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New Solar Panel Glass Coating Could Improve Light Transmission and Cooling

Researchers have developed a porous silicon dioxide coating for solar panel glass that could reduce reflection and improve passive heat release, potentially helping future PV modules use sunlight more effectively.

News report · August 22, 2026 · 7 min read

Solar panels need sunlight to generate electricity, but not all of the sunlight that reaches a module becomes useful electrical energy.

Some incoming light is reflected by the front surface of the panel, while a large amount of absorbed solar energy eventually becomes heat. Higher solar-cell temperatures can reduce photovoltaic power output, which is why researchers continue to study new ways to improve both light transmission and thermal management.

A research team from Germany and Namibia has now developed a porous silicon dioxide (SiO₂) coating for photovoltaic cover glass that is designed to address both problems at the same time.

The experimental coating increased solar transmittance while also improving the glass's ability to emit thermal radiation in the mid-infrared range.

The research is still at an early stage, but it could point toward future solar-module glass that allows more sunlight to reach the cells while helping the module release heat more effectively.

What Did the Researchers Develop?

The researchers created a porous silica coating intended for the glass covering photovoltaic modules.

Solar-panel cover glass already performs several important functions. It protects the cells from weather and physical damage while allowing sunlight to pass through to the photovoltaic material underneath.

However, part of the incoming sunlight can be reflected at the glass surface.

Anti-reflective coatings are therefore used in photovoltaic and other optical applications to reduce reflection and allow more useful light to pass through.

The new research adds another goal: passive radiative cooling.

Instead of focusing only on reducing reflection, the coating was designed to improve the ability of the glass to release thermal energy as infrared radiation.

This means one material could potentially help address two different performance losses:

  • Front-surface reflection
  • Heat accumulation in the module

The researchers used porous silicon dioxide because its microscopic structure can be engineered to influence how the surface interacts with both incoming sunlight and outgoing thermal radiation.

How Much More Sunlight Passed Through the Glass?

According to the research reported by pv magazine, the strongest overall balance came from a two-layer porous silica coating containing 0.40 g of the pore-forming material Pluronic F127.

That coating achieved approximately 91.0% solar transmittance.

The uncoated reference glass reached approximately 89.8% solar transmittance.

That is an increase of about 1.2 percentage points in the amount of solar radiation transmitted through the glass.

A single-layer version of the coating also reached around 90.9% to 91.0% transmittance.

This improvement may appear small, but solar-module engineering often involves reducing many small losses that occur between incoming sunlight and the electricity delivered by a PV system.

More light reaching the photovoltaic cells can potentially increase photocurrent, provided that the rest of the module can make use of the additional transmitted solar energy.

Could the Coating Increase Solar Panel Efficiency?

The researchers estimated what the optical improvement might mean for a hypothetical PV module.

If photocurrent increased approximately in proportion to the additional transmitted sunlight, they calculated that a solar module operating at 20% efficiency could potentially gain about 0.25 percentage points of absolute efficiency, increasing from around 20% to approximately 20.25%, from the optical improvement alone.

This is an estimate rather than a measured module-level result.

The coating has not yet been demonstrated to increase a commercial solar panel from 20% to 20.25% efficiency under real-world conditions.

That distinction is important.

The current work focused on the optical and thermal behavior of coated glass. The next stage is expected to involve integrating the coating into complete PV modules and testing actual electrical output and operating temperature outdoors.

Why Solar Panel Temperature Matters

Solar panels can receive very strong sunlight while operating at temperatures significantly above the surrounding air temperature.

Although sunlight is necessary for electricity generation, higher photovoltaic cell temperatures generally reduce voltage.

The U.S. Department of Energy notes that solar cells typically perform better at lower temperatures. As temperature increases, current may rise slightly, but the reduction in voltage is usually larger.

This temperature effect is why solar-panel datasheets commonly include a temperature coefficient of power.

A module with a negative power temperature coefficient will produce less maximum power as its cell temperature rises above the reference test temperature.

This does not mean cold cloudy weather automatically produces more energy than a hot sunny day. Solar irradiance remains one of the biggest factors affecting PV output.

Instead, it means that for a given amount of sunlight, reducing excessive cell temperature can help limit temperature-related power losses.

How Passive Radiative Cooling Works

Passive radiative cooling is a way for a surface to release heat without requiring electricity-powered cooling equipment.

Objects naturally emit thermal radiation.

By engineering a surface to emit infrared radiation efficiently at useful wavelengths, some thermal energy can leave the surface as electromagnetic radiation.

For solar modules, this is attractive because an active cooling system could require:

  • Fans
  • Pumps
  • Plumbing
  • Additional electricity
  • Maintenance
  • More installation hardware

A passive coating would not need a motor or compressor to operate.

The new porous silica coating was therefore designed not only to transmit incoming solar radiation but also to improve mid-infrared thermal emission.

What Were the Cooling-Related Results?

The two-layer coating that provided the strongest overall balance reached approximately 90% mid-infrared emissivity.

The bare reference glass had around 87% emissivity.

Researchers also found that thicker coatings could increase emissivity even further.

Some configurations reached values as high as approximately 96%.

However, there was a trade-off.

Adding more coating material improved thermal emissivity but could reduce solar transmittance because additional scattering prevented some light from passing through the glass.

For photovoltaic use, maximizing only one property is therefore not enough.

A practical coating needs to find a balance between:

  • High solar transmittance
  • Low optical reflection
  • Strong thermal emission
  • Suitable thickness
  • Long-term durability
  • Manufacturing cost

The two-layer design was considered the strongest overall balance among the tested configurations.

How Was the Coating Made?

The researchers used a sol-gel process to produce the silica coating.

Low-iron soda-lime glass was used as the substrate.

The research involved acid- and base-catalyzed silica sols, while Pluronic F127 was used as a template to help create the porous structure.

Several concentrations of F127 were tested.

The coating mixture was deposited onto glass by spin coating, with samples receiving up to three coating layers.

The coated samples were then heated to stabilize the porous silica structure and remove the organic template.

Researchers analyzed the materials and optical properties using techniques including:

  • Scanning electron microscopy
  • Fourier transform infrared spectroscopy
  • Spectrophotometry

These laboratory methods allowed the researchers to examine the coating structure as well as its transmission and thermal-emission behavior.

Why the Porous Structure Is Important

The pores inside the silica coating are not simply empty defects.

Their size and distribution help determine the optical properties of the material.

A properly designed porous layer can reduce the effective refractive index of the coating, which can reduce reflection at the air-glass interface.

At the same time, the material's structure can influence its infrared emissivity.

The challenge is that changing the thickness and microstructure can improve one property while making another property worse.

For example, a thicker coating may release thermal radiation more effectively but also scatter more incoming sunlight.

This is why the research focused on finding a coating structure that provides a useful compromise instead of simply maximizing coating thickness.

What Still Needs to Be Tested?

The research is promising, but several major questions remain before this type of coating could be considered for commercial solar panels.

Complete PV Module Testing

The coating needs to be integrated into actual photovoltaic modules.

Researchers then need to measure whether changes in transmittance and emissivity produce meaningful differences in:

  • PV cell temperature
  • Voltage
  • Current
  • Maximum power
  • Daily energy production

Outdoor testing is especially important because real solar modules experience changing irradiance, wind, humidity, clouds, and ambient temperature.

Long-Term Durability

Solar panels are commonly expected to operate outdoors for decades.

A front-glass coating would therefore need to survive exposure to:

  • Ultraviolet radiation
  • Rain
  • Humidity
  • Temperature cycling
  • Dust
  • Pollution
  • Wind
  • Cleaning
  • Abrasion

A coating that performs well in a laboratory but degrades quickly outdoors would have limited value for commercial photovoltaic modules.

Large-Area Manufacturing

Laboratory samples can be coated using controlled processes that may not be practical for mass production.

Commercial manufacturers would need a method capable of applying the coating consistently over large areas of solar glass at high production volumes.

The coating would also need to be inexpensive enough that any additional energy yield or performance benefit justifies the added manufacturing cost.

Could It Help With Solar Panel Soiling?

The researchers also plan to investigate possible anti-soiling effects.

Soiling occurs when dust, dirt, pollution, or other material accumulates on the surface of solar modules and blocks part of the incoming sunlight.

If a future version of the coating could combine:

  • Anti-reflection
  • Passive cooling
  • Improved light transmission
  • Anti-soiling behavior

it could potentially address several front-surface PV losses with one material.

However, anti-soiling performance should not be assumed from the current results.

It remains an area for further research.

Can Homeowners Apply This Coating to Existing Solar Panels?

No consumer-ready version of this experimental coating has been demonstrated in the research.

Homeowners should not interpret the study as a recommendation to apply silica products or other coatings to existing solar modules.

Commercial PV modules may already contain factory-applied surface treatments.

Adding an unapproved material could potentially affect:

  • Light transmission
  • Reflection
  • Cleaning
  • Surface durability
  • Manufacturer warranty conditions

Any coating intended for a solar module should be specifically engineered and tested for photovoltaic use.

For existing installations, owners should continue following the cleaning and maintenance instructions provided by the module manufacturer or installer.

Why This Research Is Interesting for the Solar Industry

Improving solar technology does not depend only on creating higher-efficiency photovoltaic cells.

A complete module contains many materials and components that influence how much electricity can ultimately be produced.

Performance can be affected by:

  • Front-glass reflection
  • Cell temperature
  • Electrical resistance
  • Cell interconnections
  • Encapsulation
  • Shading
  • Soiling
  • Module design

Even when the solar cells themselves remain unchanged, reducing losses elsewhere in the module can improve overall performance.

That is what makes the porous silica research interesting.

Instead of replacing the photovoltaic cell technology, it attempts to improve the environment in which the cells operate by allowing slightly more sunlight through the front glass while improving thermal radiation.

Is This a Solar Panel Breakthrough?

It is better described as promising photovoltaic materials research than as a finished solar-panel breakthrough.

The laboratory results show that the coating can change the optical and thermal characteristics of solar cover glass.

But several steps remain before its real-world value can be determined.

The research team plans to test the coating on complete PV modules outdoors and investigate scalable manufacturing, durability, and possible anti-soiling behavior.

Those tests will help answer the most important practical questions:

  • Does the coating meaningfully reduce module temperature outdoors?
  • Does it increase actual electrical energy production?
  • Can it survive years of weather exposure?
  • Can manufacturers apply it economically at large scale?

Until those questions are answered, the reported results should not be treated as guaranteed performance improvements for commercial solar panels.

What Happens Next?

The next stage of development is expected to focus on complete solar modules rather than coated glass samples alone.

If module-level tests confirm both higher light transmission and useful cooling, researchers can begin evaluating how much extra electricity the technology could produce over days, seasons, and years.

Large-area manufacturing will also be critical.

A coating that is effective on a small laboratory sample must eventually be applied uniformly to full-size solar-module glass if it is to become practical for industry.

Durability testing will be equally important because optical coatings on the front of solar modules are continuously exposed to the outdoor environment.

The Bottom Line

Researchers from Germany and Namibia have developed a porous silicon dioxide coating that combines anti-reflective behavior with passive radiative cooling for photovoltaic cover glass.

The strongest tested configuration achieved approximately 91.0% solar transmittance and 90% mid-infrared emissivity, compared with around 89.8% transmittance and 87% emissivity for the bare reference glass.

The results suggest that future solar-panel glass could potentially help more sunlight reach photovoltaic cells while also improving heat release.

However, the coating has not yet been proven to deliver the same gains in complete commercial solar modules.

Outdoor module testing, long-term durability studies, and scalable manufacturing research are still needed.

If those challenges can be addressed, the glass covering solar cells could become another important tool for improving future photovoltaic performance.

Sources