In order to help power our sustainable future, we are always searching for solar panels that perform better and are more efficient. However, regardless of how efficient a panel is, location-based implications may affect its performance. The tilt angle and orientation may have a positive or negative impact on performance, and finding the optimal tilt angle and orientation in every environment can be challenging. Solar trackers and other potential solutions might be useful in resolving some of these concerns, but in most circumstances, implementing them would not be cost effective. A research team at Stanford has increased the effectiveness of photovoltaic (PV) systems, even on overcast days, by focusing the light that hits the solar cells without using any moving components. This method is more effective than constructing solar cells that are more efficient or monitoring the sun. Is it really that easy to increase the amount of power generated by solar panels? Let’s see if we can reach a conclusion on this, shall we?
Over the last several years, I’ve written quite a bit on the many developments pertaining to solar panels. In a previous video, I briefly discussed recent solar panel efficiency developments expected to occur in 2022. We went through some of the most interesting new developments, as well as the benefits and drawbacks of solar panels, and my current perspective on the topic. The fact of the matter is that solar panels have become efficient enough in recent years to provide a significant portion of the energy requirements that are likely present in your house. Nevertheless, there are still a number of factors that influence the amount of power they produce, and orientation and tilt angle are only two of them. Solar panels have certain requirements for their tilt angle and orientation to maximize the amount of sunlight they absorb and achieve optimum efficiency.
Geographic location is a very important consideration when it comes to the orientation of solar panels. It is recommended that you position your solar panels such that they face south if you reside in the northern hemisphere. The opposite is true for you if you are located in the southern hemisphere. Consider a house in the northern hemisphere with a horizontal roofline, meaning that it has a roof facing both the north and the south. This will help you comprehend this concept better. Since the sun rises in the east and sets in the west, travelling in an arc towards the equator line, the side of the structure facing north is generally in the shadow during the day. The west side of the building is in the shadow while the east side is exposed to the early sun. When the sun begins to set, the eastern side is in the shadow, while the western side is illuminated by the sun. Because of this, the side of the home that faces south will be subjected to an increased amount of sunshine throughout the duration of the day. If you turn solar panels so that they face any other direction, you should anticipate a big reduction in the amount of electricity they produce. Solar panels installed on homes that face east or west will generate around 15% less energy, while solar panels installed on homes that face north would suffer losses of roughly 30%. As a result of the fact that my home does not have a roof that faces south, the solar panels on my property are oriented in such a way that they do not achieve their optimum output throughout the course of the day. I was aware of it going into it, so I tried to compensate for it by adding as many panels as I could manage.
The tilt angle, which is simply the vertical angle of your panels, is the other key component to take into consideration. The angle at which the sun’s rays hit the surface of your solar panel should be as close to 90 degrees as possible, since this ensures the maximum amount of energy is generated from the sun. In most cases, the latitude of your property will determine the appropriate tilt angle for your solar panels, or it will be quite near to that value. The more you go to the north, the steeper the angle your panels should be inclined. When placed in this orientation, the solar panels will face the point in the sky when the sun is at its maximum elevation in the summer and its lowest elevation in the winter. The correct tilt angle, however, varies depending on the time of year, which in turn lowers the amount of electricity that can be generated by solar panels that are permanently installed. Again, if you are considering having solar panels placed on your house, a solar installer will consider all of this before determining the anticipated amount of solar power that your home will generate.
Solar panels should be installed at an angle of between 30 and 45 degrees for maximum efficiency, according to the majority of property owners in the United States. However, in practice, PV installers confront difficulties in reaching the appropriate angle for their panels. Most residential systems are designed to match the pitch of the roof, which results in either a greater or lower tilt angle. Other factors, like as the available roof space, the smallest gap between rows of PV modules, the space for a maintenance operation, the prevention of individual panels from casting shadows on one another, and the accumulation of dust, may also have an effect on generation.
The amount of energy that is lost was quantified by researchers from the University of Oviedo, which brings up an interesting point. Compared to the optimal tilt angle, changes in tilt angle of up to 10 degrees have less than a one percent influence on the amount of solar irradiation received. On the other hand, the solar panel’s energy output is reduced by 10% if the tilt angle variations range from 31 degrees to 33 degrees.
For instance, a solar panel angle of 41 degrees is optimal for meeting the requirements of New York’s winter and summer climates respectively. If, on the other hand, the tilt angle of the panels is closer to 30 degrees, the yearly average solar radiation will be 4.46 kWh/m2 per day. On the other hand, the solar radiation falls to 4.02 kWh/m2 per day when the angle is reduced from 5 degrees to 5 degrees. It seems that the expected amount of power that a system may produce with a capacity of 5 kW would drop from 6,075 kWh to 5,438 kWh. According to these data, the solar panel with a tilt angle of 30 degrees would save an annual amount of $1,215 on their energy bill, while the solar panels with a tilt angle of 5 degrees will save an annual amount of $1,088.
Solar tracking systems have the potential to increase the amount of photovoltaic energy produced throughout the year. As the sun travels across the sky, the solar tilt angle must be adjusted by a solar tracking system so that it remains aligned with the sun. It employs sensors to track the movement of the sun and a control system to operate electric motors that will continuously alter the position and tilt of the solar array. This allows it to maximize the amount of energy harvested from the sun. There are essentially two distinct categories of tracking systems. Single-axis tracking devices tilt on a single axis, following the sun’s movement in either a vertical or horizontal plane throughout the day. Dual-axis tracking systems are designed to follow the horizontal and vertical movement of the sun. An increase in energy production of 10–30% may be achieved with a solar panel array equipped with a single-axis solar tracker. For instance, adding a solar tracker to a fixed 1.28 MW PV system in Melbourne, Australia, which now generates 4,612.01 kWh/day, will cause the system to yield 5,783.71 kWh/day.
Trackers may function in one of two ways, either by using a timer or a sensor, or in some hybrid fashion that combines the two methods. Timers may be configured for a particular latitude, and once they have that information, they will automatically turn the solar panels in the direction that will expose them to the most sunlight at the given day and time for that latitude. The “sweet spot” for the optimum amount of solar energy may be located by the use of photoelectric sensors. A sensor is positioned above the axis of a single-axis tracker, while another sensor is mounted below the axis. If one of these light sensors detects that there is more light than the other, it will trigger a relay that will send a signal to a motor that will move the panel until the light is evenly distributed between the two sensors.
Timers are easy to use overall, but they are particularly vulnerable to being affected by clouds. Imagine that an annoying cloud keeps getting in the way; the timer has no way of knowing this, so it keeps pointing directly towards the cloud. On the other hand, photoelectric sensors would notice the imbalance and point away from the predicted ideal position to discover the optimal location, which may be a few degrees away from direct sunlight. One of the drawbacks of utilizing photoelectric sensors is the necessity of developing an algorithm that prevents the system from “chasing the sun” and continuously moving position. Because each movement consumes power and lowers the system’s overall efficiency, this can be considered a disadvantage.
The disadvantage of using mechanical solar tracking systems is that they are more expensive and typically have higher installation and maintenance costs. Since these systems have more moving parts, they are more likely to malfunction, which can cause the system to be inoperable for a period of time that can range from a few hours to several days. Because trackers are too heavy to be used on roofs, they are often placed using a ground-mounted system, which restricts the types of situations in which they may be used.
Let’s assume you put in 15 ground-mounted solar panels, each of which has a power rating of 300 watts; this would give you a total of 3,600 watts. If purchased, this system would have a total price tag of $14,625. A solar tracker may be added to this system for an extra cost of $500 per solar module, bringing the total cost up to either $22,125 for a single-axis system or $29,625 for a dual-axis system. The savings on yearly energy consumption with such systems range between around $1,430 and $1,540, which is just a little bit more than the savings of $1,100 with a stationary PV system. In addition, the operation and maintenance expenses (O&M) for a one-axis tracker are $14/kW annually. We can see the difference if we compare this to the cost of a fixed utility-scale PV system, which is $13/kW per year. You can probably understand why many people believe that using solar trackers is not worth the initial increased cost when you can instead simply add a few additional fixed panels to make up for the output gap. This is because solar trackers follow the sun as it moves across the sky.
Because of these drawbacks, researchers have been pushed to explore new technologies that may boost solar output while maintaining prices at a reasonable level. Concentrated photovoltaics is one of the technologies that is currently being researched (CPV). To provide a general overview, photovoltaic systems that concentrate light energy do the same thing as ordinary photovoltaic cells, which is to say, transform light energy into electrical energy. The concentrator photovoltaic (CPV) technology differs from other solar power generation methods in that it incorporates an optical system that focuses the sun’s rays onto a relatively small solar cell that has a high conversion efficiency. This allows for the production of more usable electrical power. These sorts of devices are comparable to telescopes that are pointed in the direction of the sun and provide the cell with focused light.
In today’s solar photovoltaic technology, lenses or mirrors are used to reflect and focus the sun’s rays. Because I’ve previously produced a film on concentrated solar power that uses mirrors, I’m merely going to concentrate on CPV that uses lenses. These systems use an optical component that gathers sunlight and focuses it onto a miniature solar cell with a high efficiency. This kind of solar cell is known as a multi-junction solar cell and is responsible for converting solar power into electricity. In most cases, a multi-junction solar cell is made up of three individual solar cells that are wired together in series. Compared to a conventional solar cell with a single junction, which typically has an efficiency of approximately 20%, a multijunction solar cell may achieve a greater conversion rate (sometimes up to 40%), thanks to each layer captures a distinct wavelength of light. The amount of energy that is produced by this cell significantly increases when the sunlight that hits it is focused and concentrated on it.
There have been three distinct categories defined for the various CPV system designs. If the magnification ratio is less than 10X, the concentration is considered low; if it is between 10X and 100X, the concentration is considered medium; and if it is between 100X and 1000X, the concentration is considered high. If you focus 10 or 100 times more light onto a correctly built CPV cell, you should be able to create more than 10 or 100 times the amount of power. This is a very simplified explanation.
The low concentration PV module that Zytech Solar manufactures is a good illustration of a CPV system. By adding mirrors to the sidewalls and using prismatic lenses to focus the sunlight, it achieves a concentration level of 2.25X. This results in an increase in energy output that is anywhere from 1.8 to 2 times more than that of a conventional PV installation.
In order to generate the same amount of energy as conventional solar power, these alternative forms of solar systems need far less land area than traditional solar power plants do. Having said that, this does come at a greater expense. In comparison, conventional solar panels cost just $0.70 per watt, whereas concentrated photovoltaic panels may cost up to $1.10 per watt. Maintenance is another concern, particularly in light of recent additions like tracking and cooling systems. The CPV power plants in Puertollano, Spain, have an annual operating and maintenance cost that falls anywhere between 20 and 30 euros per kilowatt (the current values in USD are basically the same).
A team of researchers at Stanford University created a non-tracking concentrator device with this concept in mind. This gadget has the advantage of enhanced power production without the need for any moving components. They have given their novel immersion graded index optic system the name AGILE, which was presented in the Microsystems & Nanoengineering journal issue published in July. It is a device that has the form of an inverted pyramid with the tip at the bottom cut off. It is designed to collect sunlight from any incidence angle and focus it on a tiny area. It does this by directing sunlight coming in from the inside, which features reflecting sides that funnel the light down to produce a brighter output point on the bottom. This works for sunlight coming in from practically any angle.
It was essential to the success of AGILE’s design that the materials used were tough, transparent, and reasonably priced. The Stanford research team created a graded index material by layering together several glasses and polymers that bend light to varying degrees. This resulted in the creation of prototypes of the material. The authors note that AGILE can be manufactured via the use of 3D printing and the aforementioned everyday materials. Because it is very straightforward to adjust the composition of the feedstock as the additive manufacturing process develops, this may make the manufacturing process simpler, which can simplify the manufacturing process. You are able to make a gradual shift from one substance to another. People sometimes call this kind of production “functionally graded” or “functional gradient.”
They evaluated two separate prototypes, and both of the prototypes displayed a 3x optical concentration and reached a 90% efficiency in catching light. Therefore, it is not difficult to envision how significant of an influence this may have on the solar panels that are now in use. You may lower the amount of solar cell area required to create electricity by adding a layer of AGILE to the top encapsulation layer that shields a solar panel. This would need some modification to the existing layer. Additionally, it would assist in mitigating the unfavorable impacts that are brought on by the tilt and orientation of the panel. Compared to conventional solar trackers and CPV systems, this system’s advantages might lower the costs of manufacture and installation while simultaneously boosting the amount of solar energy produced. It’s pretty much the same as obtaining the advantages of tracking systems without the moving components or the maintenance difficulties that come along with them.
The fact that AGILE is still only used on a lab scale is an obvious drawback. However, the researchers claim that their technology offers lower prices, more design freedom, and scalable fabrication processes to simplify implementation using standard materials and production through 3D printing. Evidence suggests that optical devices constructed using 3D printing may retain or even surpass the surface quality of those constructed using conventional methods. This could make the production process go faster, be easier to scale up, and cost less.
As we progress toward a future that is more sustainable, we must make advancements in the production of solar energy. It is not enough to just improve performance at any expense; rather, we need to come up with innovative and ingenious methods to design our way around the challenges we are facing in a cost-effective and sustainable manner. PV tracking systems already exist, but they represent a more specialized approach because of the additional costs and difficulties. On the other hand, something similar to AGILE has the potential to become a solution that can be implemented on a rather massive scale. Simply said, we cannot rush this process since there is still a significant distance to go before we can take this product public.