Comparing Central Inverters and String Inverters in Utility-Scale Solar Systems in North America

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No decision has more impact on the system cost and performance than the choice of inverters as this dictates design constraints for much of the balance of system. Today, system designers have more options than ever when architecting solar systems. While this may seem like a great advantage, these options necessitate an ever-growing number of decision points in the design process.

Before selecting brand or model the designer must first choose the macro level class of inverters, central or three phase string inverters. Until recently, the normalized price of string inverters (as measured in $/W) was much higher than central inverters, making the decision to use central inverters for utility-scale quite straightforward. That unit price gap has greatly diminished, resulting in a heightened debate on the relative merits of central and string inverters, often without empirical data to support the arguments.

The jury is still out on which is the so-called “best solution” and likely for good reason as the overall system size has such a significant impact on the relevant answer. In my article for Renewable Energy World, I analyzed the relative merits of central and string inverters in a typical system in North America.

The analysis is limited to the relative costs of central and string inverters for utility-scale projects in North America in three areas: CAPEX, inverter service life and true cost of service.

Read article on or view in-depth version with further analysis of utility-scale system performance requirements and operating efficiency here.

About the Author: Evan Vogel joined Schneider Electric in 2016 as Director of Marketing for Solar and Energy Storage, where he manages strategy and marketing for global energy storage and solar lines of business. Evan is a 30-year veteran of the power conversion and energy industries. He is a past officer of the Power Sources Manufacturers Association (PSMA) and former head of the PSMA Marketing Committee. Evan holds a BSEE from NYU, and a dual MBA in Marketing and Finance from Adelphi University.