Brewer’s spent grain (BSG) is the residue left after separation of the wort during the brewing process and is available in large quantities throughout the year.A large amount of agro-industrial waste is produced annually around the world from the beneficiated agricultural products or in food industrialization. In Ethiopia the main current application of this waste is in the area of animal feed, in contrast to this there is a shortage of renewable energy in this country. This thesis presents about the solid waste in brewing industry, which is the brewer spent grain/ malt bagasse describing its thermal properties such as moisture content and chemical composition, means of converting it to bio-gas, thermal properties of biogas, design and construction of solar assisted upper ground digester system, amount of bio-gas produced and the potential application in small scale house hold sector, especially rural areas. When BSG is anaerobically digested, it produces high amount of biogas. This biogas production requires some biological and thermal processes. Based on these applications to use this biomass energy source design of the constituent parts, simulation of biogas producing plant and experimental test as well as its viability are the main parts.According to various literatures the brewery spent grain can generate 0.3-0.5 m3 of biogas per kg of volatile solid. But in this work the temperature it takes for fermentation starting from the first day in which the slurry is added to the digester upto the end of digestion the various data are recorded. The total number of days for this is 25-30 with various temperature readings at different parts. The maximum average temperature recorded during these days for digester are 38.3oC,39.1oC and 39.5oC at bottom, east side and west sides respectively.These values are recorded only at the outside of digester tank, but the slurry temperature is taken as the maximum value of the environmental temperature. The environmental temperature is average of all days’ record which is 32.5oC. This experiment is conducted for sample test using 19kg of brewery spent grain. But theoretical analysis of this experiment study is analyzed with 11.8125m3 volume of digester and can give a result three times greater than that of this sample test.