Solar water heaters generally consist of three parts: a water tank, a collection tube and a bracket
Solar energy resources. Solar energy is the most important source of energy on Earth. However, most of its energy cannot reach the surface via Earth's atmosphere. How to maximize the use of solar energy is a scientific research topic for scientists.
The most abundant energy in the universe is inexhaustible solar energy. Space solar power plants are designed to maximize the use of solar energy. The large object at the top left of the image is a device that converts solar energy directly into electrical energy. This device is generally made by infiltrating a thin layer of boron onto a small piece of N-type silicon single crystal by diffusion method to obtain a PN junction, then adding electrodes. When the lightWhen the sun directly hits the thin layer of electrodes, an electromotive force is generated between the two poles. There are two basic methods of producing solar energy. One is photoelectric transfer, which converts sunlight directly into electrical energy, called "photovoltaic power generation", the other is to collect solar energy to generate high temperature, and then convert the energy thermal into electricity; The energy, called “thermal power generation,” produces electricity. At present, the most widely used device for "photovoltaic power generation" is "solar panels". This type of "solar panels" has been widely used on space objects such as artificial satellites.
Solar energy has "infinite reserves", universality of existence, cleanliness of development and of use, and economy gradually revealed, etc. Its developmentOpportunity and its use are an effective way to ultimately solve the problems of energy shortage, environmental pollution and greenhouse effect caused by conventional energy, especially fossil energy. Path is an ideal alternative energy source for humanity. Currently, the technology of development and utilization of solar energy, as well as its promotion and application, are advancing by leaps and bounds. In 1997, global sales of solar cells increased by 40%, becoming the fastest growing energy source in the world. Solar water heaters have formed an industry and are making a steady impact on the gas and electric water heater markets with their excellent performance-to-price ratio; solar thermal power plants have also been commercialized and represent the hope for the development of solar photovoltaic technology; faster, which is reflected in the efficiency ofphotoelectric conversion. The continued improvement in photovoltaic cell manufacturing costs and the advent of various new solar cells.
Solar power generation has enormous potential, and the solar cell industry will achieve great progress.
In the solar power generation system, the most technically complex component should be the solar cell. It can be said that solar cells are the core of solar power generation systems, and their development and production directly affect the popularity and development of solar power generation.
The main principle of solar cells is to use semiconductor materials, placing a thinner N-type semiconductor on top of a thicker P-type semiconductor. When photons strike the surface of the device, the P type and the N-. semiconductor type Electrons diffuse on the surface of the joint pto generate current, and the metal conductors at the upper and lower ends can be used to extract current.
Diagram of working principle of solar water heater 1. Cold water enters the solar water heater through the pipe, passes through the heat collecting plate and the heat collecting plate can collect solar energy, convert solar energy into thermal energy. energy, then heat the cold water. Since the density of cold water is higher than that of hot water, the hot water will automatically increase, then form circulating power, the water will gradually heat up on the heat collecting plate until 'it reaches a certain temperature. After reaching the temperature, you can enter the hot water storage tank, and hot water can be supplied when hot water is needed. Heating Figure 2. In fact, the principle of heating-Solar water mainly includes the following two principles: (1) The principle of water circulation, that is, the water flows automatically. This is based on the fact that cold water is denser than hot water. Cold water flows and hot water rises, forming natural convection that gradually heats the water in the water tank until it reaches the set water temperature. When the intensity of the sun is not sufficient to meet circulation needs, a water pump can be added to the closed water circulation circuit to obtain forced circulation. (2) Collector heat absorption principle: There is a special coating on the collector surface of the solar water heater. This coating has a high absorption rate in the visible range of solar energy. After absorbing it in the form of heat, heat. the radiation from the collector will have the wavelength in the long wave rangeand the coating has low long-wave emissivity, thereby effectively retaining solar heat. This heat is then used to gradually heat the cold water into hot water. Solar collector tube Let's talk in detail about the collector tube on this collector. The collector tube is actually like an elongated hot water kettle liner. It is made of two glass tubes, one large and one small. the inner layer is covered with a spectrum-selective absorption coating, and a straight void is drawn between the inner and outer tubes. It forms the core of the solar water heater and is used to maximize the absorption of thermal energy after solar radiation. The vacuum glass tube is round, has the characteristics of naturally following the broad source of the sun, coupled with the reflection principle of the reflector, the glass tube can receive light from all sides, the heat collection effect lasts longer, the tempwater temperature is higher. , and it can work normally all year round, even in alpine areas.