Solar inverters play a crucial role in solar power systems to convert the direct current (DC) produced by the solar panels into Alternating Current (AC) to power household appliances and several other electrical equipment.
Since inverters are the core component of solar power systems. A failure can lead to numerous problems such as the complete shutdown of the solar system which can lower the system’s efficiency and profitability.
The common causes for solar inverter failure include grid and isolation faults, overheating, ultrasonic vibrations, over and under voltage, capacitor failure, faulty Maximum PowerPoint Trackers (MPPTs), and short circuits. In this article, you can find the solutions to these problems in detail.
Common Solar Inverter Failure and Solutions
Overheating
Solar inverters can be prone to overheating due to several reasons such as environmental factors, system issues, design, and manufacturing issues as explained below in detail:
1. Environmental Factors: In desert regions, higher ambient temperatures can reach up to 120 °F (49 °C), increasing the chance of overheating. Moreover, if the inverters are installed in sunny locations without proper shading, the internal temperatures become high due to solar radiation. In agricultural areas, the accumulation of dirt and debris reduces airflow and heat losses.
2. System Issues: Connecting multiple panels to an inverter with insufficient capacity can cause overheating. A limited installation space with a shortage of air flow can increase the temperatures. At times, improper grounding or wiring can cause system failure and overheating.
3. Design and Manufacturing Issues: The low-cost inverter models have inadequate heat dissipation capabilities and a poorly designed cooling system such as the undersized fan can cause overheating. For instance, the failure of a temperature sensor or using substandard capacitors can also cause overheating.
The location and installation of solar inverters significantly affect their risk of overheating in the following ways:
- Regions with extreme climates can contribute to the heating issues in microinverters due to higher ambient temperatures.
- Inverters installed in areas with inadequate air flow or direct sunlight can cause overheating.
- There are chances for solar inverters to get damaged if they are installed in smaller areas and to ensure optimal space, there should be an open space of at least 30 cm on all sides of an inverter for proper ventilation.
These are the effective solutions to prevent overheating:
- Regular maintenance and cleaning
- Find the ideal placement for installation.
- Ensure the system setup is perfectly configured.
- Increased ventilation allows heat to escape.
- Turn off the inverter if you find the device becoming overheated.
Capacitor Wear
Capacitor fails due to several reasons:
- The dielectric material in the capacitor is loaded to the complete potential when a device is charged due to smaller capacitor sizes. After a certain time, the material deteriorates and eventually fails due to high electrical stresses.
- Failure of electrical, mechanical, or environmental overstress due to dielectric failure during functioning, or manufacturing defects.
- Low-quality capacitors with manufacturing defects might fail at an early stage under standard operating conditions.
The temperature affects the capacitors’ lifespan in the following ways:
- Dielectric Properties: The temperature changes due to permittivity and dielectric strength.
- Conductor’s resistance: The resistance of the capacitor’s conductive plates increases with the increase in temperature.
- Physical Dimensions: The temperature variations affect the physical dimensions as the capacitor expands or contracts, which can affect the distance between the conductive plates.
You need to follow these steps to ensure capacitors operate effectively for longer periods:
- Handle with care to avoid physical damage.
- Proper installation should be done following the manufacturer’s guidance.
- Operate within the specified voltage and temperature to prevent damage and increase lifespan.
- Perform regular inspections and maintenance to check for any physical damages.
- Carefully discharge the capacitors to avoid electrical shocks.
- Avoid overcharging such that the charging voltage does not exceed the capacitor’s rated voltage.
- Using higher-quality capacitors can result in a longer lifespan. For instance, ceramic capacitors can retain charge for a few days to wells, whereas electrolytic capacitors might hold charge for a few weeks to months, but the leakage rates are higher due to the presence of electrolytes.
Ultrasonic Vibrations
Typically, the ultrasonic vibrations that originate in the cores of inductive components can cause friction which can generate unwanted heat by the device and damage components in the inverter. At times, the parts are dislocated or damaged which can result in component failure or malfunctioning.
You need to follow these maintenance practices to prevent damage caused by vibrations and deterioration of electrical connections:
- Perform regular inspections and provide additional attention in case of breakdown, energy production loss, damages to expensive equipment, and other serious losses.
- Dirty inverters become extremely hot when thick dirt accumulates in the frame and blocked spaces minimize the flow of cool air. The insulation life is reduced due to excess heat, which eventually causes motor failure.
- Check for corrosion and winding failures that may indicate internal deterioration or external modifications.
Over and Under Voltage
Overvoltage occurs when the voltage exceeds the rated value which can cause insulation damage to electrical appliances, leading to short circuits. When the high inertial loads decelerate too quickly, the motor turns into a generator and increases the DC voltage. This results in damaging the electrical components due to the excess heat generated by the sudden increase in voltage.
You can fix the over-voltage issues in the following ways:
- Switch on the overvoltage controller and check if the voltage supply is constant or high.
- Verify the operation of the brake chopper and resistor.
- Enhance the deceleration time and use the stop function whenever possible.
- Attach a frequency converter with a brake chopper and brake resistor.
- Substitute with a regenerative drive.
Undervoltage happens when the average voltage of any electrical equipment is below the rated voltage, which leads to a decrease in the equipment’s performance and durability. A missing voltage supply from a blown fuse or faulty isolator results in under voltage which can be fixed by checking these errors:
- Main supply and fuses.
- Operation of isolator and contactor.
- If the incoming voltage is low.
Grid Faults
Grid voltage fault occurs in the inverter when the AC voltage is out of range. In other words, when the solar inverter loses its connection with the grid, the voltage levels might be too high or low, or when the frequency deviates from the standard values of 50 or 60 Hz. A grid fault can halt energy generation, which can lead to zero output until the issue gets resolved and reconfiguration occurs.
These are the main technologies that can protect inverters from electrical breakdowns:
1. Surge Protectors or Voltage Regulators used on the input side of the inverter help to safeguard against voltage spikes or surges to ensure that the inverter operates smoothly and efficiently.
2. Smart Gate Drivers such as Toshiba’s TLP5214 smart gate-driver1 provide thermal isolation to ensure the user’s safety and protect the low-voltage control circuit from harmful electrical situations that occur on the high-power side of the circuit’s control.
You need to choose the high-quality grid-tie inverter to ensure higher efficiency, long-term savings on your electricity bills, simplicity, effective utilization of renewable energy, improved performance, and enhanced durability.
Isolation Faults
Isolation faults occur due to the damage to the protective layer of the wiring during fitting leading to a short circuit between the DC and AC connection. Additionally, these issues are caused because of excess moisture or poor connection in the junction box of the solar panel. The error that appears on the screen is called an “isolation error” or “isolation fault”.
By placing the inverter in a cool, dry environment and avoiding places like a pool or fountain, moisture can be prevented from causing any damage to your system.
Regular maintenance plays a crucial role in preventing isolation faults by providing the following benefits:
- Increased efficiency: Avoid accumulation of dust, bird droppings, and other environmental factors to increase sunlight absorption.
- Longer Lifespan: Proper maintenance slows down degradation and extends the lifespan of solar panels.
- Enhanced Energy Production: Well-maintained solar panels help to generate the maximum amount of electricity, which helps to optimize your return on investment and contribute to more sustainable energy in the future.
- Identify damages or faulty components: Regular inspection helps to detect damages or faulty parts, minimizes system failure, and reduces downtime.
- Safety Ensured: Any wiring issues or safety hazards can be identified by performing regular maintenance that helps to prevent accidents and safeguards your property and residents.
Faulty MPPT
Maximum Power Point Tracking (MPPT) is a crucial technology to improve the efficiency and output of solar panel systems. The main purpose is to constantly maintain the maximum power point of solar panels, thereby activating the production of the highest amount of power from sunlight.
The main challenge faced by the MPPT is the power transfer from the PV system, which depends upon factors such as the availability of sunlight, shading, temperature of the solar panel, and electrical load configuration. If these conditions fluctuate, the load characteristic activates the effective power transfer changes.
These are the maintenance practices that ensure MPPT modules perform optimally:
1. Frequent Cleaning: The accumulation of dirt, dust, and debris can block the airflow and affect the performance, and using a soft cloth or brush you can wipe the exterior surface.
2. Connection Review: Ensure that the connections aren’t loose or damaged to avoid electrical problems and increase the performance of the MPPT hybrid controller by inspecting the connections which include the solar panel, battery, and load.
3. Heat Control: If the MPPT controller is installed in a well-ventilated area with proper airflow, the excess heat can be minimized to increase the lifespan. This is only possible if the modules aren’t exposed to direct sunlight or other heat sources. If the controller is mounted in a limited space, you should opt for installing a cooling fan to maintain the lowest operating temperatures possible.
4. Software Update: It’s important to check software updates from the manufacturer’s official website that include bug fixes, performance enhancements, and new features.
5. Battery Maintenance: Proper maintenance of the battery is essential to ensure overall performance and increase the lifespan of the system. You need to check the battery terminals are clean and free from corrosion.
Solar Inverter Short Circuits Reasons
Commonly, short circuits occur in solar inverters due to the combination of various factors such as:
1. Uncharged batteries: A loose connection between batteries and inverter doesn’t ensure proper charging and leads to a short circuit. This occurs due to faulty or inadequately sized battery banks for inverter specifications, and a failed battery charge controller inside the inverter that might exceed the recommended lifespans.
2. Lack of Sunlight: Inverters can malfunction if the solar panel doesn’t receive sufficient sunlight to generate electricity, thereby leading to short circuits.
3. Moisture and improper installation: The excess level of moisture content and improper solar panel installation can lead to short circuits.
These are the possible solutions to address the short circuit issues in inverter:
- Ensure proper installation of solar panels and check for any damaged or loose connections.
- Check for any damages or loose connections.
- Perform regular inspections to avoid any malfunctioning.
- Try to reset the inverter by turning it on and off if you observe any signal error codes.
- Avoid placing inverters near radiators or other sources of heating.
You should check for professional help when there are complex electrical issues, lack of knowledge about specialized tools, warranty, and safety concerns.
Conclusion
Solar inverters have an important role in converting DC power into usable AC power. Also, it addresses many frequently occurring solar inverter failure issues and implements safety measures that are essential for protecting your solar system and its investment for many years.
Most importantly you need to consider environmental factors, inverter quality, maintenance practices, monitoring, and warranty because these factors play a significant role in the long-lasting strength of your solar power inverter.
By understanding these factors that affect the lifespan, you can ensure constant performance and long-lasting periods of your solar inverters.
Regular maintenance is compulsory for the long-term performance and better efficiency of solar inverters. Most importantly panels, inverters, cabling, and other components used in solar power plants have to be replaced over time as they become non-usable. Therefore, regular maintenance and repairs will extend the system’s life and ensure that it functions properly without any failures.
Moreover, you need to take additional care by preventing the accumulation of dust on the inverter’s surface. This approach helps to maintain proper airflow and avoids overheating to increase the unit’s lifespan. Furthermore, you should check if there are any loose connections and other signs of malfunction. Overall, these observations and maintenance strategies are essential for the optimum efficiency of solar inverters.
Ray is an avid reader and writer with over 25 years of experience serving various domestic and multinational private and public energy companies in the USA.