The　growing　interest　in　extensive　distribution　generating　unit　(DG)　integration　into　the　grid　creates　new　challenges　for　power　system　planners　and　operators.　The　non-optimal　placement　of　renewable　energy　sources-based　(RES)　DG　units　in　distribution　networks　impacts　grids＇　reliability　and　stability.　This　paper　proposes　a　K-means　clustering　technique　for　the　optimal　placement　of　multiple　photovoltaic　distributed　generation　(PVDG)　units　using　voltage　stability　index　(VSI),　the　voltage　risk　index　(VRI),　and　the　hosting　capacity　under　different　PVDG　local　voltage　control　techniques.　The　proposed　technique　was　tested　on　the　IEEE　33-bus　radial　distribution　network.　After　the　optimal　placement　of　the　PVDG　units,　the　VSI　and　VRI　for　the　base　network　were　improved　32.76%　and　90.1%,　respectively　by　the　best　simulation　case.　The　voltage　profile　was　improved　by　3.6%　and　the　total　active　power　loss　was　reduced　by　67.7%.　The　results　show　that　the　proposed　technique　is　effective　to　allocate　multiple　PVDG　units　for　distribution　network　planning　and　expansion　as　well　for　increasing　the　PVDG　penetration　while　minimizing　the　voltage　stability　and　risk　indices.　©　2022　IEEE.