RESOLV Intelligence / O&M

14 May 2026 / 6 min read

Solar plant underperformance: what a first plant review should establish

Before anyone quotes a repair, the plant has to be measured against what it should have produced.

An owner who suspects their array is underperforming usually receives two kinds of proposal: a cleaning contract or a replacement quotation. Neither is an engineering answer. The first step is to establish a baseline.

The five things a review should produce

• /A modelled expectation for the array as designed, using the site's own weather record over the review period.
• /Actual generation from the monitoring platform or the inverter logs, at daily resolution.
• /The gap between the two, expressed as a percentage and attributed to identifiable causes.
• /A physical inspection covering soiling, shading, hotspots, string configuration and water ingress at connectors.
• /A prioritised list of interventions with the expected recovery for each, so spending can be sequenced.

The causes that are usually found

Soiling in an industrial or agricultural environment, shading that appeared after a neighbour built something, a string that dropped out after a fuse failure, an inverter running in a derated mode because of a thermal issue, and monitoring that stopped reporting months ago and nobody noticed. Most underperformance in mature plants is a combination of the ordinary and the ignored.

What the review is not

It is not a warranty claim, though it may produce the evidence for one. It is not a cleaning proposal. It is a documented statement of what the asset should be producing, what it is producing, and why the difference exists. From that document, an owner can decide whether to maintain, repair or replace, with a defensible basis.