The construction type of photovoltaic (PV) systems contains the fixed-type (FT), the single-axis tracking type (SASTT) and the dual-axis tracking type (DASTT) systems. The energy harvested by each type of PV systems are significant different. In addition to the effect of the types of PV systems, the tilt angle of a PV module that includes an FT system also affects the output power of the module. The assessment of energy harvested by different construction conditions of PV systems is an interesting topic in the PV industry and academia, but there is no comprehensive theory to support the quantitative numerical analysis of the assessment. In this study, a theoretical model of PV modules was first established to investigate the relationship between the performance of PV modules, and the solar incident angle and the electrical parameters. Furthermore, this model integrated with the solar trajectory on various construction types of PV systems. The long-term experimental results show that the proposed model can effectively and accurately evaluate the annual energy harvested by the PV systems. Finally, an improved PV system design was proposed, which can be applied to agricultural facilities for energy harvested assessment, such as greenhouses and screenhouses. The proposed method can also provide objective and quantitative information for agricultural authorities, owners of agricultural facilities, and PV system installers about the carbon reduction and additional economic benefits to achieve a win-win outcome for all parties.