This paper presents the performance improvements implemented in the KTH high-flux solar simulator to deliver a total power on target closer to the working conditions of real CSP systems. Therefore, additional rectifiers were installed in the power conversion unit of the high-power lamps as well as the back reflector was coated providing more favorable spectral reflectance properties. The results of a single lamp/lens-combination show that the power on target in an aperture of 280mm in diameter was increased from 831W to 1446W while the peak flux was increased from 675kW/m² to 905kW/m².