This　letter　suggests　a　dc-dc　converter　with　ultra-high　voltage　gain　based　on　Y-source　magnetically　coupled　network　for　interfacing　renewable　resources　application.　Utilizing　the　characteristic　of　Y-source　network,　the　converter　can　achieve　flexible　adjustment　of　voltage　gain　and　high　voltage　conversion　ratio　at　small　turns　ratio　of　coupled　inductor.　On　the　basis　of　Y-source　network,　it　also　features　continuous　input　current,　lower　voltage　stress　of　switch　and　output　diode,　and　wider　control　range　of　duty　cycle.　At　the　output　side,　a　pumping　capacitor　cell　enhances　boosting　capability　with　effect.　The　theoretical　operation　principle　of　the　converter　is　analyzed　thoroughly,　including　the　case　of　considering　the　influence　of　leakage　inductor.　Moreover,　the　performance　analysis　is　presented　in　detailed.　A　200-W　experimental　prototype　was　constructed　and　the　validity　of　proposed　converter　was　verified.　©　1982-2012　IEEE.