Solar Simulation
Source shaping for solar-cell testing and laboratory simulators.
Specialty optics & substrates
Air Mass Filters
Precision spectral shaping for solar simulation. OEM optical development tailored to your equipment and target solar spectrum.
Shape a solar-simulator source toward a target solar spectrum.
Explore models & spectra ↓
Related applications.
Research & Instrumentation
Spectral selection, beam paths and measurement systems.
PRODUCT MODELS & SPECTRA
Explore the measured response.
0 models in this collection.
Discuss the optical requirements for your project with our team.
Request for quote →SOLAR SIMULATION
The optical link
in solar simulation.
A solar simulator recreates selected characteristics of sunlight for controlled testing. Air Mass filters shape the source spectrum toward the chosen solar reference.
KUPO provides optical support for solar simulator equipment, with OEM filter research, development and custom design for different light sources, optical layouts and testing requirements.
Explore OEM development →
UNDERSTANDING AIR MASS
One sun.
Different spectral references.
Air mass describes the relative path sunlight travels through the atmosphere. Absorption and scattering change its spectral distribution before it reaches the ground.
BEYOND THE ATMOSPHERE
AM0
A reference for sunlight outside Earth’s atmosphere, before atmospheric filtering.
A spectral target for space solar-cell research and evaluation of photovoltaic devices intended for extraterrestrial conditions.
TERRESTRIAL SOLAR TESTING
AM1.5G
A terrestrial reference with an air mass of 1.5. The “G” means global irradiance, including direct and diffuse light on the reference tilted surface.
A widely used spectral target for evaluating solar cells and photovoltaic devices intended for operation on Earth.
AM0 and AM1.5G describe reference solar spectra, rather than a universal filter shape or a single wavelength.
WHY THE FILTER MATTERS
Shape the spectrum.
Support the measurement.
Balance the source output.
The lamp or light engine has its own spectral distribution. A filter selectively attenuates wavelengths to help bring that output closer to the required reference.
Design for the complete system.
The resulting spectrum depends on the source, filter, other optics and measurement plane. A passive filter cannot add wavelengths missing from the source; spectral matching is verified in the assembled simulator.
Source spectrum→Custom Air Mass filter→System optics→Measured output
APPLICATIONS
Optics for solar research
and equipment development.
Photovoltaic evaluation
Support controlled illumination for solar-cell and photovoltaic-device characterization against the selected spectral reference.
Space photovoltaics
Develop optical filtering around AM0 targets for space-oriented solar-cell research and evaluation.
Solar simulator OEMs
Integrate a source-specific filter into new equipment platforms, optical modules or simulator upgrades.
Laboratory development
Investigate spectral-response requirements and refine the optical design through prototype testing.
STANDARDS / KNOW THE DIFFERENCE
A reference spectrum.
A system classification.
Some standards define the sunlight to reproduce. Others define how to evaluate the complete solar simulator. Knowing the difference helps turn a project brief into a useful optical specification.
| Reference | What it addresses | What it means for your project |
|---|---|---|
| IEC 60904-9:2020 | Classification of solar simulators for terrestrial photovoltaic testing. | Evaluates spectral match, spatial non-uniformity and temporal instability. Includes A+, A, B and C classifications. |
| IEC 60904-3:2019 | PV measurement principles and terrestrial reference spectral irradiance. | Defines the reference light distribution used in the relevant PV measurement framework. |
| IEC 60904-7:2019 | Correction of spectral mismatch in PV testing. | Addresses differences between the test spectrum, reference spectrum and device spectral responses. |
| ASTM E927-19(2025) | Solar simulator classification for electrical performance testing of photovoltaic devices. | Evaluates the simulator’s spectral, spatial and temporal characteristics under the applicable test conditions. |
| ASTM G173-23 | Terrestrial reference solar spectra: direct normal and global irradiance on a 37° tilted surface. | The global reference supports AM1.5G spectral-target discussions. It is a reference spectrum, not an equipment certification. |
| ASTM E490-22 | Zero-air-mass reference solar spectral irradiance. | Provides an AM0 reference for applications such as space-oriented photovoltaic testing. |
| Japan: JIS C 8904-9:2017 Historical / withdrawn |
Former Japanese solar simulator performance requirements, following earlier references including JIS C 8912:1998. | Withdrawn on 20 December 2023. The Japanese Standards Association states that IEC 60904-9:2020 can be referenced without additional Japan-specific requirements. Identify the applicable edition in Japanese procurement documents. |
This is an original practical overview, not a reproduction of the standards. Confirm the specified edition, reference spectrum, wavelength intervals and measurement conditions for each project. Terrestrial classification requirements must not automatically be applied to an AM0 space-testing setup.
KUPO OPTICAL SUPPORT
Designed to support
AAA-class solar simulators.
KUPO develops source-specific Air Mass filters with spectral-matching capability of ±5% per agreed wavelength band for qualified equipment configurations. Our OEM development supports equipment teams working toward AAA-class simulator performance.
What does AAA describe?
AAA is commonly used to indicate Class A performance in three separate system characteristics. The applicable standard, edition, test area and measurement conditions must accompany the rating.
- Spectral match: how the output distribution compares with the reference.
- Spatial uniformity: how evenly the test area is illuminated.
- Temporal stability: how consistently the irradiance is maintained during measurement.
Where does the Air Mass filter contribute?
The filter shapes the spectrum and supports the spectral-matching requirement. Source control, beam-forming optics and the complete equipment design also determine uniformity and stability.
AAA is a simulator-level result verified on the assembled system, not a stand-alone filter certification. IEC 60904-9:2020 also defines A+; an AAA description should not be presented as the highest category in that edition.
UNDERSTANDING ±5%
Compare the energy share in each band.
For a band-integrated relative matching specification, compare each band’s share of the measured total with its share of the reference total over the same agreed wavelength interval.
Band match = measured band fraction ÷ reference band fraction
A ±5% relative tolerance means a band-match ratio of 0.95–1.05. For example, if a reference band contains 20% of the interval’s energy, a matching band fraction is 19–21%. This is an explanatory example, not a KUPO test result.
It does not mean ±5 percentage points, ±5% at every individual wavelength, or that the complete simulator has passed all three classification tests. The source, band definitions, normalization interval, angle and test-plane conditions are agreed during project review.
WHO WE SUPPORT
For the teams turning
solar light into reliable data.
Solar simulator manufacturers
OEM developers integrating Air Mass optics into new platforms, source upgrades and application-specific simulator designs.
University photovoltaic laboratories
Electrical engineering, materials science, applied physics and renewable-energy groups studying silicon, thin-film, perovskite and tandem solar cells.
National research & metrology laboratories
Teams developing reference measurements, calibration methods and spectral-mismatch studies. The filter supports the optical system; calibration traceability remains a separate laboratory responsibility.
PV manufacturers & test laboratories
Cell and module R&D, process development and performance-evaluation teams that need reproducible test illumination and a defined spectral target.
Space photovoltaic & aerospace teams
Research groups evaluating solar cells and materials under an agreed AM0 spectral reference, with optics developed for the intended test setup.
Materials & photochemistry research
University and industrial laboratories exploring solar-driven reactions or material response. Spectrum, irradiance and exposure must suit the experiment; a PV simulator classification alone does not validate an aging or photochemical test.
Application examples describe teams that may benefit from Air Mass optical development; they are not a list of KUPO customers or institutional endorsements.
WHY WORK WITH KUPO
One optical partner,
from target to integration.
Bring your source spectrum and equipment requirements to a team combining thin-film coating, in-house manufacturing and spectral inspection. We can develop the filter around your optical and mechanical constraints, evaluate prototypes and refine the design for OEM integration.
Whether you are building a university test bench or a simulator product line, start with your Air Mass reference, wavelength bands, source, beam geometry and required spectral match. We will help translate them into a measurable filter-development brief.
Discuss your Air Mass optical requirements →OEM / CUSTOM RESEARCH & DEVELOPMENT
Developed around
your equipment.
From a new solar simulator platform to a specific source-and-optics combination, KUPO can collaborate on custom Air Mass filter development.
01
Define the target
Share the Air Mass reference, wavelength interval, source spectrum and equipment objectives.
02
Design the optic
Review spectral shaping, substrate, coating, working angle, dimensions and thermal conditions.
03
Evaluate prototypes
Measure the filter and assess the spectral result in the intended optical system.
04
Refine for integration
Agree the final specification and mechanical interface, then plan OEM production requirements.
TECHNICAL RESOURCES