Solar Simulation System with Realistic Daily Solar Movement

As early as 2010, BF Engineering developed and implemented the world’s first solar simulation system in which the entire luminaire field moves in an arc around the vehicle, thereby reproducing the natural movement of the sun throughout the day. The innovative system concept was originally developed for a climatic wind tunnel at Mercedes-Benz and subsequently formed the technological basis for further international projects – including SAIC Motor in Shanghai, China. The SAIC system was explicitly designed based on the arc-shaped system previously implemented at Mercedes-Benz in Sindelfingen.

The heart of the system is a large-scale arc frame on which the complete luminaire field can be motorised and moved from one side of the vehicle, over the roof, to the opposite side. The solar position can be continuously adjusted over an angular range of −85° to +85°. This allows the direction of irradiation to be continuously changed during a test and enables an entire daily solar cycle – from the low solar position in the morning through midday sun to sunset – to be simulated under reproducible laboratory conditions.

Unlike conventional static solar simulation, this means that not only the irradiation intensity but also the actual angle of incidence of the radiation on the vehicle changes. Doors, glazing, roof, bonnet, rear section and interior are thermally loaded from different directions depending on the simulated solar position. In addition, the front and rear sections of the luminaire field can be tilted by up to 45° to specifically irradiate the front and rear areas.

For the follow-up project at SAIC, the technology was implemented with 28 BF SUN luminaires rated at 4,000 W each. The system achieves an irradiance of up to 1,200 W/m² on a reference area of 6 × 2.5 metres, with a homogeneity of better than ±10%. The system is designed for vehicles up to 6 × 2.5 × 2 m and generates a global spectrum according to Air Mass 1.5.

Freely programmable positions and power levels allow defined solar positions as well as complete irradiation profiles to be stored and reproduced. Six pyranometers record the actual irradiance. This makes the system particularly suitable for demanding investigations of thermal management, air conditioning, vehicle interiors and temperature-sensitive components over a realistic daily solar cycle.

The arc-shaped system therefore combines high irradiation power with exceptional mechanical freedom of movement and transfers the natural movement of the sun into a controllable laboratory environment. The concept, first implemented in 2010, and the subsequent international systems demonstrate BF Engineering’s long-standing expertise in the development of customised solar simulation systems.