Solar Radiation Testing

Scope

Solar radiation testing covers the controlled exposure of products and materials to a simulated solar spectrum in an environmental chamber, to evaluate both the heating (solar load) effect and the actinic (photodegradation) effect, principally per MIL-STD-810 Method 505.

Key aspects of the test scope include:

• Heating (solar load) procedure – applying a realistic solar spectrum at controlled intensity, typically in a diurnal (day/night) cycle, to determine the elevated temperatures produced in and on the product
• Actinic (steady-state) procedure – longer exposure emphasizing the UV-driven photochemical degradation of materials over time
• Solar spectrum – a source and filtering arranged to approximate the spectral distribution of natural sunlight across UV, visible, and infrared
• Intensity and cycling – controlled irradiance (commonly around 1120 W/m² peak for the standard cycle) applied steadily or in 24-hour cycles, with chamber temperature control
• Measured effects – internal/surface temperature rise (heating) and material changes such as fading, color change, embrittlement, cracking, chalking, and loss of properties (actinic)
• Related standards – MIL-STD-810 Method 505 (primary); related accelerated weathering standards (e.g., ASTM G155/D4459 xenon-arc) where long-term durability is the focus

Applications

• Military and defense equipment – qualifying equipment per MIL-STD-810 Method 505 for the solar environments it will face in deployment, both heating and degradation
• Aerospace – evaluating solar loading and UV degradation of aircraft and aerospace components and materials exposed to sunlight
• Outdoor electronics and enclosures – determining the internal temperature rise from solar heating in outdoor electronic enclosures, and the UV durability of their housings
• Automotive – assessing solar heating of interiors and components and the UV degradation of exterior and interior materials
• Polymers, coatings, and elastomers – evaluating fading, chalking, embrittlement, and property loss in materials exposed to the UV content of sunlight
• Textiles and consumer products – assessing color fastness and material durability of products used outdoors
• Product temperature/safety assessment – determining whether solar heating pushes a product beyond safe or functional temperature limits

Benefits

• Captures both heating and degradation – Method 505 addresses the two distinct solar effects (elevated temperature and photochemical degradation), so a single testing capability evaluates both how hot a product gets and how its materials deteriorate
• Realistic solar spectrum – using a spectrum matched to natural sunlight makes the results representative of true outdoor exposure rather than an arbitrary light source
• Reveals solar-load temperatures air-temperature testing misses – solar heating can drive product temperatures well above ambient; the test quantifies this, which plain temperature testing does not
• Identifies UV-vulnerable materials before deployment – actinic testing reveals fading, embrittlement, and property loss before products reach the field, guiding material selection and protection
• Supports equipment qualification – Method 505 results provide the evidence needed to qualify equipment for solar environments, particularly in military and aerospace programs
• Complements weathering and temperature programs – fits alongside accelerated weathering and temperature testing to build a complete picture of outdoor environmental durability