Yang Weijie
(China University of Mining and Technology, Xuzhou 221008, China)
Abstract ï€ ï€ ï€ To ï€ : ï€ ï€ outlines the principle and system of solar photovoltaic technology constitutes, introduced the application of solar photovoltaic technology in the lighting project and its costs and problems to do a brief analysis.
Keywords: solar photovoltaic technology lighting scheme lighting equipment
With the development of the economy and the progress of society, people have put forward higher and higher requirements for energy. Finding new energy sources has become an urgent issue facing humanity. Solar power is considered to be the most important energy source in the 21st century because it has the advantages of cleanliness, safety, resources, and sufficiency that cannot be compared with thermal power, hydropower, and nuclear power. At present, solar energy application technology has made great breakthroughs, and has been more maturely applied to building corridor lighting, urban lighting, solar hot water supply and heating systems. In particular, the development of solar photovoltaic technology has brought a broader prospect to the application of solar energy in lighting.
1 Solar photovoltaic technology
Solar photovoltaic technology is a technology that uses solar modules to directly convert solar energy into electrical energy. Solar photovoltaic systems mainly include: solar modules, batteries, controllers, inverters, lighting loads, etc. (see Figure 1). When the lighting load is DC, the inverter is not used (see Figure 2).
1.1 Solar cell
A solar cell module is a solid device that utilizes the electronic properties of a semiconductor material to effect PV conversion. The solar modules used in solar lighting fixtures are composed of a plurality of solar cells connected in parallel, because the power generation of a single battery is very limited due to current technology and materials. A commonly used single cell is a silicon crystal diode. When sunlight is applied to a PN junction composed of two types of homogeneous semiconductor materials of different conductivity types, P-type and N-type, under certain conditions, solar radiation is semiconductor material. Absorbed to form a built-in electrostatic field. In theory, at this time, if the electrodes are drawn on both sides of the built-in electric field and connected to an appropriate load , a current is formed. In recent years, the development of amorphous silicon solar cells has also made greater progress. Due to its advantages of low production cost, simple process, and saving raw materials, it will occupy an important position in the future photovoltaic technology. The output power of the solar cells is random, and the output power of the same solar cell is different at different times and at different locations. The peak power Pm of a solar cell is determined by the local average solar radiation intensity and the end electrical load.
1.2 Battery
Since the input energy of the solar photovoltaic system is extremely unstable, it is generally necessary to configure the battery system to work. The direct current generated by the solar cell first enters the storage of the battery and reaches a certain threshold to supply the lighting load. The characteristics of the battery directly affect the efficiency, reliability and price of the system. The choice of battery capacity generally follows the following principles: First, the energy of the solar module during the day is stored as much as possible while meeting the night illumination, and at the same time, it is necessary to store the energy required for the illumination of the predetermined continuous rainy night.
1.3 Controller
The role of the controller is to make solar cells and batteries work safely and reliably for maximum efficiency and long battery life. The charge and discharge conditions are limited by the controller to prevent reverse charging, overcharging, and overdischarging of the battery. In addition, it should also have the functions of circuit short circuit protection, reverse connection protection, lightning protection and temperature compensation. Since the output energy of the solar cell is extremely unstable, the quality of the charge and discharge control circuit is critical for the design of the solar luminaire.
1.4 DC-AC converter
The main function of the inverter is to convert the DC power of the battery into AC power. The inverter circuit is modulated, filtered, boosted, etc., and the sinusoidal AC power supply matching the rated frequency and rated voltage of the lighting load is used by the end user of the system. The inverter should also have functions such as short circuit protection, under voltage protection, over current protection, reverse connection protection and lightning protection.
2. Solar lighting solution
The application of solar photovoltaic technology not only has a very important position in remote areas and temporarily power-deficient areas, but has also been rapidly popularized in other areas, and has been applied in various industries such as transportation, construction, agriculture and forestry. Especially in the lighting project, it is even more colorful.
2.1 city ​​lighting
At present, the application of solar photovoltaic technology in urban lighting has been started and gradually applied by the rapid development momentum. Solar photovoltaic lighting technology can be used for signs, warning signs, lawn lights, street lamps, etc. in schools, parks, residential quarters, villas, etc., making public lighting more convenient, safe, environmentally friendly and energy efficient. The working principle of solar lighting is: the solar panel is used as the power generation system, and the battery power supply is charged by the high-power diode and the control system. When the battery power reaches a certain level, the automatic protection system in the control system operates. The panel automatically cuts off the power and implements automatic protection. In the evening, the solar panel plays a role of light control, and gives instructions to the control system. At this time, the control system automatically turns on and outputs voltage, so that all kinds of lamps reach the designed lighting effect. The required lighting time can be adjusted.
Solar lighting lighting technology has the characteristics of one-time investment, no long-term operation cost, convenient installation, maintenance-free, long service life, etc. It will not cause damage to the original vegetation and environment, but also reduce various expenses and save energy. "Get more in one fell swoop."
2.2 Building corridor lighting
   Solar corridor lights are powered by solar panels. The whole building adopts the overall layout, split installation and centralized power supply. The solar energy is installed on the roof or roof and is transported to each walkway and stairway with dedicated wires (reservable). The system uses sound, light sensing, and delay control. During the day, the system is charged and the nighttime automatic conversion is turned on. When a person walks around the information, the lighting device is automatically activated, and the time is turned off after 3 to 5 minutes. When there is a sudden accident such as a fire or an earthquake in the building, the power supply can be continuously powered for 3 to 5 hours. It can be used as an emergency light. It reduces the cost and embodies the humanized design concept. This kind of product can also be used in the building number plate, unit door and other parts of the community, providing convenience for night returnees and visiting guests.
   Solar corridor lights are powered by solar panels. The whole building adopts the overall layout, split installation and centralized power supply. The solar energy is installed on the roof or roof and is transported to each walkway and stairway with dedicated wires (reservable). The system uses sound, light sensing, and delay control. During the day, the system is charged and the nighttime automatic conversion is turned on. When a person walks around the information, the lighting device is automatically activated, and the time is turned off after 3 to 5 minutes. When there is a sudden accident such as a fire or an earthquake in the building, the power supply can be continuously powered for 3 to 5 hours. It can be used as an emergency light. It reduces the cost and embodies the humanized design concept. This kind of product can also be used in the building number plate, unit door and other parts of the community, providing convenience for night returnees and visiting guests.
2.3 " Photovoltaic - architectural lighting integration " technology.
Solar modules and building components have been successfully integrated, such as solar roofs ( tops ) , walls and doors and windows, to achieve " PV - Building Lighting Integration (BIPV)" . The working principle of the system is: a panel composed of a plurality of monocrystalline silicon solar photovoltaic cells, which emits a direct current after being irradiated by sunlight, and then converts the direct current into a general electrical appliance by a power converter in the system. The required AC power is used by lighting, air conditioning and other systems through the power distribution system, and the battery storage power can provide emergency power demand for disaster prevention. The shape, color, architectural style and building of the PV modules on the walls and roof of the building are integrated with the surrounding natural environment for perfect coordination. An aluminum panel curtain wall manufacturing company in China has successfully developed a " sun room " , which combines power generation, energy conservation, environmental protection and value-added into one room. It successfully combines optoelectronic technology with building technology, called Solar Building System (SPBS) , which has passed Expert argumentation. This will effectively promote the industrialization and marketization of solar energy building energy conservation.