O&M, monitoring and diagnostics

This page answers one question: who is watching the asset day to day, and will they see a problem before it becomes an outage?

There are three separate things hidden inside that question, and conflating them is the most common mistake in storage O&M procurement. Preventive maintenance is what people do on site. Monitoring is what records and displays. Diagnostics is what independently determines the asset’s condition. Buying one and assuming you have the other three is how owners end up with a dashboard full of green lights and a battery they cannot make a warranty claim on.

1. What a preventive maintenance plan actually contains

Periodicity varies by manufacturer manual and by risk classification. The scope does not vary much.

The last row is not administrative. It is the file you will need if you ever have to prove that the asset was maintained in accordance with the warranty terms.

2. The monitoring account should sit with the owner

This is our clearest recommendation and it is the one that reduces our own commercial lock-in, so take it at face value.

Published guidance from DNV on battery storage data management states that second-by-second BMS data should be held by the owner or a neutral third party, to serve as the factual basis in a dispute.

That is not a preference. It is a recognition that when a warranty claim, a performance dispute or an insurance question arises, the data is the evidence — and evidence held solely by one of the interested parties is worth less than evidence held neutrally.

The architecture that follows is simple:

• The platform account is in the owner’s name.
• Field execution — ours or anyone else’s — receives work orders through that platform rather than operating it.
• The owner retains the data history across any change of service provider.

This is not theoretical. On a Dutch grid-scale storage project, the asset owner and the O&M provider hold parallel views of the same asset on the same platform, with visibility extending to how the third-party trading party is dispatching the battery. The architecture works in production.

Several platforms support it directly. Vendor-neutral acquisition and ticketing platforms offer owner-held accounts with controlled sharing to external partners, and work-order management designed for exactly this arrangement.

Choose whichever platform fits your requirements. Our recommendation concerns whose name is on the account, not which logo is on the screen.

3. Monitoring is not diagnostics

A monitoring platform records what the equipment reports. A diagnostic layer determines independently what the equipment’s condition actually is. The difference is not academic.

Published comparison work is unambiguous on one point: BMS-reported state of health frequently carries no information. In documented field comparisons the BMS-reported figure remained at 100% throughout the observation period while the battery was measurably ageing — whereas an independent physics-based model tracked the true degradation to within approximately 1%.

The implication for an owner is direct. If your evidence of asset condition is the number the BMS reports, you may have no evidence at all. And state of health is precisely the parameter that capacity warranties are written against.

Both layers are needed. They are not substitutes, and a platform that does one well should not be assumed to do the other.

4. Warranty envelope management

This is the part of storage O&M that most directly touches revenue, and it is the least often contracted for.

Battery warranties are written against operating limits. Published guidance identifies five recurring categories:

1. Average state of charge over the year, commonly capped below 50%
2. C-rate window, commonly in the region of 0.25C to 1C
3. Ambient or container temperature, commonly around 25°C
4. Energy throughput and cycle count limits
5. Calendar ageing, running regardless of use

Now set that against how these assets are actually being operated. In the UK market, average daily cycling rose from roughly 0.1 cycles per day to approximately 0.8 within two years, with assets in the Dynamic Regulation service reaching as high as 2.84 cycles per day.

The tension is not subtle. Trading revenue increases with harder operation. Warranty cover decreases with it. Somebody has to manage that boundary, and on most sites nobody does — the trading party optimises revenue, the EMS executes, and the warranty terms sit in a folder.

This is where a party who holds both the manufacturer relationship and the diagnostic data can do something neither the trader nor the O&M contractor can do alone:

• Establish where the actual operating envelope sits, evidenced rather than assumed
• Document operation against it continuously, so that the record exists before a dispute does
• Where the diagnostic evidence supports it, take a case to the manufacturer for a wider envelope — because a manufacturer presented with independent condition data is in a different conversation from one presented with a request

A wider envelope is additional revenue. It is also the only part of this work where a share of the upside is a coherent commercial structure, because it is the only part where the upside would not otherwise exist.

Illustrative scenario

A Flemish owner operating behind-the-meter storage on its own balance sheet earns from trading and flexibility. Availability translates directly into revenue, so the O&M contract is written with an availability-linked component.

The monitoring account is held in the owner’s name on a vendor-neutral platform. Field execution receives work orders through it. A diagnostic layer sits above it, estimating capacity fade independently of the BMS.

After eighteen months the diagnostic layer shows measured degradation materially below the warranty’s assumed curve, while the BMS continues to report 100% state of health. The owner’s trading team wants to increase cycling. Rather than doing so and hoping, the operating envelope question is put to the manufacturer with eighteen months of independent condition data attached.

Whatever the manufacturer decides, the owner is making the decision with evidence rather than without it — and the evidence exists because somebody set the architecture up correctly at commissioning.

Illustrative scenario based on typical Benelux configurations — not a client reference.

How we work

We recommend the monitoring account sits with you, and we mean it — it makes us easier to replace. We separate acquisition from diagnostics because they answer different questions. We read your warranty operating limits before proposing an O&M scope. And field work is performed by certified contractors under contract to BessRe, with us holding the client relationship, the manufacturer authorisations and the commercial interface.

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

Who should hold the monitoring account? You should. Published DNV guidance recommends that BMS data be held by the owner or a neutral third party to serve as the factual basis in a dispute. It also means you keep your data history if you change providers.

Can I rely on the state of health my BMS reports? Treat it with caution. Documented field comparisons record BMS-reported state of health remaining at 100% while measurable ageing was occurring. Since capacity warranties are written against state of health, this matters.

Will cycling harder void my warranty? It depends on your specific terms, and the limits are usually more restrictive than owners expect — average state of charge, C-rate window, temperature, throughput and cycle count. The answer for your asset is in your own contract, and it is worth establishing before the trading strategy is set.

Do I need both a monitoring platform and a diagnostic layer? They answer different questions. Monitoring tells you something failed. Diagnostics tells you what condition the asset is in — which is what a warranty claim, an insurer or a refinancing will ask about.

Can our O&M provider use our platform rather than their own? Yes, and we would encourage it. Platforms built for this arrangement provide controlled external partner access and work-order dispatch to third parties as standard functionality.

Talk to our team about O&M scope and monitoring architecture for your assets — info@bess.re.

Repair or Replace? The 2026 EU Compliance & Local Delivery Guide

Repair economics, the compliance map, and local delivery capability — for Chinese BESS manufacturers entering Europe.

Download the whitepaper →