The discovery of the photovoltaic effect in 1839 by Edmond Becquerel laid the foundation for solar technology. Decades later, significant advancements, including the development of silicon solar cells in the 1950s, paved the way for the widespread adoption of solar energy in the modern era.
Since then, solar energy has grown cheaper as PV panels have become more efficient, lighter, and more refined in appearance – prompting a surge in demand. The global solar power market is anticipated to grow substantially between 2021 and 2029, with estimates suggesting an increase of around 123%.
But what goes into a PV module, and how is it made? This article explores the raw materials used to make solar panels, from the cell itself to components like busbars and junction boxes.
What Is A Solar PV Module And Its Components
A solar, or photovoltaic (PV), module is a device that converts sunlight into electricity, making it the key component of a solar energy system.
Solar panels convert sunlight into direct current (DC) electricity. This DC electricity is then directed to an inverter, which converts it into alternating current (AC) electricity compatible with most appliances and the power grid.
A PV module consists of several essential components, including:
1. Solar cells 2. Busbars 3. Encapsulant 4. Backsheet 5. Frame 6. Glass 7. Junction box
These components are assembled in a solar panel manufacturing process that involves several steps and specialized machines, each completing a specific step in creating the module.
For example, stringers connect the solar cells, foil cutters cut and place the backsheet onto the module, and framers place the module inside a frame. For a complete review, read our article on solar panel machines.
Solar Cells
Just as PV panels are the heart of a solar energy system, solar cells are the most critical component within a PV panel. They are responsible for capturing energy from the sun and converting it into usable electricity.
A solar module consists of multiple solar cells, typically 60 or 72, which are wired together. Each cell is made from a thin wafer of silicon and connected to the others in the module by thin wires known as busbars.
Solar cells are the most expensive part of a solar panel, and their quality varies depending on the material they are made from. Silicon cells, for example, are generally more expensive but also more efficient than thin-film cells. This higher efficiency is the main reason production focuses on silicon panels, which account for 90% of the solar PV panels on the market.
Busbars
Busbars are thin, conductive strips, typically made of copper or aluminum, that collect and distribute the electric current generated by individual solar cells. Positioned on the surface of the cells, they connect them electrically to form a complete circuit within the module.
The number of busbars can vary depending on the cell design and desired efficiency. While adding more busbars generally reduces resistance and improves current collection, it can also slightly decrease the light-receiving area. To address this, newer technologies like multi-busbar cells and busbarless designs are being explored to further optimize efficiency.
Glass
Solar PV modules need protection from environmental factors like moisture, dirt, and physical impacts while still allowing sunlight to reach the solar cells. This is where the glass comes in.
However, modules don’t use ordinary glass. They rely on tempered glass, typically 3.2mm thick, which is up to six times stronger and more durable than the regular kind. The glass is also treated with an anti-reflective coating to reduce reflections and maximize the amount of sunlight reaching the solar cells.
This design’s primary purpose is to transmit as much sunlight as possible into the module while ensuring high solar radiance transmittance and a low reflection rate.
Backsheet
The backsheet is a protective layer on the rear of the module, typically made of a multilayer polymer material like polyvinyl fluoride (PVF) or ethylene-tetrafluoroethylene (ETFE). The backsheet also provides electrical insulation, helping to prevent shocks and short circuits.
The primary purpose of the backsheet is to protect the solar cells and other components from moisture, dirt, and other environmental factors. This lengthens the lifespan of the module and maintains its performance over time.
A quality backsheet can also reflect light back onto the solar cells, slightly increasing the module’s efficiency.
Encapsulant (EVA)
The encapsulant is a thin layer of polymer material applied to both the front and back of the solar cells within a module. It serves several critical functions:
Protection: It safeguards the cells from environmental factors like moisture, dirt, and other external elements.
Mechanical support: It provides structural support for the cells, holding them in place and preventing physical damage or movement.
Electrical insulation: It electrically insulates the cells and other components within the module.
Light transmission: It allows for optimal light transmission to the solar cells, minimizing any potential absorption or blocking.
Frame
The frame gives a solar module its structure, holding all the components together. Usually made of aluminum or stainless steel, it wraps around the edges of the module and provides a sturdy structure for mounting.
Junction Box
The junction box is a small plastic or metal case on the back of the module that houses and protects the electrical connections. It is designed to shield these critical components from moisture and dust, ensuring a safe and reliable link between the solar panel and the rest of the power system.
The Importance of Quality Raw Materials
From solar cells and busbars to the junction box and frame, each part plays a vital role in the module’s overall performance, efficiency, and longevity.
The quality of these materials is crucial for producing high-quality solar panels. For example, faulty solar cells or busbars can increase the internal resistance of the module and cause it to heat up, creating a potential safety hazard.
Similarly, poor-quality encapsulants, backsheets, or frames can wear away easily, allowing moisture to seep into the module and damage the sensitive solar cells. A faulty junction box or its connectors will directly reduce the module’s output.
This is why it’s critical for manufacturers to find reliable suppliers of raw materials. Module manufacturing is an increasingly competitive industry. To compete at the highest level, companies must consistently produce quality products, and that process begins with sourcing superior materials.
Get the complete checklist for manufacturing high-quality panels.
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