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Microinverters: Benefits, Comparison to Others & Innovations

Tracing their history back to the work by Werner Kleinkauf at the ISET in the 1980s, microinverters are one young solar inverter technology but have experienced tremendous technological leaps over recent years.

These inverters bring in many benefits to the solar industry, making solar more compelling while contributing to the energy transition.

What Are Microinverters & How Do They Work? 

Similar to solar optimizers, microinverters are classified as one type of module-level power electronics (MLPEs) that function at the side of individual solar panels.

Microinverter Installed On the Back of Panel
"Geek Hill solar electric project" (cropping) by Steve Rider old guy is licensed under CC BY-NC 2.0 DEED

They take the DC power produced by the solar panel they connect to and convert it into AC power. This process involves the combination of the maximum power point tracking (MPPT) technology to ensure that each panel operates at its maximum output. They adjust the voltage and frequency to match the requirements of household appliances or the power grid.

During the process, most modern microinverters leverage their built-in monitoring and communication capabilities to collect multidimensional real-time performance data of the panel. The data are then stored and processed in either a central monitoring hub at the site or the ‘cloud’. System owners or operators can access real-time visual data of individual panels and troubleshoot any underperformance or faults.

Additionally, according to the size of the system and particular applications, there are single-phase and three-phase microinverters. The former are geared toward residential applications which hold a market share of over 90%, while the latter are for commercial and industrial use.

Microinverters vs. Other Inverter Technologies

Microinverters boast many remarked advantages over traditional solar inverters.

Microinverters vs. String Inverters

In a string inverter solar project, all solar panels are connected in series and attached to the central string inverter. All DC power generated by the panels flows within the series circuit and then is aggregated into the string inverter for the DC-AC conversion process. 

Although the MPPT technology is usually utilized in the inverter, the overall efficiency and output are lower than that in a microinverter solar project. Because the string inverter cannot perform power optimization starting right from the sources and it is more vulnerable to any underperformance of individual panels owing to shading effect or other malfunctionings.

Microinverters vs. String Inverters With Optimizers

How do microinverters stack up against string inverters paired with solar optimizers?

Typically regarded as an improved version of string inverters, string inverters with optimizers add panel-level power optimization and monitoring capabilities to the system. Holding off discussion on cost and maintenance, these inverters are also effective means to mitigate shading and hotspot effects especially for residential projects.

However, they cannot break free from the constraints of the central string inverter. This leads to less flexibility in the expansion for the system. The high-voltage DC wiring from the optimizers to the inverter also poses a risk of safety issues, similar to the case of a standard string inverter project.

With their ‘two-in-one’ design, microinverters combine optimization and conversion into a single unit, maximizing overall efficiency and output while providing flexibility and improving safety.

Rounding Up the Pros and Cons

We’ve prepared a round-up of the pros and cons of microinverters, to help you comprehend microinverters and weigh up if they are a better choice.

Pros of Microinverters

  • Improved Efficiency & Production: Microinverters work on a per-panel basis. They optimize and convert power for each individual panel. This leads to less impacts of affected neighboring panels on overall system efficiency and production. They are ideal for installations with frequent shadings or varying panel orientations. 
  • Robust Monitoring Capability: Their built-in monitoring module allows system owners to track the performance of each individual panel with ease using mobile apps. Detailed monitoring can help in promptly identifying specific issues or inefficiencies in the system, for easier and more precise maintenance on the routine.
  • Elevated Flexibility & Scalability: In contrast to other inverter options, microinverters provide great flexibility in system design and expansion. Additional panel with a paired microinverter can be easily added to the system without the potential need for a string inverter replacement.
  • Enhanced Reliability & Warranty: Many modern microinverters come with a longer lifespan warranty of up to 25 years. This matches the lifespan of solar panels and hence provides a more manageable warranty for the system, and peace of mind regarding long-term reliability and performance.
  • Upgraded Safety: Microinverters operate at lower voltages compared to string inverters, reducing the risk of high-voltage DC arcing and potential fire hazards. Their built-in rapid shutdown capability for detected faults or other emergency situations enhances safety for workers; on the other hand, adds another layer of flexibility for the system.
Panel-Level Monitoring Capability by Microinverters

Cons of Microinverters

  • Higher Upfront Cost: Considering the range of benefits provided, microinverters generally come with a higher upfront cost than other inverters. But if their long-term performance benefits outweigh the upfront cost, this is not sufficient to be considered a drawback.
  • Relatively More Complex Installation & Maintenance: Since a microinverter is installed for each panel, the installation process can be more time-consuming than installing a single string inverter. Beyond this, there is one inverter on each panel; this translates to more potential points of failure, increasing the likelihood of maintenance issues over time. But as many products are backed by 25 year warranty and as they enable speedy troubleshooting for underperforming panels, this does not appear like a big issue.

Innovations in Microinverters

Ongoing research is being conducted to further optimize the performance, reliability and integration capabilities of microinverters.

Enhancing the grid-connected capability and adaptability is one of the focal points. The transformerless buck-boost inverter technology has undergone constant refinement. It can smartly step down and step up voltage to match the required output voltage. When integrated into microinverter products, it can enable greater flexibility in system design and grid-connected applications. For the sake of greater flexibility and adaptability, Enphase’s IQ8 Series microinverters also integrate their proprietary application-specific integrated circuit (ASIC) to allow easy switching between grid-tied and off-grid modes.

Moreover, microinverters will be more intelligent. Manufacturers utilize more advanced microchips with high-speed digital logic and super-fast response times to handle changing loads and grid events, which on the flip side can eliminate limitations on battery size for solar-plus-storage systems. 

Building upon robust computing capability, microinverters can somehow function like AI, constantly learn from the panel's output voltage at each AC cycle and decide which conversion strategy should be performed for the next conversion procedure. This further boosts efficiency and helps capture more energy in low-light conditions.

Are Microinverters a Better Choice?

Whether microinverters are a better choice for your project comes down to several considerations. Beyond on-site surveys regarding space, climate, irradiation, shading and the like, you should factor into installation and maintenance. 

Fusing more flexibility, reliability, scalability as well as intelligence into a compact unit turns out to be a mainstream trend in the solar inverter market. For many, the major downside may be their higher price tag. But, especially if you zoom in on long-term savings, microinverters are definitely worth your investment.

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