Structure and Operating Principles of Solar Panels

Greetings from DAT Solar. This article aims to provide basic knowledge about the structure and operating principles of solar panels. If you are just starting to explore the fundamentals, this article is one of the first pieces of content you should read.

In this article, we won’t reiterate what solar panels are but will delve into the details of their structure and how they work.

This article specifically focuses on the general structure of the two most commonly used types of solar panels, mono and poly. If you are interested in other types of solar panels such as thin-film, biohybrid solar panels, or concentrated PV, you can find more information here.

Structure of Solar Panels

Solar panels are divided into 8 components: aluminum frame, tempered glass, EVA layer, solar cell layer, backsheet, junction box, DC cable, and MC4 connector.

1. Aluminum Frame: This serves to create a rigid structure for integrating solar cells and other components. The aluminum frame is designed to be sturdy while ensuring a lightweight structure that can protect and secure internal components against strong wind loads and external forces. Some companies, like Canadian Solar, even anodize and reinforce the crossbars of the aluminum frame to enhance its rigidity. The common color for the aluminum frame is silver.

2. Tempered Glass: It protects solar cells from weather impacts such as temperature, rain, snow, dust, and hail (up to 2.5cm in diameter) and other external mechanical impacts. Tempered glass is designed with a thickness ranging from 2-4mm (mostly around 3.2-3.3mm) to ensure both protection and transparency for solar panels.

3. EVA Layer (ethylene vinyl acetate): Also known as the bonding material, this is two transparent polymer layers placed above and below the solar cell layer. It bonds the solar cell to the tempered glass on top and the backsheet below. This layer also absorbs and protects solar cells from vibrations, prevents dust adhesion, and guards against moisture. EVA material is capable of withstanding harsh temperatures and has extremely high durability.

4. Solar Cell Layer: Solar panels are made up of smaller units called solar cells. Common types of solar panels like mono and poly are made from silicon, a widely used semiconductor. In a cell, silicon crystals are sandwiched between two conductive layers (ribbon and busbars). A solar cell uses two different silicon layers, N-type and P-type.

5. Backsheet: It serves as an insulator, providing mechanical protection and moisture resistance. Materials used can include polymers, PP plastic, PVF, and PET. The backsheet comes in different thicknesses depending on the manufacturer. Most backsheets are white.

With technological advancements, some companies like Canadian Solar have special panel series such as BiKu, which lacks a traditional backsheet. Instead, it features a transparent tempered glass on the rear side, allowing the solar panel to absorb light from both the front and back. You can refer to the video below for more information.

6. Junction Box: Located at the rear, it is the central point for collecting and transferring the generated electrical energy from the solar panel to the outside. Because this is a central point, it is designed to be robustly protected.

7. DC Cable: This is a specialized cable for solar energy, with excellent DC insulation capabilities. It also has good resistance to the harsh weather conditions (UV radiation, dust, water, moisture) and other mechanical impacts.

8. MC4 Connector: The MC4 connector is a standard electrical connector used for connecting solar panels. “MC” in MC4 stands for the manufacturer Multi-Contact. This type of connector makes it easy to connect solar panels and arrays by manually attaching connectors from adjacent panels.

Operating Principles of Solar Panels

To explain the operating principles of solar panels, we need to start with the smaller unit: the solar cell (Solar panels are composed of multiple solar cells). As mentioned in the structure of solar panels, a photovoltaic cell uses two different silicon layers, N-type with excess electrons, and P-type with holes for excess electrons, called electron holes.

At the junction where the two silicon layers meet (P/N Junction), electrons can move through the P/N interface, leaving a positive charge on one side and creating a negative charge on the other.

You can imagine light as a stream of small particles called photons (emitted from the sun).

When one of these particles collides with a solar cell with enough energy, it can dislodge an electron from its bond, leaving an electron hole.

Electrons carry a negative charge and move freely, but due to the electric field at the P/N interface, they can only move in one direction. Electrons are drawn toward the N side, and holes are drawn toward the P side.

Mobile electrons are collected at metal strips at the top of the solar cell (ribbon and busbars). From here, they enter the consumption circuit, perform electrical functions before returning to the aluminum layer on the back.

Only electrons move within the solar cell and return to their point of origin. There is nothing worn out or depleted, so the solar cell has a lifespan of several decades.

The electricity generated by solar panels is direct current (DC). To use it for normal loads and devices, DC must be converted to alternating current (AC). That’s the function of the inverter.

Currently, many new types of solar panels are being researched and developed. Among them are types with structures and operating principles very different from what has been mentioned above. You can find more information on these in the article: Types of Solar Panels: Which One to Choose?

Conclusion

DAT Solar would like to conclude this article on the structure and operating principles of solar panels here. How do you feel about this article? If you find it helpful, please share it. If you have any suggestions for DAT Solar, please leave a message in the chatbox on the right.

Wishing you a smooth and successful day!