ByJohn R. Balfour BS, MEP, PhD, President and CTO of High Performance PV

In addressing PV plant repowering for the upcoming 2018 Solar Asset Management Conference, we will discuss PV repowering in two sessions. The panels will be look beyond simply refurbishing, repairing, restoring or renovating the power plant. The focus is on delivering improved lifecycle performance, cost and risk reduction while extending a profitable plant’s economic life.

The simple fact is that repowering is a requirement and reality of a more mature industry.  

PV System repowering in its most effective modes are the application of a specific set of process and procedures that address the realities of the condition and health of the PV system throughout its operational lifecycle. This goes well beyond a simple O&M cycle improvement.

It appears there are two distinct forms of repowering:


The first is a process that begins at plant concept with a repowering plan which addresses the long term factors of what will deliver the most consistent performance, output and revenue throughout a plant’s life. It is intended to address the Levelized Cost of Energy (LCOE) with improved accuracy while keeping in mind that a longer life cycle reduces the cost of energy while improving the profitability of the project.

This process tends to dramatically reduce, mitigate or eliminate many of the shortcomings that artificially raise the cost of O&M and/or reduce the viability of the project throughout its life.

This form of repowering is common in the utility industry for power generating plants, along with marine, aerospace and a number of other established mature technology groups. Their focus is long-term dependability while specifically avoiding the short-term profit trap with least cost corner cutting.


The second tends to focus on distressed and acquired assets that did not begin with a repowering plan.

These assets may have been purchased while still meeting their performance requirements or they may be acquired as the plant begins to fail meeting those requirements. As a result the goal is to avoid bankruptcy, default and the re-rating of the plant and it’s PPA.

This article deals specifically with the first variety of powering.

Repowering is not just the process of replacing older plants or components with newer ones focusing on improved nameplate capacity or efficiency with a net increase of power generated.

Repowering is an operational business strategy where asset values are maintained or improved. This is achieved by addressing the underlying reliability, availability, maintainability and safety (RAMS) of a plant. It gauges the tangible duty cycle of plant components for its physical environment, usage and purpose by providing a functional plan and timetable to maintain the plant’s ability to meet its contractual requirements and do so in a cost effect manner for an extended period of time.

What is a repowering plan?

A repowering plan:

  • Defines the potential viable lifecycle of the plant

  • Provides detailed consideration of the fact that the entitlements, property, environmental engineering, and utility infrastructure are in place and are paid for

  • Addresses specification prior to the typical EPC process giving owners control of what is built

  • It addresses 200 groups of limiting factors where potential plant weaknesses are identified and defined at specification, then addressed in detail during the system delivery process

  • Results in a bid package where all EPC bidders are bidding on the same system for accurate comparison. This saves EPCs a substantial amount of marketing and pre-engineering time and cost while reducing the risk following benchmarking and commissioning.

  • It gives owners what the want by providing specifications that meet expectations

What does the resulting system look like?

A number of the infrastructure costs have already been fixed and paid for with minimal modification or and lower O&M costs. As a result, the repowering plan no longer focuses on 20 to 25 years, it focuses on a project life of 50 years or more.

How is this possible?

Fact: Modules, inverters and most of the BOS will not operate or last for five decades!!!

Nevertheless, the entitlements, property, environmental engineering, and utility infrastructure are designed for longer life already, with minor cost differentiation. The costs in building a better more robust plant result in: improved O&M savings, more consistent operation and output while providing the ability to amortize cost and risk over a longer period. This is a more effective business approach and far more financially satisfying to investors, owners and offtakers.

As a result it makes no sense to deconstruct the project at the end of 25 years practically starting from scratch. Effective repowering plans maximize and/or respond to the following:

  • Site and Environment:
    More attention is paid to the actual site and environment which results in better selection of materials and components

  • Specification:
    By focusing on the details of a comprehensive specification first, better component selection and design results in far fewer issues driving up O&M.  As a result, actual long term predictability is effectively improved.

  • Financials:
    Project financials are enhanced giving more attention to the quality and long term viability of the EOM organizations that are manufacturing modules, inverters and other components. This requires a better understanding of OEM ability to provide products and warranty services beyond the first year or two of operation thereby reducing the number of issues that default to the O&M budget. Every issue that is avoided, mitigated or reduced improves the system balance sheet.

  • Product Changes:

    • The planning process focuses heavily on the reality that modules will change in voltage, current and form factor, which impacts how the inverter is fed.

    • It addresses the fact that future inverters may also vary substantially from today and provides consideration to space, reconfiguration requirements and the ability to meet the future needs of the plant.

    • The process gives consideration to potential later addition to energy storage and other issues that may change the physical plant design, providing greater future flexibility.

How repowering is discussed, considered and applied will take time and effort. The greater the success in addressing effective repowering means the greater business and financial success for the stakeholders involved. This is a substantive increase in asset value while reducing time and the consequences of lost time or project disruptions. The opportunity to realize repowering is obtainable today with the capability of showing results in a matter of a few years.

In a following article, we will address the issues of repowering for distressed and acquired assets, thereby relying on experienced industry knowledge to address and bypass major planning, technical and financial pitfalls.

For additional information or questions please feel free to contact John R Balfour at: