Building-integrated solar thermal system is a new tendency in the building sector. An active solar wall is studied in this paper, which integrates flat plate solar thermal collector and building wall. The performance of an active solar wall is predicted by the state space model and measured by experimental testing respectively. The calculated results by state space model agree well with the measured data from experimental testing, which indicates that state space model is valid. Thermal analysis for a particular solar wall is conducted in clear and cloudy days either in summer or winter respectively by state space model under Shanghai meteorological conditions and compared with the separate wall. The results indicate that: (1) Integration has a little effect on the useful heat gains by solar collector. In clear summer days, the useful heat gains are less than the separate solar collector by about 2-3%; In clear winter days, the useful heat gain is greater than the separate solar collector by about 5-8%; (2) Integration has great effect on the heat flow through walls. In clear summer, heat flow into the room through solar wall is significantly reduced by 55-63% than the separate wall. It is favorable to reduce cooling load. In winter, heat loss through solar wall is heavily reduced by about 80-88% than the separate wall. It is favorable to reduce the space heating load in winter. (C) 2016 Elsevier Ltd. All rights reserved.