In　this　paper,　the　performance　of　a　polycrystalline　silicon　photovoltaic　module　and　photovoltaic/thermal　module　are　experimentally　investigated　under　outdoor　conditions,　using　a　roll-bond　thermal　collector　attached　on　the　backside　of　the　photovoltaic　module.　Furthermore,　the　temperature,　pressure　and　velocity　distributions　across　the　photovoltaic/thermal　module　are　simulated　using　a　steady　state　thermal　model.　Compared　with　the　photovoltaic　module,　the　performances　of　photovoltaic/thermal　module　with　and　without　the　coolant　circulation　are　both　examined　using　a　water　volume　of　100　L　and　a　coolant　mass　flow　rate　of　0.034　kg/s.　Using　a　design　with　a　timed　supplement　water　strategy,　the　electrical　energy　produced　by　the　photovoltaic/thermal　system　has　been　increased　by　3.25%.　Compared　without　supplement　before,　the　electrical　energy　can　be　extra　increased　more　than　1%.　A　good　agreement　is　found　between　simulated　and　experimental　results.　There　is　no　doubt　that　the　output　performance　of　the　photovoltaic/thermal　system　can　be　improved　effectively　by　the　design　of　timed　supplement　water.　(C)　2019　Elsevier　Ltd.　All　rights　reserved.