As well know that UMG Si gives a good opportunity to make cheaper ingot,wafer,cell and consequently reduce the cost.So in order to make clear the possibilities and potential risks of UMG mass production,some studies based on casting ingot to multi cell level were done with standard cell process.The results show from bottom to top orientation of casting multi bricks,resistivity ranged from 1.0 to 1.5 and became higher and higher.The bulk lifetime was 40 us lower than normal multi wafers.And [Fe] concentration was also higher than normal multi wafers.Even after diffusion which can remove the irons with gettering,wafer bulk lifetime was still ~20us lower than diffused normal multi wafers.This decided that the final UMG cell performance was also ~0.3% abs.lower than normal multi wafers.Look deeply into the I-V data,UMG wafers show higher Uoc/Irev but lower Isc than normal multi cells because of high compensation.Going further,UMG multi wafers/cells show similar LID with normal multi wafers.However,reverse EL show that UMG multi cells will show lower breakdown gate voltage than normal multi wafers.This makes UMG multi wafers/cells risky into mass production with current main standard module design.Generally speaking,considering lower efficiency,breakdown gate voltage and currently low normal multi wafer cost,UMG multi ingots and wafers become not so attractive now.