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The value of repowering legacy solar inverters

Published in: Solar, Talking Point, Exclusive Articles

The value of repowering legacy solar inverters image

Owners of aging solar plants should evaluate inverter replacement before repeated failures force the decision. A low repair invoice can obscure a much larger cost: the electricity a plant cannot sell while equipment is out of service. For projects with valuable legacy power purchase agreements, planned repowering deserves a place in the asset management budget alongside routine maintenance.

Solar projects built between 2009 and 2016, including those operating under 25-year power purchase agreements (PPAs), may still have substantial earning potential. Preserving that value depends on keeping the equipment available. Expired warranties, scarce replacement components, rising parts costs and fewer technicians familiar with older platforms make that task increasingly difficult.

Repair remains a reasonable response to an isolated failure when parts and qualified labor are available. The problem emerges when each repair returns an obsolete inverter to service without addressing the conditions that caused repeated outages. Portions of a site can remain offline for months, or longer, while owners search for a workable solution.

The economics begin with the revenue at risk. The accompanying baseline chart models a 1 MWac block with single-axis trackers and a DC-to-AC ratio of 1.3, using a PPA rate of $0.01 per kWh. It compares four locations to show how regional production affects earnings. Values can be adjusted by the ratio of the actual PPA rate to this baseline rate.

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