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Aluminum electrolytic energy storage capacitors are widely used in photovoltaic inverters. The current generated by photovoltaic power generation systems is direct current, but household electricity is primarily supplied as alternating current, and solar power generation will ultimately move towards grid operation. This means that solar power generation must convert direct current into alternating current through an inverter to drive household appliances and other loads. Therefore, inverters play a crucial role in solar power generation systems.
High voltage energy storage capacitors
Generally, high-power photovoltaic inverters directly merge the converted alternating current into the high-voltage power grid. However, from the perspective of safety regulations, the output voltage of the photovoltaic cell group is generally no higher than 900V. Two 450V electrolytic energy storage capacitors can be selected in series, but to improve safety, two 500V electrolytic capacitors can be selected in series. Therefore, capacitors with a high voltage level are required to reduce the number of capacitors in series and improve reliability.
High tolerance to ripple current of energy storage capacitors
The current flowing through the capacitor in the photovoltaic inverter is 0.44 times the effective value of the inverter's output current. If the output voltage of the photovoltaic inverter is line voltage 250V, the output current corresponding to 1kW power output is approximately 2.54A. The current flowing through the bus dc link capacitor is 1.12A. The DC bus capacitor of a 100kW photovoltaic inverter needs to flow an effective value current of 112A. The rated current of the selected capacitor should not be lower than this value. If the rated current of a single electrolytic capacitor cannot meet the requirements, multiple electrolytic capacitors should be selected in parallel to obtain the required current value. Therefore, a single high-tolerance-to-ripple-current electrolytic capacitor is required to reduce the number of electrolytic capacitors in parallel and improve overall reliability.
Long life of energy storage capacitors
The service life of photovoltaic panel in a solar power generation system is up to 25 years, while inverters in photovoltaic systems can only be used for 5 to 10 years. Therefore, the service life of the inverter in a solar power generation system is required to meet the level of 25 years. For passive components, such as electrolytic capacitors, the negative electrode is electrolyte, which will slowly dry up and fail with the increase of usage time. This undoubtedly requires the electrolytic capacitor industry to manufacture longer-life electrolytic capacitors to meet the requirements of photovoltaic inverters.
Electrolytic energy storage capacitors are the most widely used in the photovoltaic inverter industry. After reliability testing, they fully meet the requirements of long life, high ripple, and high voltage in the new energy field. If you are looking to purchase capacitors for photovoltaic inverters, please feel free to contact us at Safe Electronics. We will provide you with stocks and technical support promptly.
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