Maintenance, energy audits and power quality

Maintenance

Solar systems have few moving parts, which is often mistaken for needing no attention. In practice output is lost to soiling, shading that develops as vegetation grows, connections that degrade, and failures in a single string that reduce output without stopping the system.

A maintenance visit covers array condition and cleaning, inverter status and logged faults, protection devices, thermal inspection of terminations, and a comparison of actual generation against what the system should produce for that season.

Energy audits

An audit establishes where energy is actually going, using measurement rather than assumption. It is the honest first step before any recommendation to spend money on generation: sometimes the cheapest kilowatt-hour is the one that was being wasted.

A maintenance visit, item by item

• Array condition. Soiling, physical damage, hot spots, delamination, and anything growing into the array’s line of sight since the last visit.
• Cleaning, where soiling justifies it — with water and appropriate method, not abrasives or detergents that damage the surface.
• Mounting structure. Fixings, corrosion, movement, and the condition of roof penetrations and their seals.
• Cable management. DC cable that has slipped into standing water or is resting on a roof surface, UV damage, and strain on connectors.
• Connections and terminations, checked thermally under load, which finds the ones that are degrading before they fail.
• Inverter. Status, logged faults and warnings, ventilation, filters, and whether its settings still match the design.
• Protection devices. Isolation, surge protection status, and correct operation of earth-leakage protection.
• Earthing. Continuity of array bonding and the condition of the earthing arrangement.
• Batteries, where fitted: state of health, cell or module balance, ventilation and temperature.
• Generation review. Actual output against expected output for that season, which is the check that gives all the others context.

How often is enough

There is no universal interval, and anyone quoting one has not seen the site. What decides it:

• Dust. A site near unpaved roads, fields or construction soils far faster than a suburban roof, and the dust season matters more than the calendar.
• Industrial exposure. Cement, fertiliser and process exhausts leave deposits that ordinary rain does not clear.
• Trees and neighbouring construction, both of which introduce shading that did not exist at commissioning.
• System size and criticality. A site that loses money when the system is down warrants more attention than one that does not.

For most rooftop systems a scheduled inspection with cleaning as needed, plus an electrical inspection at a longer interval, is a reasonable starting point — refined once we have seen how the site actually behaves.

What to watch yourself, monthly

You do not need instruments to catch most problems early:

• Compare generation with the same month last year, not with last month. Seasons move too much for month-to-month comparison to mean anything.
• Look for a step change. Gradual decline is usually soiling. A sudden drop is a fault — a string offline, a tripped protective device, an inverter derating.
• Check the inverter for warnings, not just for a green light.
• Notice the evening, if you have batteries: a bank that used to carry the load until 11 p.m. and now stops at 9 p.m. is telling you something.

Anything that reads as a step change is worth a call rather than a wait.

Diagnosing underperformance

When output is below expectation, the sequence is measurement, not replacement:

1. Confirm the expectation. Compare against what the system should produce for that irradiance and season, allowing for temperature — not against the number on the invoice.
2. Isolate by string. Comparing string currents finds a failed or shaded string quickly.
3. Test insulation resistance on the DC side, which finds moisture ingress and damaged cable.
4. Thermally inspect modules, connectors, isolators and terminations under load.
5. Read the inverter’s history, which usually records the fault that the site noticed as “lower bills stopped”.
6. Re-check shading against what was measured at survey. Vegetation and neighbouring buildings both grow.

Taking over someone else’s system

We take on systems installed by others, and the first visit is an assessment rather than a maintenance call. It establishes what is actually installed, its condition, whether the documentation exists, and what needs correcting before we can take responsibility for it.

That report is written to be read by anyone — including the original installer, if they are still contactable and the fault is theirs to fix under warranty. Where we find good work, we say so. Where we find something unsafe, we say so in writing and we say it first.

Energy audits

An audit establishes where energy is actually going, using measurement rather than assumption: consumption profiled over time, major loads identified, tariff and demand charges examined, and power factor measured. The output is a prioritised list — what to fix, in what order, and what it is worth.

It is the honest first step before any recommendation to spend money on generation. Sometimes the cheapest kilowatt-hour is the one that was being wasted, and occasionally an audit ends with a recommendation not to install solar yet.

Power quality and power factor

Poor power factor attracts penalties on commercial and industrial tariffs, and power quality problems cause nuisance tripping, overheating and equipment damage that get blamed on the equipment. Both are measurable. We measure first and recommend after.

Correction is not universal, either. Capacitors improve displacement power factor but do nothing for harmonic distortion, and on a harmonic-rich supply an uncorrected installation of capacitors can make things worse. Measuring first is what separates a fix from an expensive guess. Where the underlying problem is in the installation rather than the load, it belongs with the electrical engineering scope.