Impact of inverter configuration on energy cost of grid-connected photovoltaic systems

This paper proposes a method to evaluate and optimize inverter configurations for grid-connected PV systems. It is studied by Monte-Carlo analysis that how the inverter configuration and its operation strategy would impact on lifetime energy yield and the levelized cost of energy (LCOE) considering the PV array scale, environmental conditions, system cost, inverter efficiency and reliability. The efficiency characteristic of parallel inverters with a common DC bus is deliberated along with the optimal operation strategy. Inverter system performance ratio (ISPR) is proposed as an overall index of lifetime energy conversion efficiency. A case study is performed to demonstrate the proposed method. It shows that the configuration with a common DC bus is a potential solution to reduce the energy cost of PV power generation systems. As ancillary results, it is found that optimizing the PV panel orientation can improve the probability distribution of solar irradiance on the panel, and it is confirmed that an oversized PV array may help reduce the energy cost.

► Minimizing the energy cost is our final objective when designing PV systems.
► It is studied how inverter configurations impact on energy yield and energy cost.
► Environmental conditions, inverter system efficiency and reliability are considered.
► The configuration with a common DC bus has potential to lower the energy cost.
► The system efficiency and cost should be compromised from the system point of view.