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Case Study: Solid-State Thermal Solution for Solar Micro-Inverters

On | By T-Global USA

Case Study: Solid-State Thermal Solution for Solar Micro-Inverters

Contents

 

In residential solar energy systems, a North American solar equipment manufacturer implemented a solid-state thermal management system using T-Global’s XL-25D ceramic heat spreaders and TG-A3500 thermal pads to improve heat dissipation from power transistors in solar micro-inverters. This technical approach, applied during an active design-iteration phase, allowed for more efficient prototyping by facilitating rapid design changes, enabling straightforward field replacement of components, and supporting low-volume customization, thereby reducing risk before mass production.

 

What Is a Solar Micro-Inverter?

A solar micro-inverter is a small power-conversion device installed on or near an individual solar panel, rather than routing an entire array through one central inverter. Each micro-inverter converts the direct current (DC) power produced by its own dedicated panel into grid-compatible alternating current (AC) power right at the panel. This architecture is often called panel-level power conversion.

This is one of two dominant inverter architectures used in residential solar systems, alongside traditional string inverters, which convert DC to AC for an entire series-connected string of panels from a single central location, typically mounted at ground level or on an exterior wall. (Solar Inverter Types: String, Micro, and Hybrid Inverters Explained, 2026)

 

  • Panel-level optimization: If one panel is shaded or underperforming, it doesn’t drag down the output of the whole string, since each panel converts power independently.
  • Simplified system design: No separate central inverter enclosure is needed; conversion hardware is distributed across the array.
  • Panel-by-panel monitoring: Many systems report performance data for each panel, making it easier to spot underperformance.
  • Lower rooftop DC voltage: Because conversion happens locally at each panel, DC voltage on the roof stays low, which can simplify code compliance and improve safety.

 

💡READ MORE: Recent news from leading micro-inverter suppliers shows how fast the residential segment is evolving. Enphase has pushed higher-power rooftop systems forward with its new IQ9N residential microinverter, first launched in Europe and then introduced in the U.S., with GaN-based power electronics aimed at improving efficiency and thermal performance.

 

Why Thermal Management Is Critical for Micro-Inverters

Residential micro-inverters operate continuously outdoors, where elevated ambient temperatures, direct solar loading, and sealed IP-rated enclosures all work against heat dissipation. These demanding conditions also expose materials to UV radiation, moisture, and repeated temperature cycling, so choosing components with proven outdoor durability is essential for long-term reliability. Power transistors, magnetics, and control circuitry are packed into a compact footprint, and each of these components generates heat during normal operation, with fewer places for that heat to escape than in a ventilated, ground-mounted central inverter cabinet (Analyzing Microinverter Reliability: Heat Dissipation Techniques, 2026).

Long-term thermal stability directly affects power conversion efficiency, component lifetime, and overall system reliability. That is why effective thermal management has to be built into the design from the start, not addressed after the fact (Afridi et al., 2023).

This is exactly the environment one T-Global customer was designing for.

 

The Challenge: A Flexible Thermal Approach for an Evolving Design

The customer is a solar equipment manufacturer based in North America, working in the energy sector on micro-inverters for residential solar systems. As they worked through their design, they needed a thermal approach that could keep pace with an evolving layout, one that would support design revisions and product validation without adding rework costs or slowing the schedule.

 

The Objective

The objective was to achieve reliable heat dissipation while allowing rapid design iterations, as component layouts and heat source locations continued to evolve throughout development. For that stage of the project, they wanted a flexible, solid-state thermal solution that could:

  • Adapt to different heat source locations across the circuit board as the design evolved.
  • Work within tight, fixed structural space constraints inside the enclosure.
  • Meet long-term reliability requirements for outdoor, roof-mounted residential installations.
  • Allow components to be installed, adjusted, or replaced quickly during prototyping and design validation.

 

The Solution: A Two-Part Solid-State Thermal Management System

The Solution: A Two-Part Solid-State Thermal Management System | T-Global USA

T-Global engineered a modular, solid-state alternative built around the TO-220 power transistor, a common package for the switching devices used in micro-inverter power stages. The system pairs a ceramic heat spreader with a thermal pad, giving the customer a stack that conducts heat efficiently while remaining fully field-adjustable.

 

The Thermal Conduction Path

The Thermal Conduction Path | T-Global USA

Heat generated at the power transistor needs a clear route out of the enclosure. In this design, it moves in stages: from the power transistor (the heat source), through the ceramic heat spreader (acting as an electrical insulator), through the thermal pad (which fills the surface irregularities between the heat spreader and the enclosure), into the aluminum enclosure (which acts as the heat sink), and finally out into the surrounding ambient air.

 

Why the Combination Works

The ceramic heat spreader and thermal pad aren’t interchangeable: each plays a distinct, complementary role along that path. The ceramic heat spreader redistributes concentrated heat away from the power transistor while providing electrical isolation and long-term thermal stability. The thermal pad then conforms to surface irregularities between the spreader and the aluminum housing, minimizing interface resistance and enabling efficient heat transfer into the enclosure. Together, the two materials create an efficient thermal path from the power semiconductor to the aluminum housing.

 

XL-25D / XL-25W Ceramic Heat Spreader

XL-25D / XL-25W Ceramic Heat Spreader | T-Global USA

The ceramic heat spreader sits directly against the power device and spreads heat locally before it reaches the pad and heatsink. Key attributes include:

  • Spreads localized heat: Draws heat away from concentrated hot spots on the board.
  • Low thermal expansion: Maintains dimensional stability across temperature cycling.
  • Electrical isolation: Protects against short circuits between the power device and grounded metal enclosure.

Because it is a solid, discrete component rather than a poured compound, engineers can reposition, swap, or resize the ceramic spreader as the board layout changes. For example, if thermal testing during prototyping reveals the need to relocate a power transistor, engineers can easily move or replace the heat spreader without removing cured material or undertaking time-consuming rework. This flexibility represents a significant advantage during the prototyping and design-validation phase.

Tailored Dimensions for Standard Power Device Packages

The XL-25D/XL-25W ceramic heat spreader is available pre-sized to match industry-standard power device packages, so it drops into existing designs without custom tooling:

Packaging Spec. Dimensions (mm)
TO-220 20 x 14 x 0.635
TO-220 20 x 14 x 1.0
TO-220 12 x 18.5 x 1.0
TO-247 22 x 17 x 0.635
TO-247 22 x 17 x 1.0
TO-264 28 x 22 x 0.635
TO-264 28 x 22 x 1.0
TO-3P 25 x 20 x 0.635
TO-3P 25 x 20 x 1.0

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TG-A3500 Thermal Pad

TG-A3500 Thermal Pad | T-Global USA

The TG-A3500 thermal interface pad completes the stack, sitting between the ceramic spreader and the aluminum enclosure. Key characteristics include:

  • Reliable thermal contact: Maintains consistent contact across the interface under normal operating conditions.
  • Low interface resistance: Minimizes the resistance heat encounters as it crosses from the spreader into the enclosure.
  • Tolerance compensation: Its selectable thickness range absorbs manufacturing and assembly tolerances between components.

TG-A3500 thermal pad key properties:

Property Value
Thermal Conductivity 3.5 W/m·K
Thickness 0.5 – 8.0 mm
Dielectric Breakdown Voltage 13 kV/mm
Hardness Shore OO 35

 

The real driver of flexibility is T-Global USA’s post-process customization: We offer services to die-cut, kiss-cut, or film-cut pads to precise shapes for a given board layout. We also provide reinforcement options with fiberglass mesh for added stability in high-power applications. Additionally, engineers can choose from PET or PI lamination, liner, and adhesive configuration to match assembly and handling requirements. Together, this lets engineers close varying air gaps caused by component tolerances or enclosure design changes, and adapt the pad to a new revision, without redesigning the thermal stack from scratch.

REQUEST A QUOTE OR SAMPLE

 

Key Benefits & Core Value

Key Benefits

Solid-state Thermal Solution: A fully solid-state stack delivers reliable heat transfer while remaining adjustable throughout development.

Rework-Friendly Assembly: Because components aren’t cured or bonded in place, installation and design rework stay simple, even late in the design cycle.

Design Iteration Flexibility: The stack supports changing component layouts and heat source locations as thermal requirements evolve.

 

Core Value

De-risked Development: Because the components are discrete and installed rather than cured in place, design teams can validate thermal performance early in the development cycle, catching problems before they reach mass production.

Localized & Custom Agility: The solid-state stack supports low-volume customization and responsive technical support. Engineers can quickly adjust heat spreader placement or pad thickness for a specific board revision, without a long lead time.

Accelerated Time-to-Market: Streamlined material adoption (dropping in a standard-sized ceramic spreader that matches common power device packages, paired with a thermal pad sized to fit) helps manufacturers move from prototype to production faster.

 

Why This Customer Chose a Solid-State Approach for This Stage of Development

For power electronics like solar micro-inverters, where heat source locations and enclosure geometry are still being finalized, a solid-state ceramic spreader combined with thermal pad system offers three practical advantages during active design work:

  1. Reversibility: Engineers can remove, reposition, or replace components during rework and testing.
  2. Design iteration speed: Engineers can change the thermal path as the layout evolves, without waiting on a new production cycle.
  3. Electrical safety margin: Ceramic spreaders provide electrical isolation, and the TG-A3500 thermal pad offers a 13 kV/mm dielectric breakdown voltage rating, supporting the insulation requirements of high-voltage power stages.

Once a design is finalized, with the circuit layout and component positions locked down, and production volumes begin to scale up, it typically makes sense to switch from a solid-state solution to potting compounds. Potting compounds are an excellent option for permanently sealing and protecting an assembly against moisture, vibration, and environmental exposure. In general, engineers should consider this transition when the design has passed validation, further changes are unlikely, and consistent high-volume manufacturing is the next step. T-Global offers both solid-state thermal materials and potting compounds, so manufacturers can choose the right material for wherever their product is in its development lifecycle.

 

FAQs

What is a solid-state thermal solution?

A solid-state thermal solution uses discrete, pre-formed components, such as ceramic heat spreaders and thermal pads, to move heat away from electronic components. Because the parts aren’t cured or bonded in place, engineers can reposition, resize, or replace the components as a design evolves.

 

When should you use a ceramic heat spreader and thermal pad system in a solar micro-inverter?

A ceramic heat spreader and thermal pad system is well suited to the design and validation phase, when component placement, heat source locations, or enclosure geometry may still change. Because the parts are discrete rather than cured in place, engineers can modify the thermal path quickly during development, helping reduce both cost and time-to-market ahead of finalizing a production design.

 

What power device packages does T-Global’s thermal solution support?

The XL-25D/XL-25W ceramic heat spreaders are available in dimensions for standard power packages, including TO-220, TO-247, TO-264, and TO-3P.

 

What post-process customization options does T-Global offer for thermal pads?

T-Global offers a range of post-process services for thermal gap fillers, including multiple cutting methods, reinforcement options, lamination choices, liner selection, adhesive configuration, and custom labeling and packaging, so thermal pads can be tailored to a specific application rather than used as generic sheet stock.

 

Talk to T-Global About Your Thermal Design Challenge

Whether you’re developing solar micro-inverters, EV power electronics, or any application where heat source locations and enclosure space continually change during development, T-Global’s thermal materials provide the flexibility to iterate rapidly at any stage. When your design progresses to the production phase, potting compounds are available to help seal and protect the finished assembly.

 

References

TAGS: Ceramic Heat Spreader Micro-inverter Heat Dissipation Solar Micro-inverter Thermal Management Solid-state Thermal Solution Thermal Pad for Power Electronics TO-220 Thermal Management