What Are Solar Panels?Working Principle
A solar panel is a device that absorbs sunlight and directly or indirectly converts solar radiant energy into electrical energy through the photoelectric effect or photochemical effect.
Material Composition
A solar panel mainly consists of tempered glass, EVA (Ethylene Vinyl Acetate), solar cells, a backsheet, an aluminum alloy frame, a junction box, and silica gel. Among these components, silicon is the core material. Their respective functions are as follows:
- Tempered glass: Protects the solar cells while allowing sunlight to pass through.
- EVA: Bonds and fixes the tempered glass to the solar cells (or “bonds and secures the tempered glass and solar cells together”).
- Solar cells: The core component responsible for generating electricity.
- Backsheet: Provides sealing, insulation, and waterproofing.
- Aluminum alloy frame: Offers structural support and enhances the panel’s sealing performance.
- Junction box: Protects the entire power generation system and acts as a “current transfer station”.
- Silica gel: Seals the joints between the panel and the aluminum alloy frame, as well as between the panel and the junction box.
Working Principle
Taking crystalline silicon (the most common material) as an example:
- P-type crystalline silicon is doped with phosphorus to form N-type silicon, creating a P-N junction.
- When sunlight hits the surface of the solar cell, some photons are absorbed by the silicon material.
- The energy of these photons is transferred to silicon atoms, causing electrons to “jump” (i.e., become excited) and turn into free electrons.
- These free electrons accumulate on both sides of the P-N junction, forming a potential difference.
- When an external circuit is connected, the electrons flow through the external circuit under the influence of this potential difference, generating an electric current—thus converting light energy into electrical energy.
Material Classification
- Crystalline silicon solar panels: Include polycrystalline silicon solar panels and monocrystalline silicon solar panels.
- Monocrystalline silicon panels have a higher photoelectric conversion efficiency (up to 24%) but also a higher production cost.
- Polycrystalline silicon panels have a slightly lower efficiency (around 16%) but are more cost-effective.
- Amorphous silicon solar panels: Such as thin-film solar panels and organic solar panels. They feature a simple manufacturing process and low silicon material consumption, and can generate electricity even in low-light conditions. However, their photoelectric conversion efficiency is relatively low, and their performance is less stable over time.
- Dye-sensitized solar panels: A type of chemical dye-based solar panel, e.g., dye-sensitized solar cells (DSSCs).
Application Fields
Solar panels are widely used in industries and scenarios including transportation, communications, petroleum, marine operations, meteorology, lamp power supplies, photovoltaic (PV) power plants, and solar-integrated buildings. Specific applications include:
- Residential and off-grid solar power systems: Providing electricity for remote off-grid areas with no access to traditional power grids.
- Large-scale PV power plants: Contributing to grid-connected power supply for cities and industrial zones.
- Specialized scenarios: Powering marine equipment, meteorological stations, traffic signals, and portable electronic devices.