Beyond Net Metering: Design and Performance of a Hybrid Solar Strategy for Cost Efficiency and Security of Supply in Intermittent Urban Grids

Distributed generation offers a critical pathway to sustainable urban energy; however, in-complete regulatory frameworks in emerging economies frequently force residential pho-tovoltaic (PV) systems into export-restricted operation. This study quantifies the empirical performance and opportunity costs of a demand-matched, zero-export PV system paired with an Internet of Things (IoT)-managed backup tier. A 54-month longitudinal sin-gle-case evaluation was conducted in Arequipa, Peru, utilizing a 1.36 kWp grid-tied array and a 0.6 kWh/day decoupled backup subsystem. Performance was rigorously bench-marked against a fully metered pre-PV counterfactual. The zero-export constraint man-dated a 96.3% self-consumption index (SCI), capping the self-sufficiency index (SSI) at 38.7% and yielding a utilization ratio (U) of only 24.1% against the site's technical poten-tial. Economically, the status quo produced a negative net present value (NPV) of −USD 885. However, scenario modeling demonstrated that activating a net-billing or net-metering framework robustly reversed the NPV to +USD 792 and +USD 4,587, respec-tively. Furthermore, the decoupled backup architecture successfully mitigated 97.7% of 43 recorded grid outages at a resilience cost of USD 3.2 per protected hour. The headline finding is therefore institutional, not technological: identical hardware shifts from val-ue-destroying to highly profitable purely through the regulatory mechanism governing surplus energy. We present two replicable sizing rules and propose the U metric to trans-late regulatory impasse into an internationally standardized reporting parameter, provid-ing an evidence-based roadmap for accelerating decentralized renewable energy in re-source-constrained grids (SDG 7, SDG 11).