, a car or an entire roof could, theoretically, turn it into a massive solar energy system. Gone will be the days of solar panels on roofs and their orientation. Your whole house, or your car, or even your clothes could become efficient tools for solar energy absorption. Now, you’re probably thinking that this funny sounding material probably costs an arm and a leg. If you are, then there’s some good news for you. Perovskites are extremely cheap, just as silicon is cheap. Perovskites can be printed through inkjet printers, painted on any surface and you have an instant solar absorption system. Currently there are 10 start-up firms working on this technology, and the first perovskite based solar energy cell achieved 28% efficiency (already much higher than your average silicon cell). Perovskites can be mated with silicon solar cells to help break through the Shockley-Queisser limit. This would make a solar cell much more effective than one made of any material alone. Working in tandem, they can both absorb different bands of light (silicon absorbs the red band of visible light, while perovskites absorb the blue). One of the biggest challenges scientists are facing with perovskites is that they have been around since 2012. There isn’t enough data on whether they will have the longevity of your standard solar cells. When a material has been around for 9 years, can you really be sure it’ll last over 25?
We mentioned in a previous article in this series (another reason to go back and give them a read if you haven’t already!) that one way to increase efficiency is to make solar panels that follow the sun. This motion tracking architecture, however, can be costly and unwieldly. However, some companies are developing sun-tracking architectures that can be deployed anywhere a regular solar panel can for a minimal cost. This architecture shifts the array of solar panels by millimetres throughout the day to keep them oriented to the sun as much as possible. Another method that has increased efficiency by as much as 29%, is using tiny hexagonal lenses within a solar panel’s glass protection. This concentrates light by as much as 200%. All these technologies will definitely bump up the cost, but look at the sort of efficiency they can bring to the table. As technology develops further, costs will only go down.
Solar energy systems of the future will probably have combinations of silicon and perovskites on their wafers, hexagonal panels and miniaturised tracking mechanisms in the solar panels themselves and new, advanced shingle designs to reduce microfractures and manage external stresses. They are going to be far more efficient than the panels we use today and will prove to be excellent investments. Even if the solar industry holds its current course, and continues to eke out marginal performances of 1-2% (which are noticeable) they will still hit the magical 30% efficiency mark in due time, without significantly impacting costs. But true innovation lies in breaking through this number and going beyond what modern technology is capable of. With the aforementioned innovations, we’re willing to wager that the solar industry has what it takes to improve solar energy systems significantly and break through the Shockley-Queisser limit.