In 2012, COLAS, the worldwide leader in the bitumen and road coatings sector, has decided to equip one of its regional sites with a solar thermal installation for temperatures up to 200°C. Coupled with a gas boiler, the solar collectors were installed with the dual purpose of meeting the thermal energy needs of a workshop building and to maintain two bitumen storage tanks above its melting point. This article gives a short description of the heating system at this industrial site and of its operating modes. It also describes the numerical model developed for detailed system simulation. First simulation results give a low annual solar heat gain of 94.6 kWh/m2 which is 2.6 times lower than initial estimations. Further investigations will be performed during the ongoing project in order to optimize the solar heat gain and to identify the reasons for this unsatisfactory result.