Using　renewable　energy,　especially　solar　energy,　is　an　essential　requisite　for　preventing　global　warming　and　climate　change.　Solar-powered　steam　generation　is　one　of　the　recent　solutions　to　the　problem　of　environmental　pollution　and　can　be　a　promising　way　to　generate　clean　energy.　In　this　study,　the　superficial　and　volumetric　approaches　of　the　zinc　oxide　nanoparticles　(ZnO)　in　solar　vapor　generation　have　been　compared　experimentally.　For　the　volumetric　approach,　the　nanofluid　performance　at　different　mass　concentrations　(0.001%,　0.002%,　and　0.004%)　on　the　solar　vapor　generation　was　examined.　For　the　superficial　approach,　the　evaporative　performance　of　delignified　mulberry　wood　coated　by　ZnO　nanoparticles　as　an　absorbent　(ZnO-Wood)　was　investigated.　Moreover,　the　effect　of　nanoparticle　size　on　optical　and　evaporative　properties　was　evaluated.　Finally,　the　economic　performance　of　the　ZnO　nanofluid　was　compared　to　the　other　nanofluids.　The　results　indicated　that　the　evaporative　efficiency　of　the　nanofluids　containing　ZnO(50　nm)　nanoparticles　at　3　suns　(3　kW/m2)　was　approximately　two　times　greater　than　that　of　water　(18%).　However,　the　evaporative　efficiency　of　ZnO-Wood　was　3.15　(56%)　times　greater　than　that　of　water.　In　addition,　the　results　of　the　nanoparticle　size　effect　showed　that　increasing　the　size　of　nanoparticles　from　20　nm　to　50　nm　in　the　superficial　and　volumetric　approaches　increases　the　evaporative　efficiency　by　roughly　10%　and　3%,　respectively.　Finally,　the　cost　analysis　of　nanofluid　for　solar　vapor　generation　illustrated　that　ZnO　nanoparticles　are　cost-effective　compared　to　other　nanoparticles　presented　in　the　literature.　©　2020