Abstract <p>The study aims to investigate the impact of different operational parameters on the efficacy of a TiN nanofluid-charged heat pipe-assisted solar thermal collector under controlled indoor test conditions. The Taguchi method is employed for the optimization of operational parameters. A systematic experimental design was formulated considering key parameters such as TiN nanoparticle concentration, heat pipe evaporator diameter, collector tilt angle, filling ratio, and applied heat flux. The optimization process, performed using the L27 orthogonal array, identified the optimal parameter combination as a 50% filling ratio, 45° collector tilt angle, 12 mm heat pipe diameter, 0.1% TiN nanoparticle concentration, and 1000 W/m² heat flux, leading to a 27.8% enhancement in thermal efficiency compared to conventional working fluids. Experimental analysis was performed using Main Effect Plots and signal-to-noise (S/N) ratio. ANOVA confirmed that nanoparticle concentration and heat flux were the most significant factors affecting heat transfer performance, while collector tilt angle had the least impact. The integration of TiN nanofluid inside the heat pipe enhanced convective heat transfer because of localized surface plasmon resonance (LSPR) effects. Additionally, the optimized system achieved a solar energy efficiency of 78.5% and an exergy efficiency of 32.4%, demonstrating significant performance improvements. The developed regression models exhibited high predictive accuracy (<i>R</i>² &gt; 97%), confirming the reliability of the optimization framework. The research outcomes underscore the potential of TiN nanofluids in solar thermal applications, future research should focus on the long-term stability of TiN nanofluids, economic feasibility, and hybrid nanofluid formulations for large-scale implementation.</p>