Analysis on the development of off-grid inverters in the photovoltaic industry

In today’s life, solar energy products can be seen everywhere. People use solar energy to cook rice, and solar water heaters, etc., and solar energy products are everywhere. Of course, the most important thing is solar power generation, but the current technology does not allow people to make good use of it. solar energy generation.

In today’s life, solar energy products can be seen everywhere. People use solar energy to cook rice, and solar water heaters, etc., and solar energy products are everywhere. Of course, the most important thing is solar power generation, but the current technology does not allow people to make good use of it. solar energy generation.

Driven by the background of the gradual improvement of the industrial chain, the production cost of photovoltaic cells in China has continued to decline. The diamond wire cutting technology has been fully popularized in the field of single polysilicon. The use of this technology improves the production and thinning efficiency of silicon wafers, and the thinning of silicon wafers is an important boost to reduce the cost of batteries, so the wide-scale application of the technology can directly reduce the Photovoltaic cell production costs. Using diamond wire to cut monocrystalline silicon wafers, according to the thickness of 190um, the cost can be reduced by about 0.15 yuan per piece for every 10um reduction in the diameter of the diamond wire, the production capacity can be increased by 4%, and the cost can be greatly reduced. On the other hand, since the grid parity has not yet been achieved, the price of photovoltaic products has further decreased, prompting photovoltaic cell manufacturers to continue to reduce costs. Under the influence of the market force mechanism, upstream manufacturers in China’s photovoltaic industry are reducing raw material production costs by expanding production scale, improving product conversion efficiency and reducing consumables costs. As far as the development of the photovoltaic industry is concerned, the improvement of the industrial chain and the market force mechanism will further promote the development of the photovoltaic manufacturing industry.

In a photovoltaic grid-connected system, components, inverters, and power grids constitute an electrical system. The solar radiation of the solar module will be converted into solar energy, and the Inverter will generate as much power. Therefore, the grid-connected inverter has no special requirements for AC overload, because the output power of the inverter will basically not exceed the power of the module. In a photovoltaic off-grid system, components, batteries, inverters, and loads form an electrical system. The output power of the inverter is determined by the load. Some inductive loads, such as air conditioners, water pumps, etc., inside the motor, the starting power It is 3-5 times the rated power, so the off-grid inverter has special requirements for overload.

Loads are classified into resistive loads, inductive loads, and capacitive loads according to their impedance properties. Resistive load: A load with no phase difference between current and voltage is a resistive load, such as rice cookers, light bulbs, electric stoves, electric soldering irons, etc. Inductive load: The load when the current lags the voltage by a phase difference is an inductive load, such as washing machines, air conditioners, refrigerators, water pumps, range hoods and other loads with motors and transformers, relays, compressors, etc. Capacitive load: A load with a negative phase difference of current ahead of voltage is a capacitive load, such as compensation capacitors, computers, TVs, etc., which are used in switching power supplies at home. The starting power of inductive loads such as motors is 5-7 times of the rated power. When calculating the power of the inverter, the starting power of these loads should be taken into account.

The off-grid inverter with high-frequency isolation technology can achieve twice the peak power of the rated power; the off-grid inverter with power frequency isolation technology can reach three times the rated power. Then, a 3kW high-frequency off-grid inverter can drive a 1P air conditioner (starting power is about 5.5kVA), and a 12kW power frequency off-grid inverter can drive a 6P air conditioner (starting power is about 5.5kVA). The power is about 33kVA). The inverter provides starting energy to the load, and part of it comes from the battery or photovoltaic modules, and the excess part is also provided by the inverter itself (internal energy storage components – capacitors and inductors).

The waveform of the inverter is mainly divided into two categories, one is a sine wave inverter, and the other is a modified wave inverter. The modified sine wave inverter uses the PWM pulse width modulation method to generate the modified wave output. Due to the harmonic distortion of about 20%, it cannot carry inductive loads such as air conditioners, but can carry resistive loads such as lamps. The modified sine wave inverter adopts non-isolated coupling circuit, the device is simple and the efficiency is high. The pure sine wave inverter is designed with an isolated coupling circuit, which is complicated and expensive. It can be connected to any common electrical equipment (including TVs, LCD monitors, etc., especially inductive loads such as refrigerators) without interference.

Although solar energy can generate a lot of energy, the current technology is not enough to ensure all the operations of human beings, which requires us to protect energy, start from ourselves, start from the little things around us, and save energy is what every human being should do. responsibility.

The Links:   SEMIX604GB176HDS NL128102BC29-10C