1 Functional characteristics of solar street lights
Urban street lighting is closely related to people's production and life. With the acceleration of China's urbanization process, green, efficient, environmentally friendly, long-life LED street lamps have gradually entered people's production and life; the biggest advantage of solar road lighting is that it does not need to set up transmission lines or digging trenches, laying cables, without the need for special management and control, can be conveniently installed in the city roads, squares, parks, parking lots and highways and other places. Compared with traditional lighting fixtures, ultra-high brightness LED lighting source its small size, light weight, good directionality, can withstand a variety of harsh weather conditions, in terms of power consumption, service life, as well as environmental protection and other aspects of other light sources incomparable superiority, coupled with the energy-saving efficiency of the solar energy lamps and lanterns and installation, maintenance and easy, will lead us into a new era of green lighting. Solar street light consists of solar panels, batteries, high-brightness lamps, controllers and other components, the normal operation of the moving parts are very few, basically no noise. Solar street light controller in the control circuit, its function and the function of the ordinary street light controller is basically the same, are to complete the dark light, light off the operation, the difference is that there is more than one of the battery charging and discharging management. Commonly used at home and abroad, street light controllers have a separate light controller, clock controllers and latitude and longitude type controllers and other three kinds, their working principle is different, each with its own advantages and disadvantages, is briefly discussed below.
1.1 Individual Optical Controller
Individual light control device using light-sensitive probe, when it gets dark when the light is weak, automatically turn on the street lamps; early morning when the Orient reveals the white of the fish maw, automatically turn off the street lamps, can achieve the role of automatic control. Early light control switch using discrete semiconductor components, circuit complexity, and high failure rate; with the development of semiconductor technology, the emergence of time-based integrated circuits, so that the light control switch circuit simplicity, light-sensitive probe is the key components of the light control switch.
1.2 Clock Controller
The controller should be pre-set switching time, so that the street lights on time, on time off, so as to achieve the purpose of automatic control, saving electricity. The advantage of the pre-set switching time by external light interference, in addition to its own failure, will not produce false action, the disadvantage is that according to seasonal changes and special weather conditions can not automatically change the switching time, the need to set up a person to adjust the switching time, for example: winter and spring darkness earlier, dawn later; summer and fall dawn earlier, darker; after midnight on the road vehicles, pedestrians, should be appropriately reduce the number of lights, to Before dawn and then light them up, in order to facilitate traffic safety and power saving. Timing switch in the clock controller is divided into mechanical clock type and electronic clock type two kinds: the former to quartz clock-based, accurate time, but due to the movement used in the plastic gears will be deformed at high temperatures, resulting in timing is not allowed or even shut down; the latter timing switch commonly used in the LR6818, LM8650 and other integrated blocks for the center of the electronic clock circuit, and in recent years there is also a will be an electronic clock circuit board and LED liquid crystal display integrated integrated circuit. In recent years, there is also an electronic clock circuit board and LED liquid crystal display into one integrated block, can be set up in six groups of switching points, and has a weekly function, many component manufacturers scramble to produce the product, is now mostly used in street light controllers.
1.3 Warp and Warp Controller
Longitude and latitude type controller adopts microcontroller technology, simulating the sunshine law, it can automatically turn on the light when it is dark, and automatically extinguish the light in the early morning. It adopts the advantages of light-controlled switch control time, to overcome the shortcomings of light-controlled switch by the external interference, absorbing the clock control time accurate strengths, avoiding the timing switch will not automatically change the shortcomings of the switch time. At present, many large and medium-sized city street lamps are mostly used in this way of control, the disadvantage is that the price is higher.
2 Functional characteristics of solar street light components and their applications
In the development of new energy sources, it is unanimously recognized at home and abroad that solar power generation has the highest technological content and the most promising development prospects. Solar power generation mainly has solar thermal power generation and solar photovoltaic power generation two ways. This paper focuses on solar photovoltaic power generation. Solar photovoltaic power generation is the direct conversion of solar energy into electrical power generation, can be divided into photovoltaic power generation, light induction power generation, photochemical power generation and photobiological power generation of four; currently the most widely used photovoltaic power generation, is irradiated to the solar panels on the photovoltaic effect produced by the light is directly converted into DC power output, its structure is generally composed of solar panels, storage batteries, controllers, inverters and brackets and other components. The structure is generally composed of solar panels, batteries, controllers, inverters and brackets. The disadvantages of photovoltaic power generation are: high initial investment cost; lower energy density; intermittent power generation; and greater influence by climatic conditions (no power generation on cloudy and rainy days); Photovoltaic power generation is now mainly used in three aspects, namely: providing power for places with no power supply; grid-connected power generation; and the production of solar energy electronic products such as various types of solar chargers, solar lamps and lanterns (including solar street lamps), and solar water heaters.
2.1 Basic characteristics of solar panels and their applications
In order for the solar panel module to receive as much solar radiant energy as possible in a year, an optimal tilt angle should be selected for the solar panel module during installation. The calculation of special model can get the change value of monthly average solar irradiation of different inclination planes, and the solar irradiation varies greatly in different angles of inclination planes, therefore, when installing the solar panel module, it should be selected by test to choose the suitable local inclination angle in order to get the maximum amount of solar irradiation.
2.2 Basic Characteristics of Solar Stacks and Their Applications
Solar battery pack is the energy storage device of solar panel, its role is to store the electricity issued by the panel when there is sunshine, at night or cloudy and rainy days for the load to use. Battery pack is made of a number of batteries connected in series and parallel, its capacity requires it to be able to meet the requirements of the street lamps in the absence of solar radiation in the light of the day, the power supply time and power supply needs. Currently commonly used in China is lead-acid batteries, in important occasions can also be used in cadmium-nickel batteries, but the latter price is higher. Battery storage is chemical energy, it will be converted to chemical energy DC energy stored, and then when needed to chemical energy into electrical energy release, visible energy conversion process is reversible, the former is called battery charging, the latter is called battery discharge. Therefore, in the photovoltaic power generation system, the battery plays a role in storing and regulating (releasing) the power generated by the system; as the power output of the photovoltaic power generation system varies every day, the battery can also provide relatively stable power when there is insufficient sunlight or when the photovoltaic power generation system needs to be repaired.
2.3 Basic characteristics of solar lighting fixtures and their applications
Since LED is a DC power supply device, it is easy to be made into DC lamps and lanterns, which are widely used in DC power systems, such as solar lamps and lanterns. It has flat light-type ultra-brightness LED, a single beam-type ultra-brightness LED and flat light-type and beam-type ultra-brightness LED combinations of three kinds, due to the single beam-type ultra-brightness LED light tubes produced by the light directionality is too strong, the overall visual effect is poor, therefore, should be preferred to the flat light-type ultra-brightness LED or flat light-type and beam-type ultra-brightness LED combinations, will be more than one LED centralized, arranged to form a regular LED light source as a solar street light. The combination of multiple LEDs is arranged to form a regular LED light source, which is used as the lighting fixtures of solar street lamps.
2.4 Overcharge and overdischarge protection function of solar street lamps
In the application of solar street lamps, attention should be paid to its battery overcharge and overdischarge control. The so-called overcharge control, that is, in the battery is overcharged state to timely disconnect the charging circuit, and overdischarge control, that is, in the battery is overdischarged state to timely disconnect the discharge circuit, so as to protect the battery and extend its service life. Judgment of overcharge and overdischarge is based on the high and low changes in battery voltage: when the sun shines on a sunny day, the solar photovoltaic panel absorbs light energy through the relay switch normally closed point to the battery charging, when the voltage of the battery is higher than 26V, the battery is in an overcharged state, the relay switch is normally closed point is closed, normally closed point is closed, the charging circuit is automatically disconnected to stop charging the battery to achieve the function of overcharging protection; at night, the battery supplies power to the street lamps. At night, when the battery supplies power to the street light, when the voltage of the battery is lower than 22V, the battery is in the state of over-discharge, the relay switch is turned from normally closed to normally open, the discharge circuit is automatically disconnected, and the power supply to the load (street light) is stopped, thus realizing the function of over-discharge protection.
