2. The surface area of a solar cell is 100 cm2. When the light intensity shining on the cell surface is 1 kW/m', the operating temperature is 300 K, the open circuit voltage of the battery is 600 mV and the short circuit. The circuit current is 3.3A. Assume the battery is operating normally, calculate the conversion efficiency at the maximum power point.
How does temperature change impact solar cells?
The absorption spectrum is indeed an important factor. Aerospace solar panels are made from a combination of materials, not just silicon. Each material has its own corresponding absorption spectrum, which maximizes the use of sunlight. But the cost is too high. Cost is therefore also an important factor. Manufacturers must weigh cost and effectiveness. The first is the band gap of the materialu. Each photon absorbed by the battery, whatever its energy, can only produce one electron-hole pair. This phenomenon can limit battery efficiency. Another reason is that the output voltage can only account for part of the bandgap potential difference, which for silicon is about 60%. There is also the influence of temperature. The open circuit voltage and battery fill factor decrease as temperature increases. The lifespan of carriers is an important influencing factor. As for optical losses, one is surface reflection and obstruction by the metal grid, and the other is that photons can pass directly through the battery. The light-absorbing material for perovskite solar cells typically uses lead or nickel halides, so named because their crystal structure is similar to that of perovskite. This type of light-absorbing material has excellent photoelectric properties and low manufacturing cost, and has become a research hot spot in the field of solar power generation in recent years. The Ulsan National Institute of Science and Technology in South Korea issued a press release stating that the new method was jointly developed by the institution, the Korea Institute of Chemical Technology and Hanyang University. The key is to reduce structural defects in light-absorbing materials. Tiny defects in the crystal structure of lead or nickel halides prevent the conversion of light energy into electricity and are a key factor limiting the conversion efficiency of perovskite solar cells. In addition, when the diffusion length of the minority carriers is equivalent to or greater than the thickness of the silicon wafer, the speed of recombination on the back surface also has a significant impact on the characteristics of solar cells. The researchers added additional iodine ions to the organic cation solution used as raw material to create a light-absorbing material with fewer crystal structure defects.
Temperature factors also affect the performance of solar cells. As the temperature increases, the open circuit voltage decreases linearly. Solar cells made of different materials have their own operating temperature ranges. For a certain solar cell, at different temperatures, the optimal load required to obtain the maximum power output is also different. Effects of Light Intensity and Temperature on Solar Cells Light intensity and temperature are two factors that also affect voltage and temperature characteristics.current from solar cells. When the light intensity is 200 W/m2: the open circuit voltage is 0.5 V and the short circuit current density is 5.2 mA/cm2. When the light intensity is 400 W/m2: the open circuit voltage is 0.55 V and the short circuit current density is 13 mA/cm2. When the light intensity is 600W/m2: the open circuit voltage is 0.57V and the short circuit current density is 17 mA/cm2. Previous groupThe data gives the dependence of the open circuit voltage and short circuit current density of silicon solar cells on the intensity of sunlight. Therefore, solar cells can achieve higher power output under stronger light. But the required load resistance at maximum output power is also different. Temperature factors also affect the performance of solar cells. When the ttemperature increases, the open circuit voltage decreases linearly. Solar cells made of different materials have their own operating temperature ranges. For a certain solar cell, at different temperatures, the optimal load required to obtain the maximum power output is also different. Solar cells do not convert all types of light into electricity in the same way. For example: Usually, the ratio of red light converted to electricity is different from the ratio of blue light converted to electricity. Since the color (wavelength) of light is different, the proportion of light converted to electricity is also different. This characteristic is called spectral characteristics. Spectral characteristics are usually expressed in terms of collection efficiency; collection efficiency is a percentage (%) used to express the numberre of electrons (and holes) generated when a unit of light (a photon) arrives on a solar cell. . Generally speaking, the number of electrons (and holes) generated by a photon is less than 1. Measuring spectral characteristics is to illuminate the solar cell with a certain intensity of monochromatic light, measure the short circuit current of the battery at this time, then change the wavelength of the monochromatic light in sequence, and then repeat the measurement to obtain the short circuit current at each wavelength, which reflects the spectral characteristics of the battery .