On-site inspection and troubleshooting
This page answers one question: when something fails, how quickly does someone arrive — and can they actually fix it?
Most service conversations start with response time. It is the wrong place to start. A four-hour arrival that ends in “we need to order a part and come back” has cost you a truck roll and bought you nothing. What matters is whether the problem is closed on the first visit, and that is decided long before anyone gets in the van.
1. What happens before anyone drives out
Field service on a battery site divides into two lines, and the boundary between them is not seniority — it is whether the work involves opening an enclosure, working live, or replacing a part.
First line is remote. An alarm arrives, someone with access to the monitoring platform reviews the event history, checks whether it is a genuine fault or a parameter threshold that has drifted, verifies the state of the affected string or rack, and where the fault is recoverable, resets it. A significant share of alarms on a healthy site close here.
Second line is physical. A certified technician attends, and from that point the work is governed by electrical safety rules: lockout-tagout, verification of isolation, and the qualifications required for the voltage level involved.
The commercial consequence of that boundary is straightforward. Every fault that first line closes is a truck roll that did not happen. Every fault that first line misdiagnoses is a truck roll that happens twice.
2. Why first-time-fix rate matters more than arrival time
First-time-fix rate (FTFR) is the proportion of work orders resolved on the first visit. It is the single most useful number in field service, and it is rarely the number in the contract.
Published field service benchmarks put the industry average at roughly 75–80%, with best-in-class operations at 88% and above. Performance below 70% measurably erodes SLA attainment and customer retention.
The cost side is equally concrete. Where a first visit does not resolve the fault, the average is approximately 1.6 additional dispatches, at a typical cost of USD 200–300 per truck roll.
Put those together and the arithmetic is unforgiving. A single misdiagnosis at first line costs somewhere between USD 320 and USD 480 in avoidable dispatch cost — before counting the revenue the asset did not earn while it sat down.
What actually drives FTFR
Four factors, in roughly descending order of impact:
| Factor | What it means in practice |
|---|---|
| Spare parts availability | If the part is not in the country, the visit cannot close. This is the most common single cause of a repeat visit, and it is largely determined by decisions made before the fault occurred — see Replacement & spare parts. |
| Diagnostic quality | Whether first line correctly identified what failed. A wrong diagnosis sends the right technician with the wrong part. |
| Work-order completeness | Whether the technician arrives knowing the equipment configuration, firmware version, site access arrangements and safety requirements. |
| Skills matching | Whether the person dispatched holds the qualifications the task requires. A technician who cannot legally open the cabinet has not attended. |
Three of those four are decided before dispatch. That is why we treat remote diagnostics as a cost-control function rather than a convenience.
3. What thermal imaging can and cannot see
Thermal imaging is the most useful non-invasive inspection tool on a battery site, and it is also the most over-claimed.
It can identify:
- Loose or high-resistance connections, which present as localised heating at terminations
- Overloaded conductors and unbalanced loading across phases or strings
- Cell-level hot spots, which are a precursor signature of a failing cell or a degraded connection
- Blocked or failing ventilation and cooling paths, visible as abnormal thermal gradients across an enclosure
It cannot:
- See through an enclosure. A closed cabinet shows you the cabinet’s surface temperature, not the busbar behind it.
- Replace electrical testing. Insulation resistance, earth continuity and protection settings require instruments, not a camera.
- Determine state of charge or state of health. Thermal signature and battery condition are related but not equivalent — see O&M and monitoring for what does measure condition.
The value of a thermal survey depends heavily on how it is performed. Published practice guidance for thermographic inspection of electrical equipment specifies calibration, emissivity settings appropriate to the surface material, instantaneous field of view adequate to resolve the target, and recording of ambient conditions and loading at the time of the survey. A thermal image taken at 20% load tells you very little about a connection that fails at 90%.
4. How a fault is isolated
The sequence below is the standard shape of a corrective intervention on a battery site. The detail varies by equipment and by site rules; the sequence does not.
- Alarm triage. Classify by severity and by whether the condition is self-recoverable, degraded-operation, or stop-immediately.
- Remote review. Event history, affected subsystem, whether related alarms cluster in time or in physical location.
- Isolation of the affected section. Take the affected string, rack or cabinet out of service without dropping the whole site, where the topology allows it.
- Lockout-tagout and verification of isolation. No work begins until isolation is proven, not assumed.
- Physical intervention. Inspection, measurement, replacement.
- Return-to-service testing. The section is proven functional before the alarm is cleared, not after.
- Documentation. What failed, what was done, what was replaced, with serial numbers. This record is not administrative overhead — it is the evidence base for any subsequent warranty claim. See Repair & RMA.
Alongside the electrical sequence sits a fire and safety inspection scope that applies to the enclosure as a whole: enclosure integrity, cable entries and terminations, ventilation, combustible gas detection, and the suppression system. Published fire code frameworks for stationary storage treat these as a standing checklist rather than a one-off commissioning item.
Illustrative scenario
A 25 MWh site in Flanders reports a high-temperature alarm on a single rack at 02:00. First line reviews the event history and finds the alarm is isolated to one module position and has recurred three times over ten days with increasing frequency. The alarm is not self-recoverable and the pattern suggests a degrading connection rather than a control fault.
Rather than dispatching at 02:00 to a site that is otherwise operating, the affected rack is isolated remotely and a visit is scheduled for the following morning with a thermal camera, torque tooling and a replacement module drawn from local stock. The termination is confirmed as the fault source, the connection is remade, the module is inspected and returned to service, and the thermal survey of the adjacent racks is recorded as a baseline.
One visit, one fix, no night-rate call-out — because the diagnosis happened before the dispatch decision.
Illustrative scenario based on typical Benelux configurations — not a client reference.
How we work
Field work on our sites is performed by certified contractors under contract to BessRe. We hold the client relationship, the manufacturer authorisations and the commercial interface. That structure exists for a specific reason: the qualifications required to work on a medium-voltage connection in Belgium are national, and the authorisations required to work on a Chinese-manufactured battery system without affecting its warranty are contractual. They are different things, and both are needed.
Response: 4/8-hour on-site response target across the Benelux, northern France, western Germany, London and Zurich; next-day on-site response across main European markets. Per contracted SLA.
Frequently asked questions
What counts as “response”? It should be defined in the contract, and the definition matters more than the number. Acknowledgement of the alarm, commencement of remote diagnosis, and arrival on site are three different events. We define response as the point at which a qualified person begins working the fault, and we state arrival separately.
How many alarms can be closed remotely? It varies substantially by equipment, site design and how well the alarm thresholds have been tuned after commissioning. Any provider quoting a fixed percentage before seeing your site is guessing. What is stable across sites is the relationship: better remote diagnosis produces fewer repeat visits.
How is first-time-fix rate calculated? The proportion of work orders closed on the first attendance. The definition is only meaningful if “closed” is defined — a visit that leaves the asset in degraded operation pending a part is not a fix.
Do you work on equipment from manufacturers you are not authorised by? We can, and sometimes the situation requires it. But you should know before we start whether doing so affects your warranty position, because on most Chinese equipment it does. See Commissioning for why.
What happens to the part that comes out? It becomes either a warranty claim, a repair candidate, or waste — and each of those has a different documentation and logistics path. See Repair & RMA.
Talk to our team about response requirements for your sites — info@bess.re.
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