As　an　effective　carrier　for　integrating　distributed　photovoltaic　(PV)　power,　building　microgrid　is　an　effective　way　to　realize　the　utilization　of　distributed　PV　local　consumption.　To　ensure　the　sustainable　development　of　building　microgrids,　an　economic　analysis　model　of　building　microgrids　is　established,　which　takes　into　account　the　construction　costs　of　microgrids　as　well　as　the　operational　benefits.　The　benefits　of　microgrid　operation　mainly　include　explicit　and　implicit　benefits,　while　an　economic　assessment　index　is　established　based　on　economic　benefits.　The　overall　economics　of　microgrids　are　evaluated　by　calculating　the　revenues　generated　during　the　investment,　construction,　and　operation　phases　of　building　microgrids　to　make　rational　response　decisions.　To　this　end,　as　an　example,　a　detailed　analysis　is　conducted　to　evaluate　the　economics　of　building　microgrid　in　Fujian,　China.　The　results　of　the　study　provide　a　reference　basis　for　evaluating　the　economics　of　building　microgrid　operations　and　establishing　a　guarantee　mechanism　for　sustainable　development.　©　2024　IEEE.