What are solar panels? (2021)

What are solar panels? (2021)

What are solar panels?

• Solar panels are the main component of solar systems that generate electricity
• Cells are made of semi-conductive materials such as silicon that absorb light from the sun.
• Silicon is very shiny in nature, so in order to take advantage of the photons and prevent them from reflecting away from the cell, an anti-reflection coating is applied to the cells.
• A glass cover is placed on top of the solar panel to protect the silicone material from external factors and scratching.
• The panel consists of a group of PV cells connected to one another and connected to one another
• Standard miter cells 15.6 * 15.6 cm
• The panels of 255-285 watts contain 60 cells (6 * 10) and a size of 99 * 164 cm
• The 315-335 watt panels contain 72 cells (6 * 12) and are 99 * 196 cm in size
• If a set of panels is assembled in a solar system, we call it a photovoltaic matrix or a solar array

Types of solar panels: Cell productivity map

 there are available in the markets of three main types:

1- Monocrystalline Silicon

Monocrystalline panels have a symmetrical appearance that indicates the purity of silicon crystals. 
Monoblastic cells are silicon alloys that have been sliced ​​into strips. 

You can see that the cell characters are not aligned, which gives the monochrome panels their distinct appearance as shown in the picture. These plates are the most expensive species, giving an efficiency of up to 22.5% in the laboratory, but the cells actually commercially spread in 2017 are more than 17.5% of the life span of 25 years or more

Polycrystalline silicon cells

The difference between them and monocytes is very clear in terms of shape in the two pictures, where the cells are rectangular squares. 

They are lower in price compared to monocytes. 

Its efficiency is about 16.9%. Its 25 years of life or more is the only fault that does not matter to many, but it sometimes takes into account that its appearance is not as aesthetically pleasing as the beautiful smooth blue appearance of monovalent solar panels.    

Thin Film

This type of solar panels is thin and streamlined as is evident in the picture and takes the form of the surface on which it is installed. 

Most of the developments and researches currently underway are based on development in this particular type because of its smoothness, weight and low thickness. 

Valid for many applications such as the roofs of boats and transport vehicles  from the disadvantages that it is less species efficiency Vkvaitha may not exceed 12% old default less than its counterpart unilateral and multilateral , and up to 15 years only the most expensive species price if the old default short account in the equation of the price solar

There is no preference between mono and polycrystalline poly panels in terms of electricity generation.

What are solar panels? (2021)

They have the following characteristics:

• Generate identical electricity! When comparing 100 watts of Mono cells with 100 watts of poly cells, the generation of electricity is equal to100 watts of cells being able to generate 100 watts / hour at specific laboratory conditions. Either trying to differentiate between the productivity of cells with equal capacity is funny and very naive. Because simply if the factory found the productivity of the cell when the test more than 100 watts and be like 105 will write on it 105 faster to increase its profits and to give this difference to the consumer free of charge !! So the myth is that Mono panels produce more electricity
• The sizes of the panels are identical and the space saving is very simple. When you buy a 250-265-watt solar panel from any dealer, you will find a space of 99 x 164 cm.When you search for a 270-280 Watt mono panel anywhere in the world you will find that it is 99 * 164 cm, And once again challenge anyone can come to us with a solar panel of a different area from these figures and the two types are manufactured in identical sizes until there are standard installation systems suitable for all models. The development that happens over time increases the capacity of the board while maintaining these standard measurements.

For example, when manufacturing cells and the latest model the size of the board becomes 97 * 160 instead of 99 * 264. But we find that the size remains constant with the development, but the ability of modern models It has become 285 watts instead of 250 watts two years ago Mono and Poly panels are available in the market.Currently, the Mono panels are 280 watts in size 99 * 165 while the maximum in the Poly panels is about the same size = 265 watts in space = 280-265 / 265 = 5.6% only for a lie, the Mono cells are much higher then they need much less space !!!

• The effect of temperature is also identical. At this point, superstitions spread in a large and complex manner. They speak of imaginary differences between the two types due to high temperature, ice, etc. without any scientific support, but when reading the Datasheet which is written by the manufacturers of any plate we will discover that The difference between the two types in relation to the effect of heat is a very marginal difference that has no concrete result in practical application.

How to connect a solar panel matrix

The matrix consists of several panels connected to each other in parallel or in parallel to achieve the required voltage and current design.When the series is connected, the value of the voltage multiplies and the amp remains constant. When connected to Parallel, the amp is multiplied and the voltage remains constant. Whatever the type of installation is parallel, parallel or dual, the total energy does not change. When the 10 panels are connected with 250 watts, the total power is 2500 watts, regardless of the mode of connection.

It is important that all panels be of the same type, capacity and condition. This improves the safety and performance of the slab matrix

Series

links include the positive (+) connection from the board to the negative (-) in the corresponding panel. In all the panels, in the back cable, the positive pole is supplied with a red MC4 and MC4 black cable, and a male is connected with the net in the opposite board without having to make any other connections. 

To connect 6 panels respectively with the following specifications: 

Short circuit current Isc = 8.75A Short 

circuit voltage Voc = 37.5V Total 

voltage of the matrix = 37.5 * 6 = 225v Short 

circuit current remains at 8.75A

The delivery method is chosen according to the needs and specifications of the charging regulator or alternator. For example, if the charging regulator accepts a vol = 150 volt, this means that the number of panels should be more than 4.

It is always better to select the regulator that accepts the largest number of panels in a row to increase the voltage and reduce the conductivity on the distribution. Possible. This saves the wire section and reduces system loss. 

There is a maximum limit to the voltage that the Maximum System Voltage solar panels currently have on the market. This value is equal to 1000 volts. This means that the maximum number of panels can be connected respectively = 1000 / 37.5 = 26 panel

Parallel

links include positive connection (+) of all the panels together and the connection of all negative contact points (-) with each other. In this case, two and three-way MC4 connectors should be used to make these connections. In case of increasing the number of lines connected in parallel to each other than 3 must be assembled in the Combiner Box and the use of brass bars to carry out these assemblies.To connect 6 panels in parallel: 

the short-circuit voltage remains constant at = 37.5v Combined short 

circuit current = 8.75 * 6 = 52.5 amps

It is noted here that if the distance between the panels and the charger regulator 20 meters, and we entered this data on the program of calculation of the wire section will need a wire 50 mm 2 to maintain the rate of loss of 2%, which is a very large value, which makes this connection in parallel solution It is futile for any respected engineer to understand the principles of solar cell connections. If the proposed shipping regulator is allowed to connect the panels respectively, in this case the dumpster should be thrown in the garbage and replaced with a good type,

Serial and Parallel Combination

In this method, the voltage is identical to each line of the line to be connected in parallel. 

A total of three plates are connected in parallel and two parallel lines are made with a total of 6 panels: 

short circuit voltage = 37.5 * 3 = 112 V Combined short 

circuit current = 8.75 * 2 = 17.5 amp. This matrix is ​​suitable for feeding a 112.5V In the PV panels entrance in.

 

This method of conduction is the most common method where the maximum value of the matrix array for any charging regulator is rare, which corresponds to the combined voltage of all the panels. 

If the length of the wire is 20 meters and the input of the data in the wire section calculation program as a result of the calculations it will appear that we need a 6 mm 2 wire segment which is a reasonable value other than the value we get when trying to connect all the panels in parallel.

It is worth mentioning that all current transformers for solar pump systems and network-related current transformers usually receive up to 800 volts of the panel matrix. 

Here, 20 panels are connected respectively in lines of about 5 kWh. A 20 kW solar system to feed a pump usually consists of 4 Strings lines, each line of 5 kW with a voltage of 700-800 volts.

The shipping organizations of the systems separated from the network usually receive a voltage ranging from 50 volts for systems smaller than 1 kW and 150V for medium and economic systems with capacity of 3 to 5 kW, and up to 600v in good qualities in systems larger than 3 kW.

Methods of knowing the quality of solar panels

With the naked eye and simple measuring devices, the quality of the solar panels can be determined according to the following:

What are solar panels? (2021)

Number of silver bands in the cell Busbars

The Bus Bar is the vertical metal lines found in the solar cells. They are silver wires that allow for the flow of electricity , and are connected to each other respectively to be the voltage of one cell in the solar panel 0.5 volts. 

The cost of these rails is high and represents a large percentage of the total cost of the cell.

The importance of these bars: 

1. give the durability of the cell up to 25 years old, which must withstand the difficult weather conditions of wind and temperature varying 
2. reduce the loss of productivity in the event of occurrence Cell cracks due to weather conditions
3. Two plates with 3Busbar and 5BusBar cells
4. The old and cheap models of cells have three connecting rods just as in the panel on the left. - 3BB 
5. New and commercially deployed models have 4 rods - 4BB 
6. There is also advanced cell technology with 5 bars as in the panel on the right of the picture - 5BB 
7. When buying a good board make sure that the cells are 4BB and not 3BB

Type of glass

Glass thickness of 3.2mm is usually used in manufacturing solar panels. 

This glass is rough from the double sided and this is required.

1. The inner face is heated because during the manufacturing process the cell needs to be fully bonded with the glass. The glass of the smooth glass does not hold well and will remove the lamination.

2 - The outer face is also coarse to help absorb the sun and reduce the reflection as shown in the picture

Absorption of lightThe use of coarse glass from both sides increases the cost of producing the solar panel in the cheap types of panels. The external surface, such as mirrors, can be seen when the surrounding objects are clearly visible, such as any other window panes. Unfortunately, many people think that the whiteboard Is the most quality!High-quality solar panels are made of thermo-reinforced glass, like glass.

Its carrying strength is six times the normal glass strength. 

The advantage of using reinforced glass in solar panels is to help withstand the impact of cold and wind and snow loads when broken glass breaks into small pieces harmless instead of large pieces with sharp blades such as ordinary glass. 

Cheap types of solar panels produced by small companies use ordinary glass, which can withstand weather conditions rather than causing the low productivity of panels of energy over time.

Measuring the capacity of the solar panel

An ordinary multimeter can be used to measure the solar panel

There are two different readings that must be checked to make sure that the solar panels are working properly and see how much energy they generate.

What are solar panels? (2021)

1- Volt measurement 

• Solar panels are completely separated from the battery and charging regulator 
• the board is directed towards the sun 
• ensuring that the aviometer is set to measure the voltage between the positive and negative electrode of the panels

2- Isc measurement The same steps are done, but the avmeter is set to measure current

The capacity of the board can simply be measured after reading these values ​​using the following equation 

Power = Voltage * Amps 

If the voltage reading is 37.5 and ampere 6, 

the board capacity = 37.5 * 6 = 225 watts 

The plate capacity is determined based on a laboratory test under grade Temperature of 25 ° C and special conditions in the laboratory so it is impossible to get the same value of the ability written on the board when measuring voltage and current in the previous way. But it is possible to know the efficiency of the board to be tested compared to another board to be tested at the same time and place and approximate The plate must not be less than 80% of the ability written on it, when the test in the middle of the day, Sun rays This simple test can also be used to measure and identify any faulty plate within a large package