This paper presents the design, development and results obtained with a mobile laboratory: the PV Mobile Lab. With the development of this powerful tool, Enertis Solar is the first IEC 17025 accredited laboratory capable of performing on-site test in PV modules. The PV Mobile Lab is designed to perform the following tests: visual inspection, Peak Power determination in STC, electrical insulation, IR Thermography and electroluminescence imaging. The design of the mobile laboratory ensures the reliability of the results as if conducted in a conventional laboratory. Its innovative design based on an expandable system has allowed us to implement a solar simulator of tunnel type (illuminated area 2x2 m2 and lamp -DUT distance 5.5 m) in a vehicle that weights less than 3,500 kg. The spectral, temporal and spatial (non-uniformity) stability of the simulator remain within the parameters that define it as a class A(+)A(+)A(+) simulator. The environmental conditions during the performance of the tests are controlled and the flash incidence is normal to the module surface. Furthermore, due to the implementation of programmable switches, test sequences have been fully automated optimizing the time required for characterizing a module. The paper also presents the results obtained in the quality control of 500 modules tested during the commissioning test of 2 PV plants located in the UK. (C) 2014 The Authors. Published by Elsevier Ltd.