The various components of solar system are as follows:
- Solar panels
- Mounting systems
- Balance-of systems (Inverters, Trackers, Junction boxes, combiners, transformers)
- Batteries (if required)
Now, while some of these components like solar panels may last for the system’s usable life, many of these are prone to faults and failures.
Why is this important?
There is focus on reducing the lifecycle costs of PV over its lifetime. The lifetime costs of a solar system include cost of capital, cost of system operations and maintenance and repair costs. The costs of maintenance and repair represents the major variable cost over the lifetime of a solar system.
In fact, although balance-of-system components comprise around 10% of total system costs, they represent about 70% of system failures. This means there is a need for special focus on maintenance.
In such a scenario, improving the system reliability has become an important issue.
What are the causes and likelihood of failure?
| Sources of failure | Causes of failure | Likelihood of failure |
| Solar panel | Environmental effects like wind loading and cyclic stresses, corrosion | Highly unlikely |
| Inverters | Insulation problems, overheating, cracks, wear and tear, improper installation | Likely (most unreliable component of a solar system) |
| Mounting systems | Corrosion, missing bolts | Unlikely |
| Batteries | Electrolyte leak, cracks in batteries, corrosion | Unlikely if maintained properly |
| Wiring and connections | Cracks, breaks, overloading, rodents | Unlikely |
Why do inverters fail so much and what is the current status?
The inverter failure rate is high due to the following reasons:
- Harsh environments they are placed in
- High operating temperatures
- Self-heating occurring inside the inverter
- The electrolytic capacitors and various switching devices such as fans, switches and relays that are not compatible with the 25 year lifetime of a solar system
Despite many of the unavoidable failure modes of inverters, the next-generation of micro-inverters are helping mitigate many of the design flaws associated with current inverters in the market, especially replacing electrolytic capacitors with thin film capacitors. This can go a long way in increasing inverter life.
Conclusion
It should be noted that of all the solar system components, inverters have a higher frequency of failure. Although PV modules offer warranties of up to 25 years, most inverters still offer only 10-15 years of warranty. They remain the weakest link in the PV value chain and have to be replaced long before any other components of a PV system.
It is worthwhile to note that the lesser the system components, the lower the system failure. So, it is suggested to keep your system as simple as possible to ensure longer and failure-free functioning.
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