Photovoltaic is a clean and renewable energy. Irradiation and performance of PV system are important to PV benefit. Different estimative models of irradiation had been proposed. Some of the models are complicated in calculation with locality, and the strategy of PV application affects the performance of system. The purpose of the work is to build a simplify method, by means of the equations of slope irradiation ratios, for easily evaluating the PV power transformed by modules on building envelope. Developing an evaluation model of strategy for PV application on building can find the applicable space and equipment and suitable use type. Simultaneously, the local irradiation and PV operation were recorded. The results of validation of the estimated equation were presented by correlation analysis. The equations and estimation can be a reference for evaluating PV application in building. A PV interior lighting integrated with grid lighting system were achieved and proposed as suitable use type of BiPV. The evaluative model of PV applicability and the suitable use type can be a strategy of BIPV technology applied in building design.