Solar power is the use of semiconductor interface photovoltaic effect and the direct conversion of light energy into electrical energy technology. The key component of this technology is solar cells. Solar cells are connected in series after encapsulation protection can form a large area of the solar cell module, together with the inverter, power controller and other components to form a solar power generation device. The advantages of solar power is less subject to geographical restrictions, because the sun shines on the earth; solar energy system also has the advantages of safety and reliability, no noise, low pollution, no need to consume fuel and set up transmission lines can be in situ to generate electricity and power supply and construction of the same period of time is short.
Solar inverter as an electronic product, composed of numerous components. Inverter, also known as power regulator, according to the use of inverter in solar power generation system can be divided into independent power supply and grid-connected use of two kinds. According to the waveform modulation method can be divided into square wave inverter, step wave inverter, sine wave inverter and combined three-phase inverter. For inverters used in grid-connected systems, they can be divided into transformer-type inverters and transformerless inverters according to the presence or absence of transformers.
Solar inverter as the testing center of the whole power station, up to the DC components, down to the grid-connected equipment, basically all the power station parameters can be detected through the inverter. General inverter as long as the grid-connected state, monitoring the display of the power curve for the normal fluctuation shape, proving that the power plant is running stable, if there is anomaly, you can check the health of the power plant supporting equipment through the feedback information from the inverter. The following is a compilation of some of the common causes of solar inverter failure analysis and treatment methods:
1、Solar inverter screen does not show
Failure analysis: there is no DC input, the inverter LCD is powered by DC.
Possible causes:
(1) Component voltage is not enough. Inverter working voltage is 100V to 500V, below 100V, the inverter does not work. The module voltage is related to the solar irradiance.
(2) The PV input terminal is reversed. The PV terminal has positive and negative poles, which should correspond to each other and not be reversed with other group strings.
(3) DC switch is not closed.
(4) When the components are connected in series, one of the connectors is not connected properly.
(5) One component is short-circuited, resulting in other strings can not work.
Solution: Measure the DC input voltage of the inverter with a finish meter. When the voltage is normal, the total voltage is the sum of each component voltage. If there is no voltage, test whether DC switch, terminal, cable connector, component, etc. are normal in turn. If there are multiple components, separate separate access test. If the inverter is used for a period of time, no reason is found, then the inverter hardware circuit failure, you can contact the manufacturer after-sales.
2、Solar inverter is not grid-connected, the screen shows that the grid is not connected.
Failure phenomenon: the inverter is not connected to the grid, the screen shows that the grid is not connected.
Failure analysis: the inverter and the grid is not connected
Possible reasons:
(1) AC switch is not closed.
(2) The AC output terminal of the inverter is not connected.
(3) When wiring, the inverter output terminals on the row is loose.
Solution: Measure the AC output voltage of the inverter with a multimeter voltage gear, under normal circumstances, the output terminals should have 220V or 380V voltage, if not, in turn, detect whether the terminals are loose, whether the AC switch is closed, and whether the leakage protection switch is disconnected.
3、Screen display PV voltage is high
Failure analysis: DC voltage is too high alarm
Possible reasons: too many components are connected in series, causing the voltage to exceed the voltage of the inverter.
Solution: Because of the temperature characteristics of the components, the lower the temperature, the higher the voltage. The input voltage range of single-phase string inverter is 100-500V, and it is recommended that the voltage after stringing is between 350-400V. The input voltage range of three-phase string inverter is 250-800V, and it is recommended that the voltage after stringing is between 600-650V. In this voltage range, the inverter efficiency is higher, and power can be generated in the morning and evening when the irradiance is low, but not so much that the voltage exceeds the upper limit of the inverter voltage, causing alarm and shutdown.
4、Screen display PV insulation impedance is too low
Failure analysis: solar system grounding insulation resistance is less than 2 megohms
Possible causes: solar modules, junction boxes, DC cables, inverters, AC cables, terminals and other places there are wires to ground short-circuit or insulation damage, PV terminals and AC wiring shells loose, resulting in water.
Solution: Disconnect the power grid, inverter, in turn, check the resistance of each component wire to ground, find out the problem point, and replace it.
5、Screen display output leakage current is too high
Failure analysis: leakage current is too high
Solution: Remove the PV array input, and then check the peripheral AC power grid. Disconnect all DC and AC terminals, let the inverter power outage for more than 30 minutes, if you can recover on your own, continue to use, if you can not recover, contact the after-sales technical engineer.
6、Screen display grid voltage over range
Failure analysis: Grid voltage is too high. Grid impedance increases, the user side of solar power generation can not be digested, and transmission out of the impedance is too large, resulting in too high a voltage on the output side of the inverter, causing the inverter to protect the shutdown, or derating operation.
Solution:
(1) Increase the output cable, because the thicker the cable, the lower the impedance.
(2) Inverter close to the grid, the shorter the cable, the lower the impedance.
