A photovoltaic inverter like 2000w pure sine wave inverter or 3000w inverter, is an important component of any home solar power system, used to convert direct current (DC) power from photovoltaic panels into alternating current (AC) power, similar to standard grid power. So as one of the core components of the photovoltaic system, how often does the inverter need to be replaced?
It is generally believed that inverter lifespan is limited by internal electronic components (IGBTs, capacitors, inductors, etc.), and their service life generally does not exceed 10 years. During the entire life cycle of a photovoltaic power station, the inverter must be replaced at least once. This article will give you a detailed introduction to inverter lifespan.
Main content:
1. How long is the life of a solar inverter?
In addition to the outer shell, the interior of the inverter can basically be regarded as a synthesis of electronic components, so the inverter lifespan is greatly affected by the electronic components.
Generally speaking, residential photovoltaic systems are considered to last more than 25 years, and some photovoltaic module manufacturers even promise a 30 or 40-year power generation life cycle. But the PV inverter lifespan ranges from 10 to 25 years, depending on the type. Most average inverter lifespan, and the lifespan of energy storage inverters and hybrid inverters is 10 years. However, microinverters, such as 500w inverter, last even longer.
Even within one type of PV inverter, the lifespan of individual models may vary. Additionally, other factors determine the lifespan of each model, including the brand you purchase, quality, warranty, operating temperature, and ventilation, which all play a vital role in the inverter lifespan.
Therefore, you are likely to encounter a worn out inverter in your operation at least once and have to replace it with a new one. Because as the internal parts of the inverter wear out from long-term use, the inverter will continue to be less efficient and more likely to fail when it reaches the end of its inverter lifespan.
2. Factors affecting inverter lifespan
The inverter lifespan has a lot to do with the usage environment and the quality of the components.
① Inverter components
Components include structural parts, circuit boards, power switching tubes, capacitors, LCDs and fans, and other parts. The inverter lifespan is determined by the components with the shortest lifespan, usually IGBTs, capacitors, inductors, etc., which generally have a lifespan of no more than 10 years.
For example, electrolytic capacitors, which are one of the most failure-prone devices of the inverter. The electrolyte in the electrolytic capacitor will gradually evaporate and dry out, resulting in an increase in the equivalent series resistance of the electrolytic capacitor, and at the same current, the higher resistance will cause the capacitor to heat up, exacerbating the evaporation of the electrolyte, and ultimately leading to device failure.
Another component is thermal conductive silicone grease, whose lifespan is about 10 years. If the thermal grease fails, the heat generated by electronic components cannot be conducted away in time, and the components will quickly age and be damaged. Other components that with a lifespan of less than 25 years include LCD screens, plastic connectors, cables, terminal blocks, etc.
② Inverter usage environment
If components are internal factors, then the use environment is the external factor that affects the inverter lifespan. Usually, inverters must undergo outdoor empirical testing, including various performance tests such as weather resistance, acid and alkali resistance, salt spray, waterproofing, and high and low temperature cycles.
Research shows that the inverter lifespan is greatly affected by the installation location of the equipment, and the TTF (time to failure) of outdoor installation is shorter. Because the temperature inside the inverter is the most important factor affecting the inverter lifespan (especially for components).
Direct exposure to sunlight will increase the operating temperature; installation in a confined space will affect heat dissipation; accumulation of dust on the surface will also affect heat dissipation; exposure to the sun and wind blowing or rain will affect the life of the casing, connectors, etc. In these case, even the best solar inverter won't last as long as you might expect.
Therefore, when installing the inverter, you need to consider providing a suitable working environment for it. Do not think that just because the inverter is designed for outdoor applications, the casing of the inverter is made of metal, so its environmental tolerance is also that strong.
If it is installed outdoors, it is best to install it under the eaves of the backside of the sun or under the photovoltaic modules, or install a sunshade and rainproof shed to provide sunshade, rainproof and cooling for the inverter; try to keep it stay away from high-temperature areas such as boilers, fuel-fired hot air fans, and heating pipes, and try to improve the measures such as sand prevention, dust prevention, and leaf fall prevention.
3. How to extend inverter lifespan
It is generally believed that the main culprits that affect electronic components are high temperature, dust, oxidation, moisture, etc. Therefore, the inverter lifespan is also affected by these factors, which requires operators to perform necessary maintenance to extend their inverter lifespan.
① When designing the photovoltaic system, it is necessary to consider the matching of the capacity of the inverter and the photovoltaic system.
The power generation capacity of the photovoltaic system changes with the light intensity, so there is a power generation curve every day, and in most cases the power generation capacity of the photovoltaic system is lower than the inverter capacity. Therefore, many designers will choose a capacity overprovisioning of 10-30% to reduce the investment cost of the inverter.
② Like all other components in a photovoltaic installation, the inverter requires regular maintenance and upkeep.
The most important goal is to prevent dust and excessive humidity from affecting inverter lifespan. Dust can enter the equipment and reach the circuit board, possibly causing a short circuit; excessive humidity can accelerate corrosion, causing the inverter's electrical terminals and connections to rust faster.
③ Avoid overheating.
Inverters generate heat when operating, and photovoltaic inverters rely on several electrical components inside that are sensitive to extreme temperatures. In addition to the heat dissipation design of the inverter itself, the installation and placement of the photovoltaic inverter is also critical to prevent overheating.
If it is under direct sunlight, the temperature inside the inverter will easily rise; it is also not conducive to dissipate heat when being in an unventilated environment. When these conditions persist for an extended period of time, they can damage the components of the PV inverter and shorten inverter lifespan.
④ When the system is connected to the grid, the inverter faces the risk of overvoltage and undervoltage.
Too high or too low grid voltage may cause problems to the inverter and prevent it from operating normally.
⑤ Unresolved fault codes.
When the PV inverter occasionally encounters a problem, it will tell you what the problem is by displaying a fault code. You must fix the problem and clear the code as quickly as possible rather than leaving the inverter working sick.
In summary, You can maximize the your inverter lifespan by placing it in a cool, well-ventilated area and maintaining it regularly.
4. Repair it or replace it?
As mentioned earlier, the quality of the inverter components will affect the inverter lifespan. Failure of the inverter components may affect the power generation and stop working, or it may not affect the power generation. The failure of capacitors, silicone grease, etc. is also a gradual process, which will gradually reduce the efficiency of the inverter. Therefore, it is recommended to perform maintenance on the inverter to delay the aging of the inverter components.
When the inverter fails or the efficiency drops to a certain degree, should you repair it or replace it?
As a power electronic device, repair is possible at any time, but you need to consider whether to repair or replace it economically. Some may be simple faults, such as display failure and shell corrosion, which do not affect the power generation.
And some may affect the power generation, such as opening the inverter case and finding that the wiring is loose and the silicone grease is gone (just like the thermal conductive silicone grease of computer), these may be things that you can do yourself or ordinary electrical repairmen, so you might give them a try first.
For some complex faults, professional maintenance personnel may be required to carry out maintenance, which may be parts replacement or may involve the whole machine replacement.
At present, string inverters are generally repaired by whole machine replacement, especially some imported brand inverters in the early days, which may no longer provide repair services; even for domestic inverters, it is not easy to find suitable components due to the fast iteration of inverter technology.
The price of a 5kW string inverter 10 years ago was about RMB 15,000, with an efficiency of about 95%, and the price in 2018 was about RMB 3,000, which is only 20% of what it was 10 years ago, with an efficiency of about 98%; and now, by 2023, the price of a 5KW inverter is about RMB 1,000, which is more advanced in technology, with a higher efficiency, and a fuller range of functions, at a lower price. Similar to household appliances, it is better to replace them rather than repair them.
For centralized inverter failures, modular repair is generally used. The overall value of centralized inverter is, so as the replacement cost. Usually the whole machine is divided into a number of modules, so you should first detect which module is faulty, and then replace the faulty module for longer inverter lifespan.
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