Optimizing a large-scale solar power project on uneven terrain using terrain-following technology

Solar expansion in the Philippines is constrained by competition for flat agricultural land and the cost of site preparation on steep terrain. This paper evaluates whether terrain-following photovoltaic design can improve the feasibility of a 50 MW-class solar development in Bacnotan, La Union. An integrated method combining LiDAR-based terrain modeling in Surfer, PVsyst energy simulation, scenario-based financial analysis, and review of Philippine policy and permitting requirements was applied to compare progressively optimized land-development options. Results show that strategic terrain modification increased usable area from 33% to 55%, expanded nominal DC capacity from 30.93 to 51.53 MWp, and raised P50 annual energy output from 42.06 to 70.08 GWh. The optimum scenario required about 338,090 m³ of land development and improved project IRR from 8.08% to 9.65% and equity IRR from 8.82% to 12.13%. Terrain-following design also reduced grading dependence, improved land retention, and supported erosion and drainage management. The paper concludes with an engineering management framework linking site assessment, design optimization, financial screening, regulatory alignment, and operational monitoring for solar projects on uneven land.