Phase-change　thermal　storage　technologies　are　becoming　increasingly　indispensable　in　the　field　of　renewable　energy,　and　researchers　have　been　striving　to　achieve　high　thermal　storage　performance　in　storage　devices.　To　enhance　the　application　potential　of　phase-change　thermal　storage　units　based　on　micro　heat　pipe　arrays,　theoretical　analysis　is　applied　to　optimize　the　operating　parameters　and　the　fin　structure,　addressing　the　research　gap　caused　by　insufficient　theoretical　analysis.　Therefore,　an　accurate　thermal　resistance　network　model　is　developed,　and　machine　learning　algorithms　are　employed　for　the　multi-objective　optimization　of　the　fin　structure.　The　optimal　heights,　widths,　and　thicknesses　in　two　directions　of　the　fins　are　42.2,　3.7,　0.3,　and　0.8　mm,　respectively,　resulting　in　a　15.8　%　increase　in　charging　power　compared　to　the　initial　structure　without　increasing　metal　consumption.　Additionally,　it　is　recommended　that　the　design　flow　rate　be　increased　by　26　kg/h　for　each　additional　thermal　storage　unit　connected　in　series.　Finally,　a　phase-change　thermal　storage　device　is　designed　for　a　solar　water　heating　system,　and　its　applicability　is　simulated　and　analyzed.　This　study　provides　design　guidance　for　this　novel　thermal　storage　device　and　promotes　its　application　in　the　field　of　renewable　energy.　©　2024　Elsevier　Ltd