The performance prediction of Solar Integrated Collector-Storage system(ICS) is determined in terms of three generalised non-dimensional grouped parameters using transient one-dimensional analysis. These nondimensional parameters are primarily a combination of physical characteristics representing thermal performance curves for solar ICS system. The inter-relation between these are summarised by a nomogram which helps in predicting the system performance graphically for a particular locality, or may deduced from it by simple calculations. This method does not require detailed knowledge of system parameters for predicting system performance. These dimensionless groups include information available readily to a designer pertaining to dimensions, thermal characteristics and operating conditions. The present study is based on the analysis carried out by Hobson and Norton for thermosyphon solar water heater.