The main difference between a string inverter and a micro inverter lies in their design, functionality, and how they manage solar panel output in a photovoltaic (solar power) system.
1. String Inverter:
- Overview: A string inverter is a central inverter that is connected to multiple solar panels in series (forming a “string”). It converts the direct current (DC) electricity produced by the panels into alternating current (AC) electricity that can be used by the home or fed into the grid.
- Functionality: All solar panels in the string operate at the same voltage and current, and their combined output is fed into the inverter.
- Efficiency: The performance of a string inverter is affected by the weakest or lowest-performing panel in the string (called the “weakest link” effect). If one panel in the string is shaded, dirty, or malfunctioning, it can reduce the overall output of the entire string.
- Cost: Typically less expensive than micro inverters because fewer inverters are needed (Inverter mounted on the wall rather than behind each panel).
- Best for: Larger systems with unshaded areas and uniform panel conditions, where the effects of shading or panel mismatch are minimal.
2. Micro Inverter:
- Overview: A micro inverter is a small inverter installed on each individual solar panel. It converts the DC electricity generated by each panel into AC electricity at the panel level, rather than centrally.
- Functionality: Each micro inverter works independently to optimize the performance of each solar panel. If one panel is shaded or underperforming, it does not affect the performance of other panels in the system.
- Efficiency: Micro inverters can improve the overall efficiency of a system, especially in situations where shading or panel mismatch occurs. They also allow for greater system monitoring at the panel level.
- Cost: Micro inverters tend to be more expensive than string inverters, as each panel requires its own inverter.
- Best for: Smaller systems or situations where shading, roof obstructions, or panel mismatch are concerns, and for installations where individual monitoring is important.
Key Differences at a Glance:
| Feature | String Inverter | Micro Inverter |
| System Design | One central inverter for all panels | One inverter per panel |
| Efficiency | Dependent on the weakest panel in the string | Each panel is optimized independently |
| Shading Sensitivity | Shading or dirt affects entire string | Shading affects only the shaded panel |
| Cost | Generally lower cost | Higher cost per panel (due to multiple inverters) |
| Installation | Simpler, fewer components | More complex (more inverters to install) |
| Monitoring | Typically no panel-level monitoring | Allows for individual panel monitoring |
| Best For | Large systems with minimal shading or uniform conditions | Systems with shading, roof obstructions, or need for granular monitoring |
Conclusion:
If you have a large, open roof with minimal shading, a string inverter is often the more cost-effective choice.
If you have shading issues, complex roof geometry, or want the flexibility of monitoring each panel’s performance, micro inverters might be a better fit, despite the higher initial cost.
