This study focused on the development of an indirect forced solar dryer that incorporates a three-sided flat plate solar collector (TSFPSC) specifically designed for increasing thermal efficiency, and the system used for drying salted tilapia fish fillets (STFF). The investigation analyzed three fillet thicknesses 4 mm, 8 mm, and 12 mm, employing both open sun drying (OSD) and the developed solar dryer (DSD), with a constant airspeed of 0.5 m/s. The research additionally developed thin-layer drying models (TLDM), assessed drying parameters, and performed an extensive techno-enviro-economic analysis. Results showed that the initial and final moisture content (MC) (w.b. %) of the STFF were 74.83 and 18.84%, respectively, and reached the equilibrium MC after 16–20.5 h for the DSD and 30–36 h for the OSD, which means the drying time reduced by about 53.3%, and 61.11% compared with the OSD. This reduction in drying time demonstrates the effectiveness of the developed solar dryer. The effective moisture diffusivity (EMD) of different STFF samples at both drying systems was 0.51 × 10–10 to 9.16 × 10–10 m2/s. In addition, all eleven basic TLDM were applied to predict the drying behavior of STFF during the drying process, while the combined Two-Term and Page model had the best fitting for the OSD system, and the modified Midilli II model and combined Two-Term and Page model had the best fitting for the DSD system. In terms of economic analysis, the annual capital and investment costs were calculated to be $22.458 and $21.334, respectively. Additionally, the environmental analysis indicated an energy payback (EP) period of 1.59 years, with a net CO2 mitigation of 14 tons realized over the operational lifetime of the DSD.