Solar Panel Technology Overview and Application Design

With the acceleration of the global energy transition, solar energy, as a core component of clean and renewable energy, plays a pivotal role in the energy revolution. This article systematically analyzes the value and potential of solar panels from technical principles, type variations, practical applications, and development trends.

Feb 1st,2025 112 Views

Basic Definition and Working Principles of Solar Panels

A solar panel is a semiconductor device that converts solar radiation into electricity through the photovoltaic or photochemical effect, typically composed of multiple interconnected photovoltaic cells encapsulated together.

1. Semiconductor Materials

a. Solar cells primarily use silicon as the semiconductor material.
b. Silicon is doped with elements like boron or phosphorus to form P-type (positive) and N-type (negative) semiconductors.

2. Photovoltaic Effect

a. When sunlight strikes a solar cell, photons (energy particles of light) collide with electrons in silicon atoms, freeing them from atomic nuclei.
b. Freed electrons move through the N-type semiconductor, generating an electric current.

3. PN Junction Formation

At the interface of P-type and N-type semiconductors, electron and hole migration create a potential difference, forming a PN junction.

4. Current Generation

Electrons flow from the N-type region to the P-type region, while holes move in the opposite direction, producing an electric current.

5. Voltage Output

Multiple cells are connected in series and encapsulated into a panel. When sunlight hits the panel, voltage and current are generated internally.

Components of Solar Panels

Solar panels generally consist of surface encapsulation, adhesive film, cell sheets, backsheet, and wiring.

Surface Encapsulation
Materials: Glass, PET, or ETFE.
Glass:
Advantages: High light transmittance, weather resistance, mechanical strength, chemical stability, and long lifespan.
Disadvantages: Heavy, fragile, higher cost.
ETFE (Ethylene Tetrafluoroethylene Copolymer):
Advantages: Lightweight, flexible, weather-resistant, self-cleaning, high transmittance.
Disadvantages: Lower mechanical strength, higher cost.
PET (Polyethylene Terephthalate):
Advantages: Low cost, lightweight, good processability, decent transmittance.
Disadvantages: Poor weather resistance, shorter lifespan, prone to aging.

Adhesive Film
Functions: Bonds cells to glass or backsheet, protects cells from environmental damage, and extends lifespan.
Types:
EVA (Ethylene Vinyl Acetate):
Advantages: High transparency, UV resistance, strong adhesion, mature technology, and low cost.
Disadvantages: High water permeability, PID susceptibility, and power degradation over time.
POE (Polyolefin Elastomer):
Advantages: Superior moisture resistance, anti-PID performance, ideal for high-efficiency components like double-glass or N-type cells.
Disadvantages: Higher cost, processing challenges (e.g., slippage, bubbles), weaker glass adhesion than EVA.

Cell Sheets
The core component generates electricity. Types include:
Monocrystalline Silicon Cells:
Made from high-purity monocrystalline silicon.
Advantages: High conversion efficiency (≥20%), stability, long lifespan.
Disadvantages: Higher cost.
Polycrystalline Silicon Cells:
Made from polycrystalline silicon.
Advantages: Lower cost, simpler manufacturing.
Disadvantages: Lower efficiency (15–20%).

Thin-Film Cells
Include amorphous silicon, CIGS (Copper Indium Gallium Selenide), and CdTe (Cadmium Telluride).
Advantages: Lightweight, flexible, scalable production.
Disadvantages: Lower efficiency (10–15%), stability issues.
Manufacturers: SunPower, LONGi, Huanghe Hydropower, JinkoSolar.

Backsheet
Small panels: Typically use PCB boards for cell interconnection.
Large panels: Use conductive tapes or copper strips.

Performance Metrics

Conversion Efficiency: Ratio of solar energy converted to electricity. Monocrystalline: >20%; Polycrystalline: 15–20%; Thin-film: 10–15%.
Maximum Power (Pmax): Output under standard conditions (1000 W/m², 25°C, AM1.5 spectrum).
Open-Circuit Voltage (Voc): Voltage when not connected to a load.
Short-Circuit Current (Isc): Current when terminals are directly connected.
Operating Voltage/Current: Values at maximum power output.

Solar Panel Design

1. Area & Power Calculation

Formula:

A = \frac{P}{η \times G}

- - $A$ : Area (m²)
  - $P$ : Rated power (W)
  - $η$ : Efficiency (decimal)
  - $G$ : Solar irradiance (W/m²; 1000 W/m² under standard testing).
- Example: A 1W panel with 20% efficiency requires $A = 1 / (0.2 \times 1000) = 0.005 m²$ (e.g., 10 cm × 5 cm)

2. Voltage Configuration

- Single cell voltage: ~0.55V (rated), 0.65–0.7V (open-circuit).
- Series-parallel arrangement: For a 5V system, connect 9–10 cells in series, then parallel for higher current.

Monocrystalline, Polycrystalline, and Thin-Film Solar Panels: Key Differences, Costs, and Efficiency Ratings

What are solar panels and what are the advantages of using solar panels？

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