Comparing Power System Architectures for Domestic Lighting in Isolated Rural Villages with HOMER

Abstract

Selecting power system architectures for rural electrification is a process dependent on several technical, economic, and human resource design requirements. PV-generator-battery systems are common for large village loads while PV-battery systems tend to be preferred for smaller village loads. This study compares three power system architectures (PV-battery, PV-generator-battery, generator only) for part-time evening domestic lighting in a small isolated rural village. Although the evening load profile disfavors PV systems, the small load also disfavors generators. Multiple technical and financial figures of merit are used to compare systems. Detailed consideration is given to the relationship between power availability and power cost, a metric uncommon to rural electrification studies. The net present cost of the generator only system and hybrid system is invariant with changes in annual unmet load allowance. The net present cost of the PV-battery system decreases with increases in unmet load-the higher granularity in the installed capacity of PV-battery systems allows reductions in system cost if project stakeholders allow power shortages for evening lighting. This design consideration can reduce the high initial of PV-battery systems. For the domestic lighting load modeled in the study the PV-battery architecture becomes the lowest cost option for an unmet load allowance of 1% or greater.