Renesas and Eggtronic Launch 500W GaN Solar Microinverter Reference Design with 96.1% Efficiency

 

Introduction

As residential and commercial solar installations continue to grow, photovoltaic (PV) modules are becoming more powerful, with many modern panels now delivering over 400 W of output. This increase in panel power has created demand for next-generation microinverters that can handle higher power levels while maintaining excellent efficiency, compact size, and long-term reliability.

To address these requirements, Renesas Electronics and Eggtronic jointly introduced the ERD00718 500 W Solar Microinverter Reference Design in June 2026. The platform combines Eggtronic’s proprietary EPIC™ mixed-signal control technology with Renesas’ TP65B110HRU bidirectional Gallium Nitride (GaN) switch, creating a high-efficiency single-stage DC-to-AC conversion architecture for modern photovoltaic systems.

Unlike a commercial end product, this is a reference design that solar equipment manufacturers can evaluate and use as the foundation for developing their own next-generation microinverters.

 

What Has Been Announced?

The collaboration introduces a 500 W continuous-output solar microinverter reference platform designed for high-power PV modules.

Some of the headline specifications include:

·         500 W continuous output power

·         Single-stage DC-to-AC conversion topology

·         Renesas TP65B110HRU bidirectional GaN power switch

·         Eggtronic EPIC2ACO01 mixed-signal controller

·         Up to 96.1% average CEC efficiency

·         95.9% average EU efficiency

·         Switching frequencies up to 1 MHz

·         Total Harmonic Distortion (THD) below 3%, meeting IEEE 1547 grid-interconnection requirements.

These specifications demonstrate how advanced control algorithms and wide-bandgap semiconductors can improve both efficiency and power density.

 

Understanding a Solar Microinverter

A microinverter converts the DC power generated by a single solar panel into grid-compatible AC power.Unlike traditional string inverter systems, where multiple panels share one inverter, each panel has its own dedicated microinverter.

Conventional String Inverter

Panel 1
Panel 2  ---> One Central Inverter ---> Grid
Panel 3
Panel 4

Microinverter System

Panel 1 ---> Microinverter ---> Grid
Panel 2 ---> Microinverter ---> Grid
Panel 3 ---> Microinverter ---> Grid
Panel 4 ---> Microinverter ---> Grid

This architecture allows every panel to operate independently.

 

Why Are Microinverters Becoming Popular?

Microinverters solve several limitations of conventional string inverters.

Higher Energy Harvest

If one panel is partially shaded in a string inverter system, the performance of the entire string can decrease.

With microinverters:

·         each panel performs its own Maximum Power Point Tracking (MPPT),

·         shading affects only the impacted panel,

·         overall energy production increases.

Better Reliability

A failure in one microinverter affects only a single solar panel rather than the entire array.

Improved Monitoring

Because each panel has its own inverter, installers can monitor:

·         panel voltage,

·         output power,

·         efficiency,

·         fault conditions,

at the individual panel level.

 

Why Is This Reference Design Different?

The Renesas–Eggtronic design introduces several technologies that distinguish it from many conventional microinverter architectures.

Single-Stage DC-to-AC Conversion

Many microinverters use a two-stage approach:

1.    DC-DC boost converter

2.    DC-AC inverter

The new platform instead performs the conversion using a single-stage AC Dual Active Bridge (AC-DAB) cycloconverter topology, reducing component count and eliminating a large intermediate DC-link stage. This helps lower switching losses, reduce BOM cost, and simplify the power path.

 

Gallium Nitride (GaN) Power Device

The reference design uses Renesas’ TP65B110HRU bidirectional GaN switch.

Compared with conventional silicon MOSFETs, GaN devices provide:

·         lower switching losses,

·         faster switching speeds,

·         reduced gate charge,

·         higher-frequency operation,

·         improved efficiency,

·         smaller magnetic components.

Operating efficiently at frequencies approaching 1 MHz allows designers to reduce the size of transformers and inductors, increasing overall power density.

 

EPIC Mixed-Signal Controller

At the heart of the design is the EPIC2ACO01 mixed-signal controller developed by Eggtronic.

The controller implements:

·         Variable Frequency Modulation (VFM)

·         Current-mode control

·         Continuous Zero-Voltage Switching (ZVS)

Maintaining ZVS across the full operating range significantly reduces switching losses and thermal stress, improving overall converter efficiency and reliability.

 

Key Technical Highlights

1. High Efficiency

The platform achieves:

·         96.1% average efficiency (CEC)

·         95.9% average efficiency (EU)

For residential solar systems operating for decades, even a 1% improvement in conversion efficiency can translate into a substantial increase in total energy delivered over the system’s lifetime.

2. High Switching Frequency

Operating at up to 1 MHz enables:

·         smaller inductors,

·         smaller transformers,

·         reduced PCB area,

·         higher power density.

3. Low Harmonic Distortion

The design maintains THD below 3%, supporting compliance with IEEE 1547 requirements for grid-connected distributed energy resources.

 

Benefits for Solar Equipment Manufacturers

Because this is a reference platform rather than a finished product, manufacturers can use it to shorten development time.

Potential benefits include:

·         Faster product development

·         Lower engineering risk

·         Proven high-efficiency architecture

·         Reduced component count

·         Improved thermal performance

·         Compact PCB layouts

·         Easier certification

Reference designs also allow engineering teams to focus on product differentiation instead of starting with a completely new power stage.

 

Industry Impact

The announcement reflects several broader trends in power electronics.

Manufacturers are increasingly adopting:

·         Gallium Nitride (GaN) power semiconductors,

·         high-frequency switching,

·         advanced digital control,

·         integrated reference platforms.

Together, these technologies enable smaller, lighter, and more efficient power converters for renewable energy systems.

As solar installations continue to grow worldwide, demand for compact, high-efficiency microinverters is expected to increase, particularly for residential and commercial rooftop applications.

 

Designer’s Perspective

For power electronics engineers, this reference design is especially interesting because it demonstrates how wide-bandgap semiconductors and advanced control algorithms can simplify converter architectures.

A single-stage topology operating at high frequency is not easy to implement. Achieving stable control, low THD, and ZVS across varying irradiance and load conditions requires sophisticated modulation and careful magnetic design. The combination of a bidirectional GaN switch with Eggtronic’s digital control approach illustrates how modern semiconductor technology can reduce system complexity while maintaining high efficiency.

The design also highlights an industry direction that extends beyond solar applications. Similar high-frequency GaN-based architectures are increasingly being adopted in EV chargers, server power supplies, battery energy storage systems, and industrial power converters.

 

Conclusion

The ERD00718 500 W Solar Microinverter Reference Design from Renesas and Eggtronic demonstrates how GaN power devices, mixed-signal digital control, and single-stage conversion can improve the efficiency and compactness of next-generation photovoltaic systems.

By achieving 96.1% CEC efficiency, operating at switching frequencies up to 1 MHz, and maintaining low harmonic distortion, the platform provides manufacturers with a practical foundation for developing advanced microinverters that support modern high-power solar panels.

As renewable energy systems continue to evolve, reference designs like this are likely to accelerate innovation by reducing development time while showcasing the capabilities of advanced semiconductor technologies.