Solar inverters: string inverters VS miroinverters

Solar inverters serve one core function: to convert the direct current (DC) generated by solar panels into alternating current (AC), which is the type of electricity used in your home. There are two main types of home solar inverters, each with its own set of advantages and applications.

Microinverters are attached to the back of each individual solar panel. They are particularly well-suited for complex solar installations where panels may be installed on multiple roof planes facing different directions, or where there are areas of shading. Microinverters optimize the performance of each panel independently, ensuring that even if one panel is underperforming due to shading or orientation, the others can still operate at their maximum efficiency. This modular approach enhances the overall system performance and reliability.

String inverters, on the other hand, connect strings of solar panels in one central location. They are best for simple installations where all panels are installed on a single, unshaded roof plane, typically facing south. String inverters are generally more cost-effective and have been the traditional choice for many years. However, they operate at the level of the lowest-performing panel in the string, meaning that if one panel is shaded or underperforming, it can affect the entire string’s output.

Microinverters have gained significant popularity and are now the most widely chosen inverter option for several reasons. One key factor is their compliance with the National Electrical Code (NEC) and safety standards. Microinverters inherently meet the rapid shutdown requirements, which mandate that solar systems can quickly shut down in the event of an emergency to protect first responders and prevent electrical hazards. This built-in safety feature makes them a preferred choice for many homeowners and installers.

In contrast, string inverters need to be paired with additional components, such as DC optimizers or rapid shutdown devices, to comply with the NEC and safety standards. These additional components can add to the overall cost and complexity of the installation. However, for simple installations with a straightforward roof layout and minimal shading, string inverters can still be a cost-effective and efficient solution.

Each type of solar inverter has its own set of pros and cons, and the right one for you ultimately depends on your specific system design. If you have a complex roof with multiple orientations or areas of shading, microinverters are likely the best choice due to their ability to optimize individual panel performance. For a simple, unshaded roof with a uniform orientation, a string inverter paired with the necessary safety devices can be a more economical option.

String inverters

A string inverter is installed on your home, typically close to your main service panel or electric meter. Its primary function is to convert the direct current (DC) electricity generated by a string of solar panels into alternating current (AC), which is then distributed to your home appliances and the electrical grid.

The way solar panels are wired together in a string inverter system is crucial to understand. All the panels in a string are connected in series, meaning that the electricity generated by each panel flows through a single circuit to the inverter. This configuration has a significant implication: if there is an issue with one panel in the string, the energy production of all the panels connected in that string will be affected. For example, if one panel in the string is shaded and produces less energy, the output of all the other panels in the string will be reduced to match the performance of the shaded panel. This can lead to a decrease in the overall efficiency of the system.

Despite this limitation, string inverters are very popular for residential solar installations, especially for homes with simple, unshaded roofs. Typically, only one string inverter is installed for a residential system, making it a cost-effective and straightforward solution. The simplicity of the setup and the proven reliability of string inverters have made them a favored choice for many homeowners and installers.

To address the limitations of string inverters and meet electrical code standards, they are often paired with DC power optimizers. Power optimizers are small devices attached to the back of each solar panel. They monitor and track the panel’s peak output, optimizing the performance of each individual panel. By regulating the voltage before the power is sent to the string inverter, power optimizers can maximize the amount of energy the system produces and mitigate the effects of shading. This means that even if one panel is partially shaded, the other panels can still operate at their maximum efficiency, reducing the overall impact on the system’s performance.

Microinverters

Microinverters perform the same basic function as string inverters, but they are installed underneath each solar panel on your roof. Some microinverter models are designed to handle two or four panels per unit, offering flexibility in system design.

With a microinverter, the conversion from direct current (DC) to alternating current (AC) is completed right at the back of the panel. This localized conversion is a key difference from string inverters, where the conversion happens at a central location. By placing the inverter directly at the panel, microinverters ensure that the electricity is converted immediately, minimizing energy loss and improving overall system efficiency.

One of the primary advantages of microinverters is that they function in a parallel circuit, rather than a series circuit like string inverters. In a string inverter system, the electricity production of each panel is capped by the performance of the lowest-producing panel in the string. If one panel is shaded or underperforming, it can significantly reduce the output of the entire string. Microinverters, however, do not have this issue. Each panel and microinverter combination operates independently, allowing each panel to “do its best” and contribute as much power as it can, regardless of the performance of other panels.

This independence is particularly beneficial for complex solar installations, such as those on multiple roof faces or with varying orientations and angles. For example, if you have some panels facing east and others facing south, microinverters can optimize the performance of each panel, ensuring that they all operate at their maximum efficiency. This is especially useful in situations where shading is a concern, as microinverters can isolate and mitigate the impact of shaded panels on the overall system performance.

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PIKESTEC specializes in designing, researching, developing, producing, and servicing solar photovoltaic mounting systems. Our systems can be installed on tile roofs, flat roofs, ground installations, carport solar mounting systems, and more. You can contact us for more information!