To　apply　phase-change　thermal　storage　in　heat-pump　systems,　a　low　heat-transfer　temperature　difference　is　required.　The　typical　temperature　material　requirements　for　phase　change　limit　the　application　of　its　thermal　storage　in　heat　pump　energy　supply　systems.　This　study　introduces　a　novel　phase-change　thermal　storage　device　suitable　for　a　renewable　energy　supply　system　composed　of　multichannel　flat　tubes　and　closed　rectangular　fins.　Performance　experiments　and　optimisation　of　the　connection　geometry　of　the　thermal　storage　units　under　low　heat-transfer　temperature　differences　were　carried　out.　When　the　inlet　temperature　of　the　heat　transfer　fluid　was　55　degrees　C　(the　melting　point　of　the　phase　change　material　is　50　degrees　C),　the　energy　storage　density　and　gravimetric　specific　power　can　reach　175.16　kJ/kg　and　27.93　W/kg　respectively,　which　has　obvious　advantages　compared　to　relevant　devices　in　the　literature.　A　dimensionless　energy-efficiency　ratio　was　used　to　optimise　the　device.　It　was　shown　that　the　series　type　can　significantly　increase　pressure　loss　while　improving　heat　storage　performance,　and　optimising　the　structure　and　operation　design　parameters　of　parallel　components　is　more　beneficial　in　terms　of　device　performance　improvement.　The　optimal　operating　flow　corresponding　to　different　heights　of　the　novel　thermal　storage　unit　in　parallel　was　provided,　thus　laying　a　theoretical　foundation　for　practical　applications.