The focus of this project is to develop a PV monitoring system that requires the development of mathematical model to estimate the solar insolation based on PV output power. The sustainability and reliability of PV based electricity generating system depends on the solar insolation, and optimization is important to meet the demand of the load. It is important to measure solar insolation in order to obtain an optimum PV sizing and also the system must be attached to a monitoring unit. The monitoring unit will be able to give feedback, so that the performance of the system is kept at optimum level. The relationship between solar insolation and output voltage of PV module was determined by using suitable experimental set up, and the modeling equation was used to determine the level of solar insolation. Monitoring software was developed using Visualbasic.Net together with hardware package, which can transfer the voltage signal from the PV panel to the computer. The integrated system can be used by multiple users to remotely monitor the performance of the PV system via internet. © 2011 IEEE.