Talking about the composition of off-grid photovoltaic power generation system solar street light-litelsolar production

The off-grid photovoltaic power generation system is mainly composed of solar photovoltaic power generation device, energy storage device, controller and inverter. Each part is briefly introduced below. Solar photovoltaic power generation devices can be composed of monocrystalline silicon or polycrystalline silicon or amorphous silicon photovoltaic devices. A group of solar cells encapsulated with glass and special materials is called a solar cell module; multiple solar cell modules are connected to form a solar cell array. The type and composition of solar cells are selected according to the power required by the system, the use environment, and the cost. Since photovoltaic power generation is directly affected by weather conditions, the energy storage device is intermittent and unstable. In order to maintain a certain continuous power supply capability of the system, there must be an energy storage device to store part of the electrical energy and provide electrical energy when there is no sunlight. At present, photovoltaic power generation systems mainly use batteries for energy storage. Commonly used batteries are lead-acid batteries, nickel-cadmium batteries, lithium-ion batteries, etc. Lead-acid battery: single-cell voltage 2 volts, cycle life 500-1500 times NiCd battery: single-cell voltage 1.0-1.3 volts, cycle life 2500 times Li-ion battery (single battery voltage 3.7 volts), cycle life 1000- 10,000-cycle nickel-cadmium batteries and lithium-ion batteries are expensive, but have large capacity per unit volume, and are mostly used in applications that require small size and large capacity, such as mobile phones, cameras, portable computers and other digital products. Generally, off-grid photovoltaic systems mainly use sealed lead-acid batteries. Lead-acid batteries are very cheap, sealed lead-acid batteries are sealed and maintenance-free, and are very convenient to use. The main parameters of a battery are voltage, capacity, and cycle life. The unit of voltage is volts (V), the unit of capacity is ampere-hour (Ah), and the cycle life is the number of times of charge and discharge. The battery of the controller has certain requirements for charging and discharging. Frequent overcharging and overdischarging will reduce the service life. It is necessary to control the charging and discharging of the battery, which is the primary function of the controller. Select the maximum power operating point of the solar cell according to the user's electricity consumption, battery charge and discharge, and the solar cell's light condition, and coordinate charging and electricity current. The controller also needs to detect, protect and display data to the system. The controller mainly uses the DC-DC conversion circuit to convert the voltage and current. For the DC-DC conversion principle, see the 'DC-DC Converter Principle' section. The inverter is a device that converts DC power into AC power, mainly using SPWM full-bridge inverter circuit to generate sine wave AC power. For the principle of SPWM inverter, see the section 'Principle of SPWM Inverter'. Electrical equipment that uses direct current or alternating current for electrical loads. Simple solar photovoltaic power generation devices do not have inverters and only output direct current, some of which can output several different direct current voltages, as shown in Figure 2. The controller accepts the DC power output by the solar panel, and controls the charging or discharging current of the battery. The simple controller directly leads the battery to the output end, and the system output voltage is equal to the battery voltage. Some controllers have DC conversion circuits, which can output several different DC voltages, such as 5V, 9V, 12V, etc., suitable for different electrical appliances. The output power of this kind of system is generally small, and the portable structure is mostly used.