The application of solar technology in lighting!

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 cell modules, batteries, controllers, inverters, lighting loads, and the like. When the lighting load is DC, the inverter is not used.

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 Because 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 The controller controller's role is to make solar cells and batteries work safely and reliably to achieve maximum efficiency and extend 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 solutions The application of solar photovoltaic technology is not only important in remote areas and temporarily power-deficient areas, but also rapidly spread 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 Urban 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."

2.1 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 night is automatically switched on. When the information is detected, 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, which reflects the humanized design concept while reducing various expenses. 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 "photovoltaic - architectural 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.

3 solar lighting equipment

Solar lighting equipment is mainly composed of lighting fixtures, light sources and control systems. Solar lighting fixtures mainly include solar lawn lights, garden lights, landscape lights and high pole lights. These lamps are powered by sunlight, charged during the day and used at night, eliminating the need for complex and expensive pipelines, and the layout of the fixtures can be arbitrarily adjusted. The light source generally adopts LED or DC energy-saving lamps, has a long service life and is a cold light source, and is harmless to plant growth. The solar lighting fixture is an automatically controlled working system that automatically works as long as the operating mode of the system is set. The control mode is generally divided into a light control mode and a timing control mode, and generally adopts a light control or a combination of light control and timing. When the light intensity is lower than the set value, the controller start light is on and the timing starts. When the time is up to the set time, it stops working. The charging and switching process can be intelligently controlled by the microcomputer, automatic switch, no manual operation, stable and reliable work, saving electricity and maintenance. Among them, the design of solar landscape lights is mostly made of metal and engineering plastics combined with die-casting. The lamp body can be round, square, geometric and other shapes, with thousands of styles, different styles, luxurious and elegant, or simple and clear. The color of the lamp body is white, red, green, blue, purple, yellow, etc., which are gradually changed or flashed. After dark, the system automatically starts the lighting device. At first glance, the lamp body emits even and soft light, and several colors jump and change. The night of the whole city is rhythm in a flash. The solar high pole lamp generally has a height of 8 to 13 meters, an illumination power of 50W to 130W, and an effective illumination area of ​​several hundred square meters. As night falls, neon flashes, brilliance, and extraordinarily enchanting.

4 Solar lighting cost analysis

In recent years, the production capacity of solar cells in China has soared, and the price of its products has dropped from 80 yuan/watt in the early days of the "seventh five-year plan" to below 40 yuan/watt. The price bottleneck that promotes the use of solar photovoltaic application products has been basically solved, and the promotion of its products is no longer restricted by the high price of solar photovoltaic products, making it impossible to become popular. It is expected that by the 1920s and 1930s, the cost of solar power generation may be reduced to the level of conventional electricity prices.

The solar lighting project can save a lot of money every year. It not only brightens the city, but also develops the city ecologically and makes full use of energy. It is the most reasonable development direction in the world.

Take the solar staircase walkway lamp of a 20-story high-rise residential building as an example: the one-time cost is about 10 yuan per square meter, and the service life is about 15 years. Compared with the emergency light with its own battery, the one-time cost is almost the same. Solar lighting has a longer life and saves on electricity bills. Take the solar garden lamp as an example: every 3,000-4,000 yuan, about twice as expensive as ordinary garden lights, but if you count the investment in electrical pipelines and distribution facilities plus 3 to 5 years of electricity and daily maintenance fees, The cost is also basically the same.

5 Problems with solar lighting

5. 1 Efficiency of solar photovoltaic systems

The overall efficiency of a solar photovoltaic system consists of the PV conversion rate of the battery components, controller efficiency, battery efficiency, inverter efficiency, and load efficiency. At present, the conversion rate of solar cells is only about 17%, and the efficiency of controllers, batteries, and inverters is much higher than this. For example, the efficiency of inverters has reached more than 95%. Therefore, improving the conversion rate of battery components and reducing the unit cost are the key and difficult points of solar power industrialization.

5. 2 Solar cell capacity

At present, solar cells are still difficult to use on main road lighting. The lighting of the main roads of the highway has higher illumination requirements. In terms of the current conversion efficiency and price of solar cells, this requirement cannot be met. But in the near future, with the improvement of technology level, the application of solar lighting on the main roads of highways will be popularized.

5. 3 solar energy storage components

The service life of solar cells is more than 25 years, and the service life of ordinary batteries is 2 to 3 years, so the battery is the weakest link in the solar power system. The storage capacitor can solve this problem to some extent. The life of the storage capacitor can be more than 10 years, and the control circuit is simple, but the expensive price limits its application. Currently it is only applied to some traffic lights and decorative lights. With the development of technology and economy, it will be the most promising energy storage component for solar cells.

5. 4 Quality of solar energy products

In recent years, solar photovoltaic technology has developed rapidly, and product manufacturers have sprung up. However, some products do not form a series, the quality is uneven, and even there are many defects in the choice of light source and circuit design, which reduces the economy and reliability of the product. At the same time, the country lacks corresponding product quality standards and testing systems, which has affected the industrialization of solar photovoltaic technology.