Solar System

Working principle of inverter in solar power generation system ?

The above is a relatively easy to make inverter circuit diagram, can be 12V dc power supply voltage inverter to 220V municipal voltage, the circuit by BG2 and BG3 composed of a multivibrator, and then through BG1 and BG2 drive, to control the work of BG6 and BG7.Among them, the oscillating circuit is supplied by the regulated voltage supply of BG5 and DW group, which can make the output frequency more stable.In the production, the transformer can be selected to have a commonly used dual 12V output transformer.According to the need, choose the appropriate 12V battery capacity.The following is an electrical diagram of an efficient sinusoidal inverter, which is powered by a 12V battery.First, a double voltage module is used to power the operational amplifier.ICL7660 or MAX1044 can be selected.Operational amplifier 1 generates a 50Hz sine wave as the reference signal.Op amp 2 ACTS as a phase inverter.Op amp 3 and op amp 4 act as hysteresis comparators.In fact, operational amplifier 3 and switch tube 1 constitute a proportional switching power supply.The same goes for op amp 4 and switch 2.It has an unstable switching frequency.When the output signal of op amp 1 is positive phase, op amp 3 and switch tube work.In this case, op amp 2 outputs the negative phase.At this time, the positive input potential of operational amplifier 4 (always 0) is always higher than the negative input potential, so the output of operational amplifier 4 is always 1, and the switch tube is closed.When the output of op amp 1 is negative, the opposite is true.This allows the two switches to work alternately.When the benchmark signal is slightly higher than the detection signal, that is, when the signal at the negative input end of op amp 3 or 4 is slightly higher than the signal at the positive input end, the comparator outputs 0, the switch tube is opened, and the detection signal is rapidly improved. When the detection signal is slightly higher than the benchmark signal, the comparator outputs 1, and the switch tube is closed.Note here that the comparator has a positive feedback process when the circuit is flipped, which is the characteristic of the hysteresis comparator.For example, under the premise that the benchmark signal is lower than the detection signal, the benchmark signal is immediately higher than the detection signal at the moment when they are equal, as their differences get closer and closer.This "certain value" affects the switching frequency.The bigger it is, the lower the frequency.Let's call it 0.1~ 0.2v.The purpose of C3 and C4 is to allow the continuous current of the switch with higher frequency to pass through, and generate a large impedance to the signal with lower frequency of 50Hz.C5 is calculated from formula: 50=.L is generally 70H, it is best to measure it when making.So C is going to be 0.15.The ratio of R4 to R3 should be strictly equal to 0.5, the larger the waveform distortion is obvious, the smaller can not vibrate, but would rather be larger, not smaller.The maximum current of the switch tube is: I==25A.There are two kinds of inverter, square wave output and sine wave output.Square wave output inverter high efficiency, for the use of sine wave power supply design of electrical appliances, except for a few electrical appliances are not applicable to most of the electrical appliances are applicable, sine wave output inverter is not this aspect of the shortcomings, but there is low efficiency of the shortcomings, how to choose this need according to their own needs.

What is the difference between sinusoidal inverter and ordinary inverter?

Advantages of sine wave inverter As a result of the sine wave inverter output waveform, between the maximum from positive to negative maximum value will have a little time, so use effect will be better, alternating current (ac) can provide high quality, but also can bring various kinds of load, can satisfy all kinds of electricity demand in daily life, and the efficiency is very high, so the inverter has now become the market mainstream products, but its technical requirements and the cost is relatively high. Disadvantages of square wave inverters The output is a lower quality of the square wave alternating current, its positive most roughly to the negative maximum value is almost together, so that the load and the inverter itself caused severe instability.In addition, the load capacity of the square wave inverter is very weak, accounting for only 40%-60% of the rated load. It cannot load the inductive load, otherwise it will cause the power filter capacitor in the load.

What are the protection modes of the solar controller?

Direct charge protection point voltage, this protection mode is also called urgent charge.Different from the usual protection mode, this protection mode belongs to quick charging.If the battery of the solar controller is in a state of low voltage, and it is unable to achieve the power conversion with a higher voltage, then the controller will automatically start this direct charging protection point voltage, to charge its own battery.It works mainly because it has a parameter value called a control point.Is the value in the above table, when the controller is in the process of charging, the voltage value shown is higher than the protection value, when the controller will automatically start this mode, to timely control the battery terminal voltage is lower than the protection point, to avoid the phenomenon of overcharging.Voltage at the equal-charge control point is another common protection method for solar controllers.Unlike the former, when after the direct charge controller, the controller inside the battery will be leave for a period of time, and then let the machine transformation of internal battery voltage to a natural value, after a period of time when the battery voltage drops to the recovery voltage value, the controller will enter all charge state at this time.What is equalizing?Believe that many people will be confused.It is also known as "balanced charging".Generally divided into two stages, but the time should not be too long.

How do pv modules affect rooftop pv generation?

1.Dust effect of componentsFor the long-term operation of photovoltaic power system, the impact of dust accumulation on the panel can not be underestimated.The dust on the surface of the panel has the function of reflection, scattering and absorption of solar radiation, which can reduce the solar transmittance, resulting in the solar radiation received by the panel is reduced, the output power is also reduced, and its effect is proportional to the cumulative thickness of dust.(1)temperature influenceAt present, photovoltaic power stations mostly use silicon solar cell modules, which are very sensitive to temperature. With the accumulation of dust on the surface of the modules, the heat transfer resistance of the photovoltaic modules is increased, which becomes the heat insulation layer on the photovoltaic modules and affects their heat dissipation.The current and voltage of some single cells in solar cell modules have changed.As a result, the product of local current and voltage of solar cell modules increases, resulting in local temperature rise on these modules.The defects of some single cells in solar cell modules may cause the components to heat up locally when working, which is called "hot spot effect".When the hot plate effect reaches a certain level, the solder joints on the module melt and destroy the grid line, resulting in the scrapping of the whole solar cell module.According to industry data, the hot spot effect reduces the actual life of solar cell modules by at least 10%.(2)occlusion effectDust is attached to the surface of the panel, which will block, absorb and reflect light.The most important one is the blocking effect on light, which affects the absorption of light by photovoltaic panels, thus affecting the efficiency of photovoltaic power generation.Dust deposition in the panel component by the smooth surface, the first will make the panel surface light transmittance decreased;Secondly, the incident Angle of some light will be changed, resulting in uneven propagation of light in the glass cover.Studies have shown that under the same conditions, the output power of clean panel components is at least 5% higher than that of grime components, and the higher the amount of grime, the greater the degradation of component output performance.(3)corrosion effectThe surface of photovoltaic panel is mostly made of glass. When wet acid or alkaline dust is attached to the surface of the glass cover, the glass surface will be slowly eroded, resulting in potholes on the surface, resulting in diffuse reflection of light on the surface of the cover, and the spread uniformity in the glass will be destroyed.The rougher the cover of the photovoltaic module is, the smaller the energy of refracting light is, and the energy actually reaching the surface of the photovoltaic cell decreases, resulting in the decrease of the generation of the photovoltaic cell.And rough, sticky surfaces with adhesive residues are more likely to accumulate dust than smoother surfaces.And the dust itself will absorb dust, once the initial dust exists, it will lead to more dust accumulation, accelerating the decline of photovoltaic cell power generation. 2.How to detect the components from the inverter end?Group is string of monitoring technology in inverter components input, current sensor and voltage detection device installation, detect each group of voltage and current value, through the analysis of the voltage and current of each group, so as to determine whether each string of operation of the apparently normal, if any abnormal timely according to the alarm code, and precise positioning abnormal group list.And can upload the fault record to the monitoring system, so that the operation and maintenance personnel can timely find the fault.Although the cluster monitoring technology increases the cost a little, it is still insignificant for the whole photovoltaic system, but it plays a big role:(1)early component problems, such as component dust, lobes, component scratches, hot spots and other problems, were found in a timely manner, which were not obvious at the early stage. However, by detecting the difference of current and voltage between adjacent groups, it was possible to analyze whether there were faults in the group strings.Timely handling to avoid greater losses.(2)when the system fails, no professional on-site detection is needed to quickly determine the fault type, accurately locate the group string, and timely solve the problem by operation and maintenance personnel to minimize the loss. 3.Component cleaning(1)manual cleaningManual dry cleaning component: manual dry cleaning is the use of long hair mop with special cleaning agent for cleaning, the use of oil electrostatic dust agent.Mainly USES the electrostatic adsorption principle, has the adsorption dust and the sand particle the function, can enhance the cleaning tool to absorb the dust decondulization ability, effectively avoids the dust sand particle flying in the cleaning.(2)automatic cleaningSemi-automatic cleaning. At present, this kind of equipment is mainly refit with engineering vehicle as the carrier, with large power and high efficiency. The cleaning work has a good consistency of pressure on the components, and will not produce unbalanced pressure on the components, resulting in hidden cracks of the components.The automatic cleaning method is to install the cleaning device on the photovoltaic module array and realize the automatic cleaning of the photovoltaic module by the program control of the motor rotation.This cleaning method is costly and complex in design.

Why should photovoltaic power stations be installed at the optimum Angle?

1.What is the best dip Angle?In a narrow sense said, if the fixed photovoltaic phalanx under the Angle of inclined plane receives the largest annual total radiation, says the Angle for optimum Angle, can also be in the best Angle corresponding obliquity, generating the highest yields the highest corresponding obliquity, a few months of the highest power Angle, and other various limited conditions to calculate the optimal dip Angle.2.Why do you need the best Angle?In order to receive more solar radiation, it is necessary to obtain an optimal dip Angle from the perspective of annual radiation reception through theoretical calculation, and this dip Angle is the optimal dip Angle.3.How to calculate the best inclination Angle?Based on the calculation and accumulation of radiation data and longitude and latitude, the annual total radiation received amount of photovoltaic square array with different inclinations is obtained, and the Angle with the largest annual total radiation amount is selected as the best Angle.4.What are the main factors affecting the optimal inclination Angle?The main influencing factors of the optimal dip Angle include: (1) latitude, the difference of latitude will affect the variation characteristics of the solar altitude Angle, thus affecting the optimal dip Angle;(2)The distribution of radiation amount in each month, if the radiation amount in a year is more concentrated in the month with high Angle of the sun, it will make the optimal inclination larger, otherwise it will become smaller;(3) direct scatter ratio, direct radiation has directivity, and scattered radiation is isotropic, so their respective proportion in the total radiation also has a certain impact on the optimal inclination.5.Does the power generation of photovoltaic power station have to be the highest under the optimal inclination Angle?Not for the best Angle of the narrow sense, in the order specification for design of photovoltaic power station, to determine the best Angle of interaction of (this time without considering the array block), according to Angle to determine photovoltaic phalanx north-south gap, and when the spacing is determined, between before and after the photovoltaic phalanx is shadows shade can be affected, the slope of radiation and the spacing and dip Angle on generating stations dynamically determine two factors, so the Angle and the best Angle of the largest electricity, there will be a gap between but unless there are other limit conditions, generally not too big gap between the two.6.Does the photovoltaic power station yield the highest under the optimal inclination Angle?For the narrow sense of the best Angle is not, sometimes less than the best Angle Angle has a higher return.Optimum inclination means high radiation reception, but it also means large footprint.For example, in a limited site area, the installed capacity will continue to increase as the optimal inclination decreases.The decrease of inclination Angle will reduce the power generation, while the increase of installed capacity will increase the power generation. Therefore, the final Angle with the highest profit still needs to be determined through further technical and economic comparison in combination with external conditions.7. Is the optimum Angle absolute?No, because of the climate uncertainty, the optimum inclination can actually only be called the relative optimum inclination based on historical data.First of all, the optimal inclination Angle will be different with different historical radiation data. There are some differences between the calculation of the optimal inclination Angle with 10 years of historical data and 20 years of historical data.Second, the historical average represents a high probability of local radiation characteristics, but is not necessarily the optimal choice for a given year.

What do you need to know about photovoltaic systems?

Solar photovoltaic power generation system has the following characteristics:- no rotating parts, no noise;- no air pollution, no waste water discharge;- no burning process, no fuel;- simple maintenance, low maintenance cost;- operational reliability and stability;- long life of solar cells is a key component of solar cells, and the life of crystalline silicon solar cells can reach more than 25 years;Scaling up as needed is easy.Photovoltaic system is widely used. The basic application forms of photovoltaic system can be divided into independent power generation system and grid-connected power generation system.The main application fields are space shuttle, communication system, microwave relay station, TV differential turntable, photovoltaic pump, no electricity area and home power supply.With the development of technology and the need of sustainable development of the world economy, developed countries have started to systematically promote urban grid-connected photovoltaic power generation, mainly building residential rooftop photovoltaic power generation system and mw centralized large-scale grid-connected power generation system.In terms of transportation and urban lighting, the use of solar photovoltaic system is vigorously promoted.The scale and application forms of photovoltaic systems vary, for example, the scale of the system is large, ranging from 0.3-2w solar courtyard lights, to mw solar photovoltaic power stations, such as 3.75kwp family rooftop power generation equipment, dunhuang 10MW project.Its application form is various, can be widely used in household, transportation, communication, aerospace and other fields.Although the size of photovoltaic system is different, its composition and working principle are basically the same.Photovoltaic module matrix: solar cell modules (also known as photovoltaic cell modules) are formed by means of series and parallel connection according to system requirements, and convert solar energy into electric energy output under sunlight irradiation.It is the core component of solar photovoltaic power generation systemBattery: stores the energy produced by solar cell modules.When light is low or at night, or when the load demand is greater than the power generated by the solar module, the stored energy is released to meet the load's energy demand.It is a storage solar photovoltaic system.Part ability.At present, solar photovoltaic system is widely used in lead-acid batteries.For demanding systems, a deep discharge valve is usually used to regulate sealed lead-acid batteries and deep discharge aspirated lead-acid batteries.Controller: adjust and control the charging and discharging state of the battery, and control the solar cell module and the power output of the battery to the load according to the power demand of the load, which is the core control part of the whole system.With the development of solar photovoltaic industry, the function of controller is becoming more and more powerful, and there is a trend to combine the traditional control part, inverter and monitoring system.For example, AES SPP and SMD series controllers integrate the three controllers.Inverter: in a solar photovoltaic power supply system, if an ac load is included, the inverter device converts the dc power generated by the solar cell module or the dc power released by the battery into the ac power required by the load.The basic working principle of solar photovoltaic power supply system is that the rechargeable battery can meet the load demand through the sunlight illumination under the control of the controller or under the condition of direct supply load, if the sunlight is insufficient or the battery is controlled by the controller at night.For photovoltaic systems with alternating current load, an inverter is also needed to convert dc to ac.There are many applications of photovoltaic systems, but the basic principles are similar.For other types of photovoltaic systems, only the control mechanisms and system components differ according to actual needs.

What are the classifications of photovoltaic systems?

1.independent photovoltaic power generation systemIndependent photovoltaic power generation is also called off-grid photovoltaic power generation.Is mainly composed of solar cell components, controller, battery, if the power supply for ac load, also need to configure the ac inverter, including villages in the remote area power supply system for stand-alone pv power stations, solar household power supply system, signal power, cathodic protection, solar street lamp, etc with a battery can be stand-alone photovoltaic power generation systems.2.Grid-connected photovoltaic power generation systemGrid-connected photovoltaic power generation is the direct current generated by solar modules is converted into ac power in line with the requirements of the grid by grid-connected inverter and then directly connected to the public grid.It can be divided into grid-connected photovoltaic power generation system with storage battery and grid-connected photovoltaic power generation system without storage battery. Grid-connected photovoltaic power generation system with storage battery has schedulability, which can be incorporated or withdrawn from the power grid according to the needs. It also has the function of backup power supply, which can provide emergency power when the power grid is cut off for some reason.Grid-connected photovoltaic systems with batteries are often installed in residential buildings;Grid-connected photovoltaic power generation systems without batteries do not have the functions of schedulability and backup power, and are generally installed on larger systems.3.Distributed photovoltaic power generation systemDistributed photovoltaic power generation system can be divided into centralized large-scale grid-connected photovoltaic power station and distributed photovoltaic system.The main feature of the centralized large-scale grid-connected photovoltaic power station is that it can directly transmit the power generation to the power grid, and then uniformly allocate the power to the users.This kind of power station has large investment, long construction period and large occupation area.However, the distributed photovoltaic system has the advantages of small investment, fast construction, small occupation area and large policy support.

What are the advantages of solar systems?

1. The solar energy is inexhaustible, the earth's surface to withstand the solar radiation energy, can satisfy the global energy demand of 10,000 times.Just installing solar photovoltaic systems in four percent of the world's deserts would satisfy global demand.Solar power generation is reliable and will not be affected by energy crisis or unstable fuel site;2.The solar energy can be used everywhere and can be supplied to nearby places without long-distance transportation, thus avoiding the loss of long-distance transmission lines;3.solar energy does not need fuel, the operation cost is very low;4.solar power generation without moving parts, not easy to use damage, protection brief, especially suitable for unattended use;5.solar power generation will not produce any waste, no pollution, noise and other public hazards, no adverse impact on the environment, is an ambitious clean energy;6.The construction cycle of solar power generation system is short, convenient and flexible, and the solar energy array capacity can be added or reduced arbitrarily according to the increase or decrease of load to avoid waste.It is necessary to choose the right system according to the situation, and cherish it in the process of use.