By installing an off-grid system, you can generate your home’s electricity entirely from the sun. Of course, before installing your system, you should evaluate your energy consumption habits and determine the number of solar panels you will use in the light of these.

Besides solar panels, your off-grid system also needs batteries to store the energy you produce.

As for how big the freestanding system should be, it depends on how much electricity your home needs, how much free space you have on your roof space, how much direct sunlight the solar panels receive each day, and the type of solar panel you choose.

On average, your home will require a 7 kW solar system if you want your whole family to depend on solar energy. Please note that you can find solar panels in different sizes and shapes. There are also DIY kits available for purchase.

In addition, there is also a publicly connected solar system, which, when publicly connected, connects to the public grid and generates electricity. In this case you don’t have to rely on batteries or battery packs to store energy.

Now, the performance of solar panels is usually determined under standardized test conditions (STC). Generally, larger solar panels provide higher performance. For example, if your home requires 7 kW and you need 200 watt solar panels, you will need at least 35 panels to meet your energy needs.

If the solar system is 10 kW, at least 52 solar panels are required. Likewise, for a 20 kW scale solar system, the best option is to use 105 solar panels (positive or negative).

The following basic formula will help you understand the number of solar panels needed on your home.

• Step 1: Get your latest electricity bill. Now, check how much energy your home consumes. Energy consumption will be shown in kWh. This is the energy used.
• Step 2: After completing Step 1, calculate the hours when your roof receives enough solar energy. This is when the solar panels are at their highest efficiency. If you live in a place with enough sunlight, there is no need to look for a larger solar system.

On the other hand, if you live in a place with less sunlight, your home will need more solar panels. The important thing is to generate enough energy from the solar panels and provide the best electricity for your home. Average peak hours of sunlight usually reach 1000W/square meter.

• Step 3: Calculate the hours of available sunlight or solar energy you received in a month. Now multiply the hours by 30. Whatever you get, you must divide it by 1000 kWh.

For example, if you assume a peak sunshine duration of 5.44 hours, you multiply it by 30 and you get 163.2. Round the number to 163 and divide by 1000 and you get 6.1. Now, this 6.1 is the amount of kW of solar system your home needs.

• Step 4: Multiply the resulting number by 1000 and you will get 6100 watts. Suppose you want to buy a 200 watt solar panel system. Now divide 6100 by 200 and you get 31. Therefore, the number of solar panels you need is 31. In this way you can calculate the size of the solar system and the number of solar panels needed.

1. What is distributed photovoltaic power generation?

Distributed photovoltaic power generation is a system of photovoltaic modules built near the user’s location, where some of the energy generated is used by the user and some is fed into the grid.

Distributed photovoltaic power generation adapts to local conditions, is clean and efficient. It aims to reduce and replace fossil energy consumption by using solar energy.

2. What are the advantages of photovoltaic power generation?

• You can earn income by selling the excess electricity you generate with your solar panels to the grid, and you can also save money by purchasing electricity from the grid when the electricity you generate is insufficient. In addition, the energy you produce with your solar panels is clean and does not harm the nature.
• Insulation and cooling: Panels on your roof can cool your home by 3-6 degrees in the summer and reduce heat transfer in the winter.
• Green and environmentally friendly: Distributed photovoltaic power generation projects do not generate light pollution in the power generation process, and the emission and pollution are zero.
• A perfect combination of architecture, aesthetics and photovoltaic technology gives the roof a beautiful and impressive appearance, a strong sense of technology and increases property value.

3. If the roof does not face south, can a photovoltaic energy production system be installed?

It can be installed, but the energy production will be slightly lower and there will be a difference in energy production depending on the orientation of the roof. When facing south, the production efficiency is 100%, 70-95% when facing east-west and 50-70% when facing north.

7. Does rainy or cloudy weather affect power generation?

It would be wrong to say that it will not have an impact, but it will not have a major impact.

8. Is reduced yield a problem on rainy and cloudy days?

This is not a concern because a photovoltaic system is a grid-connected power generation system. When photovoltaic power generation cannot meet the owner’s electricity needs at any time, the system automatically receives electricity from the grid.

9. Will dust or debris on the surface of the system affect power generation?

The glass of the solar modules has a self-cleaning function that allows rainwater to wash dirt off the surface of the solar modules on rainy days.

However, factors with large shading areas, such as bird droppings and leaves, need to be removed in a timely manner.

10. Do photovoltaic systems cause light pollution?

No, In principle, the photovoltaic system uses tempered glass coated with antireflex film to maximize light absorption and reduce reflection, thus improving power generation efficiency.

No light reflection or light pollution. Traditional curtain wall glass or car glass reflects 15% or more, while the reflection rate of photovoltaic glass from premium solar module manufacturers is less than 6%.

Therefore, it has lower light reflection than glass in other industries, so there is no light pollution.

11. How to ensure efficient and reliable operation of photovoltaic systems for 25 years?

First of all, strict quality control is applied in product selection, and photovoltaic module manufacturers guarantee that the power generation of the photovoltaic module will not encounter any problems for 25 years:

• Photovoltaic module power generation under 25-year warranty to ensure module efficiency
• Having a national level laboratory (with strict quality control system in the production line)
• Large scale (the larger the production capacity, the larger the market share and the more pronounced the economies of scale)
• Strong reputation (the stronger the brand impact, the better the after-sales service)
• Focusing only on solar photovoltaic energy (photovoltaic companies and companies that only deal with photovoltaics in their subsidiaries have different attitudes to industry sustainability).

In terms of system configuration, it is important to select the most suitable inverter, combination box, lightning protection module, distribution box, cable, etc. compatible with the photovoltaic components.

Secondly, it is important to choose the most appropriate fixing method for the system structure design and fixing to the roof and try not to damage the waterproofing layer (i.e. expansion bolts should not be used for fixing to the waterproofing layer).

In terms of construction, it is necessary to ensure that the system durability is sufficient to cope with extreme weather conditions such as hail, lightning, typhoons and heavy snow, otherwise it is a hidden danger to roof and material safety for 20 years.

12. Can the cement tile structure of the roof support the weight of the photovoltaic system?

The weight of the photovoltaic system does not exceed 20 kilograms per square meter and is usually not a problem if the roof can support the weight of the solar heater.

14. How to deal with problems such as lightning strikes, hail and electricity leakage in home photovoltaic power generation safety?

First of all, equipment lines such as DC combination boxes and inverters have lightning and overload protection functions. It will automatically shut down and disconnect when abnormal voltages such as lightning strikes and leakage occur, so there is no safety problem.

Furthermore, all metal frames and handles on the roof are grounded to ensure safety in lightning storms. Secondly, the surface of the photovoltaic modules is made of ultra-strong impact-resistant tempered glass that has undergone rigorous testing (at high temperature and humidity) when certified by the European Union. In general weather conditions, photovoltaic panels are difficult to be damaged.

15. How do I determine if I can work in commercial photovoltaic systems?

Generally, the following information is needed for the assessment:

• The remaining years of the land lease or whether you own a parcel of land (with full documentation);
• Nature of electricity consumption and total annual electricity consumption;
• Total roof area and roof structure (cement, colored steel tiles, ordinary iron sheet).

16. What services are provided?

One-stop services such as scheme design, system equipment, transportation and installation, technical support for grid connection and after-sales service are offered.

17. What equipment does distributed photovoltaic power generation include?

Main equipment: solar panels, inverters, AC/DC distribution boxes, photovoltaic metering meter boxes, holders;

Auxiliary equipment: photovoltaic cables, AC cables, pipe clamps, lightning strips and lightning grounding. Large power plants also require transformers, distribution boards and other auxiliary equipment.

18. What is the installation area of distributed photovoltaic power generation?

Calculations are made based on the actual usable area of your roof. Take the 1KW example, for a pitched roof, an area of 8 square meters is required; for a flat roof, an area of 10 square meters is required. As the capacity increases, you can proceed accordingly.

19. How is my income calculated?

The income is made up of three parts: the electricity you use, national subsidies and income from the sale of electricity to electricity companies, with some local subsidies.

If you have just been introduced to solar energy systems and have had a solar energy system installed, you may be thinking that there is nothing left to do. While this is essentially true, there are many techniques to make the most effective use of solar panel systems. Getting the maximum amount of energy is not enough; it is also important to find ways to use energy efficiently. Here are six simple tips for those who want to learn how to deal with solar panels and all these energy sources:

1. Store unused energy for future use

Solar panels provide a constant source of electricity throughout the day, but you can’t usually consume all the energy produced instantly. Most people are not at home during the day and our appliances do not always work. This means that excess energy can be wasted and only used after dusk. Buying a battery to store the energy you generate allows you to use this excess energy later. A good battery is absolutely essential if you plan to completely eliminate electricity bills and become independent of the commercial electricity grid.

For many years, lead acid deep cycle batteries have been the standard choice for solar panel systems, but in the last few years, lithium ion batteries have come to the forefront, dropping in price. This is because lithium-ion batteries are more powerful, more efficient, last longer and take up less space.

Lithium-ion batteries are suitable for grid-connected and off-grid use. The model is stackable, which allows users to achieve greater flexibility and easily increase storage capacity when needed. Remember, you also need a charge controller to protect your battery from high voltage and overcharging from solar panels.

2. Make efficient use of the summer energy surge

In spring and summer, solar panels receive longer and more intense sunlight, so their energy production increases. On average, solar panel systems generate 40-50% more electricity in July and August than in November and December. It is important to find ways to use this increased energy without losing it. For example, you can utilize this surplus in an air conditioning unit. Thanks to this energy surplus in the summer, you can often install a small air conditioning system without adding a new solar panel to your home.

3. Check solar panel performance

You don’t need to go on the roof every few months to make sure your solar panel is working properly. Although the solar panel manufacturer recommends that you visually check your solar array once a year, it makes the most sense to have its operation tested by professional experts. In this article we shared, you can learn what kind of tests are performed on solar panels: https://www.solarian.com.tr/gunes-panellerine-hangi-testler-yapilir/

The importance of these maintenance and tests is much more important in professional solar energy enterprises. For more detailed information about our inspection and measurement services in accordance with IEC standards, you can read this article: https://www.solarian.com.tr/gunes-enerjisi-santralleri-ges-denetimi-ve-olcum-hizmetleri/

By establishing a Bluetooth connection with your smartphone, these systems can allow you to monitor your solar photovoltaic system 24/7. If the solar panel performance suddenly drops, you can quickly detect it and take the necessary measures.

4. Always keep the solar panel clean

If your solar panels are installed on the ground, they need to be cleaned 2-3 times a year. If you have solar panels placed on a sloping roof, rain may be enough to clean them, but after a while you may need to clean them because the dust on the solar panels will turn into mud over time. How often you need to clean solar panels depends on the area where you live.

You can call a specialized service unit to clean it or clean it yourself. It is similar to cleaning windows, but without soap.

5. Practical ways to save energy

To use solar energy more effectively, you can look for ways to reduce energy expenditure. Your electricity bills or meters can help you identify the appliances that consume the most energy at home. Some appliances may consume a lot of electricity simply because they are old, while others can be replaced with more energy efficient models. For example, LED bulbs consume less energy than traditional incandescent lamps. Also, replacing an air conditioning system with a ceiling-mounted fan can save energy.

Home appliances often consume energy in standby mode, which on average accounts for 23% of annual household electricity consumption. However, it can be difficult to constantly unplug appliances, so using smart plugs can be useful. Overall, whether you have solar panels or not, saving energy in your home can save you money and help fight global warming.

6. New ways to use solar energy

After replacing all your energy-consuming appliances with less energy-consuming ones, you may have more energy than you initially thought. Here’s how you can put this extra energy to good use:

• Garden Use: You can water your plants using an automatic irrigation system powered by solar energy.
• Electric Vehicles: A solar panel system can be compatible with electric vehicles. It can be difficult to charge electric vehicles with large energy needs, but for small vehicles such as scooters, solar energy can be quite effective.
• Energy Sharing: You can create a micro-network that shares energy with your neighbors, so you can share your excess energy with others.
• Pool Pump: You can make pool maintenance more sustainable by using a solar-powered pool pump.

These are just a few examples, but there are many different ways to use solar energy. Be creative and try to make the most of the energy.

After the installation of photovoltaic modules, many people want to produce the energy they calculated before the installation, but they encounter different results than they expected. In some cases, photovoltaic modules do not meet the expected power generation capacity.

So why are photovoltaic modules failing to meet the expected power generation? The reasons could be the following:

All these reasons can affect the power output of photovoltaic modules. You can solve the problem of lower than expected power generation of photovoltaic modules with the following recommendations

• When purchasing a photovoltaic system, try to choose as high quality and reliable photovoltaic module as possible, so that you can reduce the failure rate and ensure the maximum output power of the module.
• Module power should be considered when selecting photovoltaic modules. If more power generation is required, higher power modules should be matched accordingly.
• Attention should be paid to control and maintain the operating temperature of photovoltaic modules, and attention should be paid to the ventilation and heat dissipation of photovoltaic modules, so that the module is not affected by excessive operating temperature.
• Regularly check the cleanliness of the component surface (once a month) and clean it regularly. Pay attention to the cleanliness of the component surface during cleaning, to avoid residual dirt and blockages. The cleaning time should be selected in the morning and evening when there is no sunlight.
• After finding the appropriate installation direction and angle for the photovoltaic module and installing it correctly, everyone needs to test the irradiation of the current module position using the solar radiation meter and repeatedly adjust the position with the highest solar irradiation.

At the same time, attention should be paid to the use of this method in different seasons, and timely adjustment of the position and angle of the components according to the actual situation is important to ensure that the power generation of the components is maximized.

Once the appropriate solar panels have been selected, it is time for the installation phase. Care must be taken as optimizing the angle and direction of installation will maximize our photovoltaic energy production.

The first thing we need to do is to determine the solar radiation level in our area, we need to use the meteorological data of our location, the average daily radiation level of the previous month and adjust the light intensity of the solar panels according to the lowest and highest solar radiation levels, so that we can make the solar panels use solar energy more effectively.

One issue that cannot be ignored is that the time of peak solar radiation varies in different seasons and time zones.

Therefore, we should pay attention to adjusting the installation angles in different seasons, because the angle of sunlight fall is different in hot summer and cold winter.

At the same time, it is necessary to avoid tall buildings as much as possible when installing solar panels to ensure a more efficient use of space and avoid blocking the injection process of sunlight.

Finally, let’s choose the appropriate installation direction and angle:

Installation direction: When direct sunlight is incident on the solar panel, the maximum solar energy absorption per unit area of the solar panel is located in the north-facing south direction in the northern hemisphere and in the south-facing north direction in the southern hemisphere.

Installation angle: The tilt angle of the solar panel is determined to allow it to absorb as much solar energy as possible, and the magnitude of the tilt angle is related to your latitude.

The Earth’s axis of rotation is not perpendicular to its orbit, so the sun angle varies with the seasons, with a difference of ± 23.4 degrees. The median angle of the sun occurs at the spring and autumnal equinoxes, and at noon on the equinox the sun angle is exactly equal to (90 degrees minus latitude).

By a thorough calculation, the optimal angle of inclination should be slightly greater than its latitude in order to reach the maximum value received over the course of a year.

Photovoltaic modules are the key components of photovoltaic power generation. To ensure the normal operation of photovoltaic power generation, the components of photovoltaic power plants need to be inspected and maintained.

Hidden quality problems in photovoltaic panels or problems that appear after a period of operation of the photovoltaic power plant are difficult to detect during site acceptance, as professional equipment must be used for photovoltaic module testing.

It includes three main types of problem detection methods for photovoltaic modules, causes of hot spot formation and photovoltaic module detection methods, causes of crack formation and photovoltaic module detection methods, power reduction classification and photovoltaic module detection methods.

1. Causes of hot spot formation and photovoltaic module detection methods

A photovoltaic module hot spot is a dark spot in the photovoltaic module that is exposed to the sun and prevents some of the solar cells from working, causing the closed part to heat up much more than the open part and burn with excessive heat.

The formation of hot spots in photovoltaic modules consists of two three factors: internal resistance and the solar cell’s own dark current.

A hot spot endurance test is a photovoltaic module test to determine the ability of photovoltaic modules to withstand the heating effect of a hot spot. Photovoltaic module tests are performed at the appropriate time and process to demonstrate that photovoltaic modules can be used for a long time under certain conditions.

Hot spot detection can be performed using an infrared thermal imager. This uses a visible thermal map to show the temperature and distribution of the measured target using thermal imaging technology.

2. Causes of hidden cracks and photovoltaic module detection methods

Hidden cracks mean the appearance of small cracks in solar cells, which accelerates the power decline of solar cells and affects the normal service life of solar panels.

At the same time, hidden cracks in solar cells can expand under mechanical loads and cause open circuit damage and hot spot effect.

The formation of hidden cracks is caused by a combination of multiple factors. Unbalanced stress in solar modules or severe shaking during transportation and reshipment can cause hidden cracks in solar cells.

Photovoltaic modules undergo EL imaging testing before leaving the factory, an EL detector is used. This device uses the principle of electroluminescence of crystalline silicon and takes a near-infrared image of the solar module using a high-resolution CCD camera and detects defects in the solar module.

The EL detector can detect hidden cracks, fragments, solder points, grid fractures and abnormal conditions of single solar cells with different conversion efficiency of photovoltaic modules.

3. Power reduction classification and photovoltaic module detection methods

Photovoltaic module power reduction is the phenomenon that the output power of solar modules gradually decreases as the illumination time increases. The phenomenon of photovoltaic module power reduction can generally be divided into three categories:

The first category is the power reduction of solar modules caused by destructive factors;

The second category is the initial photo-induced reduction in solar modules.

The third category is the aging and decline of solar modules.

Among these, the first category is a controllable reduction in the installation process of photovoltaic modules. For example, by strengthening the quality of degradation, transportation and installation of photovoltaic modules, it can reduce the likelihood of hidden cracks and fragmentation in solar cells.

The second and third category are urgent process issues that need to be addressed in the photovoltaic module manufacturing process. The photovoltaic module power reduction test can be completed through the photovoltaic module I-V characteristic curve tester.

This article discusses in detail the photovoltaic (PV) module manufacturing processes, performance testing, quality criteria and production audits of Tier-1 PV module manufacturers in the solar energy sector. PV module production requires a rigorous process to ensure high quality standards and performance. The production stages start from raw material selection and preparation, through cell production, module building and module assembly. At each stage, quality control and performance tests are regularly performed. Performance tests are critical to assess the durability, efficiency and long-term performance of PV modules. The ability of PV modules to efficiently convert sunlight into electricity, their durability and longevity form the basis of quality criteria. These manufacturers generally adhere to industry best practices and high quality standards. Production audits are vital to ensure quality and compliance. These inspections monitor quality and ensure compliance at every step, starting from the selection of raw materials to the assembly stage. Continuous developments in the solar industry require continuous improvement of PV module manufacturing processes and quality standards. The combination of these elements contributes significantly to the development of reliable, efficient and sustainable PV module systems.

What is a Photovoltaic Cell?

The technology that converts solar energy into electric current is called photovoltaics (PV). Photovoltaic technology, which converts solar energy into usable power, generates electricity from light. Semiconductor materials that convert sunlight directly into electrical energy are called photovoltaic cells. Photons falling on the photovoltaic cell are converted into electrical energy. When solar radiation falls on a semiconductor material, the energy of the radiation moves the atoms in the outermost orbit of the material atoms. This phenomenon is called photoelectricity. With the movement of loose atoms, electric current is generated in conductors. Electrons do work by releasing the amount of energy they carry on the obstacles they encounter. Photovoltaic cells produced with semiconductor technology are based on silicon. Photovoltaic cells are connected in series and parallel to each other and mounted on a surface. This system prepared to increase the power output is called a photovoltaic module. Figure 1 shows a photovoltaic cell, Figure 2 shows a photovoltaic module and photovoltaic panel [1].

Monocrystalline and Polycrystalline Cell

This type of photovoltaic cell uses high purity silicon crystals as raw material. There are two main types as monocrystalline and polycrystalline photovoltaic cells.
Their efficiency is higher and their lifetime is longer than cells produced by other methods.
The crystal structures of monocrystalline photovoltaic cells are regular and therefore difficult to produce and costly.
In polycrystalline photovoltaic cells, very small amounts of defects in the crystal structure cause some decrease in the efficiency of such cells. However, the ease of production and low cost compared to monocrystalline photovoltaic cells cause an increase in the tendency towards these types of cells in designs[4].

How is a Photovoltaic Module Formed?

Photovoltaic modules are formed by connecting monocrystalline or polycrystalline cells in series or parallel to achieve the desired current, voltage and power values. These cells are soldered with the help of robots. After soldering, the cells are placed on a protective and highly absorbent material called ethylene-vinyl-acetate (EVA). The EVA is laid over tempered glass and protects the cells from external factors. Photovoltaic cells have EVA on both the front and back surfaces. On the back, a material called TEDLAR is used to protect the solar panel against UV rays, high temperature and humidity. The cells protected by EVA and TEDLAR are processed in special laminators under high temperature and pressure to form a single whole. Then, the junction box containing By-Pass diodes, which minimize shadowing effects, is inserted into the module. As a result of all these processes, the photovoltaic module becomes a power generator[1].

Photovoltaic Module Production Stages

TS EN IEC 61215 Terrestrial Photovoltaic (PV) modules – Design qualification and type approval

The IEC 61215 standard sets out IEC requirements for the design qualification and type approval of terrestrial photovoltaic (PV) modules suitable for long-term operation in general outdoor climates. This standard is intended to apply to all terrestrial flat plate module materials, such as crystalline silicon module types and thin film modules[7].

TS EN 61730 Photovoltaic (PV) module safety feature

IEC 61730 lists the tests that a PV module must fulfill for safety qualification. IEC 61730-2 and IEC 61730-1 are applied together for safety qualification[8].

The test sequence specified in this standard may not test all safety aspects that may be encountered in all possible applications of PV modules. Some issues, such as the electric shock hazard from a broken PV module in a high-voltage system, must be addressed through system design, location, access restrictions and maintenance procedures[8].

PV panel factories realize several combinations of all raw materials to be used in panel production, together with alternative brands. These combinations, including all materials and special components, are included in the Constructional Data Form (CDF). Panels are produced according to the CDF and many tests such as thermal cycle test, moisture freezing test, humid heat test, mechanical loading test are applied to these panels as required by IEC 61215/IEC61730 standards. Solar panels are entitled to receive a certificate if they successfully pass the tests according to IEC 61215 and IEC 61730 standards. After this stage, the panels have an approved CDF and IEC 61215/IEC 61730 certificates in addition to the CDF. The factory produces the panels according to the material list called BOM List and this BOM List must include the materials included in the CDF.

Cell Test

Solar cell testing is applied as the first process of solar panel production. During testing, the electrical performance of the cell is tested under a solar simulation. In addition, as a quality test, surface quality, undesirable negative effects such as breaks and cracks are checked [9]. Figure 5 shows the cell cutting machine.

Glass Loading

The glass used in solar panel production is flat or frosted tempered glass with a low iron oxide content. The low iron oxide content increases the light transmittance of the glass. In the production line, the glass is loaded precisely by automatic robot arms. The high precision of the robot arms minimizes the risk of glass breakage and cracking during loading. After the glasses are loaded, they undergo surface control and cleaning processes. At this stage, cracks and deformations on the surface are detected [9]. Figure 6 shows the PV module glass and Figure 7 shows the glass loading machine of a factory producing PV modules.

Foil Laying Line

EVA (ethylene vinyl acetate) solar film is used in solar panel production systems to make electricity generation more efficient and to protect the cells against impacts. In this production line, EVA foils are combined between the glass and the cells[9]. Figure 8 shows the EVA laying machine.

EVA is a special layer that lies between the glass and the cells, as well as between the cells and the backsheet. Applied on both sides, the EVA is melted by hot lamination and completely wraps the solar cells. This process increases the durability of the panel and prevents elements such as water and micro-dust from leaking in. It also protects the solar cells by absorbing impacts and vibrations[14].

Stringer and Soldering Line

Once the microcracks and deformations on the solar cells are detected, the cells are carefully aligned on the production line. Stringer machines perform the soldering process using infrared or laser after spraying solder paste on the cells[9]. Figure 9 shows the stringer machine. In the stringer machine, conductive wires called ribbons are soldered onto the cells. Figure 10 shows a visual of the soldering process.

Lamination Line

After the PV module leaves the stringer area, it is sent to the lamination line with EVA material again on the back side and either AR coated glass or a backsheet called backsheet is laid on it. Here, at high temperature and pressure, all materials are intertwined and become a whole.

Backsheets are the outer layer of solar panels and provide electrical isolation of the internal circuits from the external environment. This layer plays a critical role in protecting the panel from harsh environmental conditions. It increases the durability of solar panels throughout the panel lifetime and reduces the safety risk[14]. Figure 11 shows the backsheet used for the PV module. In the lamination line, the EVA material must melt completely at a constant time and temperature to obtain a transparent appearance and a very good grip on the cells and the entire panel [9]. Figure 12 shows the lamination line.

Press Line

After the edge trimming and cutting of the panels and frames are done, they are sent to this line for the fitting of the frame. After the frame process is completed, the connection box is mounted to the panels [9]. Figure 13 shows the frame press line. Aluminum frames used in PV module production are important components that require attention to factors such as the appropriate design of mounting holes, set weights, coating thickness and the proportions of the elements in the content. Low iron content in aluminum frames reduces the risk of corrosion and anodized coating prevents tarnishing [14]. Figure 14 shows the frame.

Connecting Junction Box

A junction box is attached to the modules coming out of the frame. The junction box, which connects the cells in photovoltaic solar panels in series, protects the panel electrically by transmitting the generated electricity to external lines. The diodes inside provide protection against UV rays from the sun. At the same time, this box provides access for the detection and repair of malfunctions that may occur in the panel [14]. Figure 15 shows the connection box.

The raw material checks carried out during the production audit should also be carried out for backsheet, junction box and frame. The point to be considered here is that the brand models of these products are included in the CDF. If we consider this issue especially for the junction box, there are three issues to be checked. These are bypass, cable and connector. These three elements make up the junction box. Each junction box brand can use different products for these three elements. For example, a bypass diode coded as 4045 can be used in a junction box with a rated current of 25A, while 5045 can be used for 30A. These combinations must also comply with the CDF.

Tests Applied within the Scope of IEC 61215/IEC 61730

Visual Inspection

PV modules are inspected for the following conditions under an illumination of not less than 1000 lux.

-Cracked, warped, misaligned or torn outer surfaces

-Broken, cracked cells,

-Faulty connection points or joints,

-Cells in contact with each other or with the frame,

-Disorder of adhesive bonds,

-A continuous path between a cell and the edge of the module formed by bubbles or folds,

-Bonded surfaces of plastic materials,

-Faulty terminations exposed to live electrical parts,

-All other conditions that may affect performance [22].

Electroluminescence (EL) images of PV modules are used to detect micro-fractures that are not visible to the eye.

Electroluminescence images are usually obtained in dimly lit environments and are usually grayscale. Defects in such images usually appear in dark regions; in particular, fractures and other defects appear as black lines or dark spots. Electroluminescence imaging is a widely used defect detection method in many manufacturers[23]. Figure 16 shows the EL image of the PV module.

Maximum Power Determination

PV module power is determined at 1000W/m² irradiance and 25°C temperature[22].

Insulation Test

This test determines whether good insulation is provided between the current-carrying parts of the module and the frame or surroundings. The insulation resistance of modules with an area of less than 0.1^m2 shall not be less than 400 MΩ. For modules with more than 0.1^m2, the value of the insulation resistance measured at 500 V or the maximum system voltage, whichever is greater, multiplied by the module area should not be less than 400 MΩ x^m2 [22]. Figure 17 shows the TSE insulation test cabinet.

Measurement of Temperature Coefficients

Monocrystalline and polycrystalline cells with crystalline technology decrease in power as the temperature increases. The low temperature coefficient reduces energy loss when the temperature rises. When the module reaches the desired temperature,_ISC, _VOC and peak power are measured. The module temperature is varied in steps of about 5°C over the range of interest of at least 30°C and the_ISC, _VOC and peak power measurements are repeated[22]. Figure 18 shows the relevant experiment.

Hot-Spot Endurance Test

The purpose of this experiment is to determine the module’s ability to withstand hot spot heating effects, for example solder melting or housing degradation can create a heating effect. This defect can also be enhanced by cracked or mismatched cells, interconnected defects, partial ghosting or blemishes. There should be no visible defects, the reduction in maximum output power should not exceed 5% of the value measured before the test and the insulation resistance should meet the initial measurements[22].

Ultraviolet PreconditioningTest (UV Preconditioning Test)

The PV module is preconditioned with ultraviolet (UV) radiation to identify materials and adhesive binders that are sensitive to UV degradation prior to thermal cycling/moisture freezing experiments. The temperature of the module is exposed to UV radiation with a wavelength band between 280 nm and 385 nm, totaling 15 kWh/m2^,at 60ºC ± 5 ºC, while irradiated with UV light. [22].

Thermal Cycling Test (Thermal Cycling Test)

The ability of the PV module to withstand thermal mismatch, fatigue and other stresses caused by repeated changes in temperature is determined. 50 and 200 cycles are applied in the range from -40 °C to +85 °C. During the experiment, there should be no interruption in the current flow[22].

Humidity-Freeze Test

It determines the ability of the PV module to withstand high temperature and humidity effects following sub-zero temperatures. This is not a thermal shock test. 10 cycles are applied at +85 °C and -40 °C, 85% RH relative humidity[22].

Damp-Heat Test

It determines the ability of the PV module to withstand humidity and long-term penetration effects. 1000 hours, +85 °C, 85% RH relative humidity test is applied[22].

Wet Leakage Current Test (Wet Leakage Current Test)

This test evaluates the insulation of the PV module under wet operating conditions and verifies that moisture from rain, fog, dew or melted snow does not enter the active parts of the module circuit to cause corrosion, ground fault or safety risk[22].

-Resistance: 3,500Ω or less

-Surface Stress: 0.03 N/m or less

-Temperature: 22 ºC ± 3 ºC

For modules with an area of less than -0.1 m², the insulation resistance should not be less than 400MΩ. For modules larger than 0.1 m², the measured insulation resistance multiplied by the area of the module should not be less than 40 MΩ.m² [22].

Mechanical Load Test (Mechanical Load Test)

The purpose of this experiment is to determine the resistance of a photovoltaic (PV) module to wind, land, static loads or ice loads. During the experiment, the module is fed to continuously monitor the electrical integrity of the module’s internal circuitry. A load of 2400 Pa is applied to its front and back surface for 1 hour for three cycles[22].

2400 Pa is considered as a reference for strong winds with a safety factor of 3 and a speed of 130 km/h (approximately ± 800 Pa). If the module must withstand heavy snow or ice accumulations, the force applied to the front surface of the module is increased from 2400 Pa to 5400 Pa for the last cycle. During the test no continuous open circuit fault should be detected and there should be no major visible defects. Also, the reduction in maximum output power should not exceed 5% of the value measured before the experiment[22].

Electroluminescence (EL) Imaging

Early detection of defects in photovoltaic panels is critical to ensure the efficiency, reliability and longevity of the systems. Defects can reduce panel efficiency, limit energy production and pose safety risks. These are detected through methods such as visual inspection, electrical testing and performance monitoring, and are carried out by specialized teams. Electroluminescence (EL) imaging, in particular, is widely used as a method to highlight fractures and other defects in panels. EL devices detect defects by capturing the radiation generated by DC power applied to the panels with special cameras. This process is necessary to improve the performance and lifetime of the panels during production and operation and must comply with local regulations. Detection and elimination of defects ensures optimum performance of the system, reducing operating costs and increasing environmental benefits [23].

Author:

Melisa Ekşi

In May 2021, under YEKA SPP-3, the SPP capacity allocation tender for 1000MWe in total with 74 different projects in 36 different provinces was finalized. Full details on the tenders can be found here. According to the tender documents, the winning price is revised every 3 months according to the following tender document formula.

According to the formula, the winning price started to run in July 2021. The first change took place in October 2021 and the second change took place in January 2022. Based on the initial price as an index value, there is an increase of 17.76% in TL terms and a decrease of 25.33% in USD terms as of January 2022.

If we consider the winning bid as 25kr/kWh, the sample price change is as follows.

Year	Moon	kr/kWh	TL	$cent/kWh	USD % 2021
2021	July	25.00	–	2.90	–
2021	October	26.66	6.63%	2.92	0.48%
2022	January	29.44	17.76%	2.18	-25.33%