Design and Evaluation of Hybrid Energy Systems in a Campus-Scale Application

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HELVACI H. U., KEÇECİ A.

Gazi University Journal of Science Part A: Engineering and Innovation, vol.13, no.1, pp.306-333, 2026 (TRDizin)

Abstract

This study presents a scenario-based techno-economic evaluation framework for grid-connected institutional hybrid energy systems aiming to reduce grid dependency through renewable energy integration. The framework is demonstrated through a campus-scale application at Doğuş University Dudullu Campus, where electricity demand is currently met entirely by the national grid, resulting in high energy costs and carbon emissions associated with fossil fuel-based generation. In the study, four different scenarios were modelled using HOMER Pro software: (1) grid-supported photovoltaic (PV) and converter systems; (2) systems where renewable energy contribution is increased with battery integration; (3) systems consisting of PV, wind, and batteries based entirely on renewable energy sources; and (4) Policy-Aware Carbon-Integrated Transition (PACIT), which evaluates the optimal configuration under regulatory frameworks including monthly net metering and a $40/tCO₂ carbon tax threshold. Across all evaluated scenarios, the grid-connected hybrid system with battery integration (Scenario 2) consistently emerged as the most techno-economically favorable option. In this scenario, the initial investment cost was calculated as $991,426, the levelized cost of energy (COE) was $0.0817/kWh, and the annual operating cost was $149,810. In addition, the renewable energy rate reached 50.3%, and carbon emissions were reduced by 45.96%. Scenario 3, which is based entirely on renewable energy, provides zero carbon emissions but is not economically viable due to the $12.1 million investment cost and high energy costs. The results indicate that grid-connected hybrid energy systems offer the best balance in terms of cost and sustainability. By offering a transferable evaluation model, this study provides actionable insights for institutional energy planning and policy development in comparable grid-connected facilities.