Photovoltaic (PV) modules - PV modules remain core tech, evolving toward higher efficiency and bifacial designs for tracker use.

A photovoltaic (PV) module, commonly known as a solar panel, is the core component of a solar energy system. It is a packaged, weather-tight assembly of interconnected solar cells that convert sunlight directly into electricity through the photovoltaic effect.

How a PV Module Works
A PV module operates on a fundamental scientific principle:

Solar Cells: Each PV module is composed of numerous small, individual solar cells. These cells are made from a semiconductor material, most commonly silicon.

Absorption of Photons: When sunlight (composed of photons) strikes the solar cell, the semiconductor material absorbs these photons.

Creation of an Electric Field: The absorbed energy from the photons knocks electrons loose from their atoms, creating a free electron and a "hole" (the space left by the electron). A built-in electric field within the cell directs these free electrons and holes in opposite directions.

Generation of Current: The directed flow of electrons creates a direct current (DC). This current is collected by a network of metallic contacts on the surface of the cell.

Module Assembly: Individual cells are connected in a series to increase the voltage and then in parallel to increase the current. This assembly is then encapsulated between protective layers, usually tempered glass on the front and a polymer backsheet, and sealed in a durable aluminum frame to protect the fragile cells from environmental factors.

Types of PV Modules
The type of PV module is primarily determined by the kind of silicon used to make the solar cells.

Monocrystalline Silicon Modules: These are made from a single, continuous crystal of high-purity silicon.

Pros: They are the most efficient type of PV module, with efficiency ratings often exceeding 20%. Their single-crystal structure allows electrons to move more freely, leading to a higher power output in a smaller footprint.

Cons: The manufacturing process is more complex and energy-intensive, making them more expensive than other types. They have a characteristic dark, almost black appearance with rounded edges.

Polycrystalline Silicon Modules: These are made from multiple silicon crystal fragments melted and poured into a mold.

Pros: The manufacturing process is simpler and less wasteful than monocrystalline modules, making them more affordable.

Cons: They are less efficient than monocrystalline modules, with typical efficiency ranging from 15-17%. Their multi-crystal structure gives them a distinctive blue, mottled appearance.

Thin-Film Modules: These are a newer technology made by depositing very thin layers of photovoltaic material onto a substrate like glass.

Pros: They are lightweight, flexible, and can be produced at a lower cost than crystalline silicon modules. They perform well in low-light and high-temperature conditions.

Cons: They are significantly less efficient than crystalline silicon modules. The most common types, like Cadmium Telluride (CdTe), are also a point of concern due to the use of toxic materials.

Key Characteristics
When evaluating PV modules, several key characteristics are considered:

Efficiency: This is the percentage of sunlight that a module can convert into electricity. Higher efficiency means more power can be generated from the same amount of space.

Power Rating (Wattage): This is the maximum power a module can produce under standard test conditions. Typical residential modules range from 300 to over 400 watts.

Temperature Coefficient: This value indicates how a module's power output is affected by an increase in temperature. A lower temperature coefficient is better, as it means the module's performance is less affected by heat.

Durability and Warranty: PV modules are designed to last for a long time, with a lifespan of 25-30 years or more. Manufacturers typically offer a 25-year performance warranty, guaranteeing a minimum percentage of the original power output.