What is a Micro Inverter?
A micro inverter is a small, compact inverter designed to convert direct current (DC) electricity generated by a single solar panel into alternating current (AC). Each solar panel in a photovoltaic (PV) system is paired with its own micro inverter, ensuring that the output of each panel is converted and optimized individually. This approach provides panel-level power management and monitoring, making micro inverters a popular choice for residential and small-scale commercial solar installations.
What is a String Inverter?
A string inverter is a centralized inverter that converts DC electricity generated by a series (or string) of solar panels into AC. Panels are connected in series to form a string, and the combined DC power from the string is sent to the string inverter for conversion. This centralized approach simplifies system design and is commonly used in larger-scale installations such as commercial and utility-scale solar projects.
What is the difference between a string inverter and a micro inverter
Reliability
Micro Inverters: High reliability due to distributed architecture; Failure of one micro inverter affects only its associated panel, minimizing system-wide impact; Typically have a longer warranty, ranging from 10 to 25 years.
String Inverters: Reliability depends on the single centralized unit; A failure in the string inverter can disrupt the entire system until the issue is resolved; Warranty periods are usually shorter, around 5 to 15 years.
Working Principle
Micro Inverters: Operate at the panel level, individually optimizing and converting the output of each panel; Provide Maximum Power Point Tracking (MPPT) for each panel, ensuring optimal performance; Performance is unaffected by shading or malfunction of other panels.
String Inverters: Operate at the system level, converting the combined output of an entire string of panels; MPPT is performed for the entire string, so shading or underperformance of one panel can impact the entire string.
Pros and Cons
Micro Inverters:
Pros: Independent panel optimization ensures maximum efficiency; Better performance in shaded or complex installations; Enhanced monitoring with panel-level data.
Cons: Higher upfront costs; More components to install and maintain.
String Inverters:
Pros: Lower initial cost; Simpler installation process; Well-suited for uniform and unshaded installations.
Cons: Susceptible to shading and panel mismatches; Limited flexibility for system expansion.
Cost
Micro Inverters: Typically more expensive due to the need for one inverter per panel. Installation costs can also be higher due to increased complexity.
String Inverters: Lower overall cost, as one inverter can handle multiple panels.
Efficiency
Micro Inverters: Higher efficiency in non-ideal conditions, as each panel operates independently.
String Inverters: Can achieve high efficiency in ideal conditions but are affected by shading and panel mismatches.
Size
Micro Inverters: Compact and installed behind each panel, requiring no additional wall space.
String Inverters: Larger units typically installed near the main service panel or utility meter.
Lifespan
Micro Inverters: Generally have a longer lifespan, with warranties often extending up to 25 years.
String Inverters: Shorter lifespan, with warranties typically ranging from 5 to 15 years.
Conclusion
Micro inverters and string inverters each have their unique advantages and limitations. The choice between them depends on the specific requirements of the solar installation, including budget, site conditions, and system complexity.
