Abstract:
Sri Lanka’s recent energy policies are focused on promoting economically viable solar
power generating schemes introducing novel market segments. It’s envisioned to
ensure nation’s energy security while promoting utilization of indigenous energy
generating resources. Recent 1 MWp solar power development scheme is one such
novel market segment. PV inverters play a significant role in any PV plant
performance. Lack of research on identifying the technically and economically most
suited PV inverter architecture has caused high risk of failed project objectives.
Following research presents a comprehensive framework for a techno-economic
comparison of different PV inverter architectures which are central inverters, string
inverters, micro inverters and power optimizer systems. 1 MWp capacity PV plant
models are designed for analytical purposes of the research. Technical aspects such as
energy yield, safety aspects, power output quality, reliability and performance
monitoring are assessed using simulation tools (PVSyst, PSCAD and MATLAB), field
data analysis, Cost Priority Number method and Markov reliability models. Economic
impact is evaluated using Levelized Cost of Electricity calculations and project
financial assessments followed by a sensitivity analysis. It’s found that distributed
power electronics in PV systems provide higher energy yield, reduced safety risk,
higher reliability and lower system down-time due to failures compared to central and
string inverters. String inverters and power optimizer systems are more economically
feasible in 1 MWp scale. Finally, it’s concluded that the presented methodology
furnishes a proper techno-economic comparison for different PV inverter
architectures.
