This　paper　presents　an　algorithm　for　estimating　three　components　of　total　solar　irradiance　on　vertical　surfaces　in　coastlands,　including　direct,　sky　diffuse　and　ground　reflection　irradiance.　The　algorithm　aims　to　cover　changeable　weather　and　ground　surfaces　in　coastlands.　For　this　purpose,　Sanya　located　on　Hainan　Island　of　China　has　been　selected　as　a　representative　city.　Initially,　a　dataset　of　horizontal　irradiance　measured　from　2005　to　2014　has　been　used　to　statistically　analyze　the　frequency　distribution　of　sky　conditions,　resulting　in　a　classification　of　coastal　weather　into　4　categories.　Afterward,　using　the　vertical　irradiance　data　collected　by　a　novel　measurement　system,　the　performance　of　15　sky　diffuse　irradiance　models　has　been　compared　under　coastal　weather　types.　As　a　result,　an　algorithm　for　vertical　sky　diffuse　irradiance　adapted　to　all-sky　conditions　(Alg-s)　is　developed.　Concurrently,　regression　models　of　reflection　irradiance　from　sea　and　beach　on　vertical　surfaces　(Mr)　are　established　using　correlation　analysis　and　the　least　squares　method.　Combining　the　above　two　sub-models,　an　allsky　conditions　total　solar　irradiance　model　on　vertical　surfaces　in　coastlands　is　developed.　Compared　to　previous　studies,　the　new　model　improves　the　prediction　accuracy　of　total　vertical　irradiance,　with　RRMSE　and　MAPE　reduced　by　14.2　%　and　10.6　%　respectively.