Solar panels are devices that absorb sunlight and convert solar radiation energy directly or indirectly into electrical energy through the photoelectric effect or photochemical effect. The main material of most solar panels is silicon. When sunlight shines on the surface of a solar cell, some photons are absorbed by the silicon material; the energy of the photons is transferred to silicon atoms, causing electrons to jump and become free electrons. These free electrons accumulate on both sides of the PN junction, creating a potential difference. When an external circuit is connected, under the influence of this voltage, a current will flow through the external circuit, generating a certain output power. Essentially, this process is the conversion of photon energy into electrical energy.
Solar panel power calculation
A solar AC power generation system consists of solar panels, a charge controller, an inverter, and a battery; a solar DC power generation system does not include an inverter. To ensure the solar power system provides sufficient power to the load, the components must be selected appropriately based on the power consumption of the appliances. The following example, using a 100W output power system and 6 hours of daily use, illustrates the calculation method:
1. First, the daily watt-hours consumed (including inverter losses) should be calculated: If the inverter's conversion efficiency is 90%, then when the output power is 100W, the actual required output power should be 100W/90%=111W; if it is used for 5 hours a day, the output power is 111W*5 hours=555Wh.
2. Calculation of solar panel output: Assuming 6 hours of effective sunshine per day, and considering charging efficiency and losses during charging, the output power of the solar panel should be 555Wh/6h/70% = 130W. Here, 70% represents the actual power used by the solar panel during charging.
Solar panel power generation efficiency
Monocrystalline silicon solar cells boast a photoelectric conversion efficiency of up to 24%, the highest among all types of solar cells. However, their high manufacturing cost limits their widespread adoption. Polycrystalline silicon solar cells are cheaper to manufacture than monocrystalline silicon cells, but their photoelectric conversion efficiency is significantly lower, and their lifespan is also shorter. Therefore, in terms of performance-price ratio, monocrystalline silicon solar cells are slightly better.
Researchers have discovered that some compound semiconductor materials are suitable for use as thin films for solar photovoltaic conversion. Examples include CdS, CdTe, and III-V compound semiconductors such as GaAs and AiPInP. Thin-film solar cells made with these semiconductors exhibit excellent photoelectric conversion efficiency. Multi-component semiconductor materials with gradient band gaps can broaden the solar absorption spectrum, thereby improving photoelectric conversion efficiency. This makes the widespread practical application of thin-film solar cells a promising prospect. Among these multi-component semiconductor materials, Cu(In,Ga)Se2 is a high-performance solar absorber. Based on it, thin-film solar cells with significantly higher photoelectric conversion efficiency than silicon can be designed, achieving a conversion efficiency of 18%.
Lifespan of solar panels
The lifespan of a solar panel is determined by the materials used in its cells, tempered glass, EVA, TPT, etc. Panels made by manufacturers using higher-quality materials can typically last up to 25 years. However, due to environmental factors, the materials in solar panels will age over time. Generally, the power output will decrease by 30% after 20 years and by 70% after 25 years.
