Insurance is usually the last conversation on a storage project and occasionally the one that stops it. Developers who have financed solar are sometimes surprised to find that a battery is not treated as more electrical plant on the same site — it is underwritten as its own risk class, with its own questionnaire, its own exclusions and its own loss history behind it.
Understanding what the underwriter is worried about is the cheapest way to get a better rate.
The three covers
A storage project generally needs three distinct things, and it is worth knowing which is which because they are frequently confused.
Business interruption deserves a mention of its own. On a contracted project, the equipment loss from a container fire may be modest next to the revenue lost while the asset sits offline waiting for replacement modules. That downtime exposure is frequently the bigger number.
What underwriters are actually worried about
The exposures insurers price for in storage are specific, and they are not the ones a general property underwriter would guess.
Thermal runaway propagation. This is the dominant concern. A single cell failing is a contained problem; a single cell failing and taking the module, then the rack, then the container with it is a total loss plus a long outage. Propagation — not ignition — is what turns an incident into a claim. Our article on fire safety and thermal runaway explains the mechanism and the design responses.
Chemistry. Rates have generally been firmer on NMC (nickel manganese cobalt) installations than on LFP (lithium iron phosphate), reflecting the different failure behaviour of the two chemistries. If you want the underlying reasons, see our LFP versus NMC comparison.
BMS failure. Battery management system failure at behind-the-meter installations is an explicitly recognised exposure. The control layer that is supposed to catch an unsafe condition is itself a single point of failure — see our guide to what a BMS does.
Siting and proximity. How close the containers sit to each other, to the boundary, and to whatever else is on the site. Separation distance is one of the levers a developer genuinely controls, and it interacts directly with the land you need.
Alongside those, underwriters assess technology maturity, fire safety protocols, operational experience and regulatory compliance when deciding whether and how to write the risk.
The market has been getting harder, not softer
This is the part worth planning around. As international loss experience accumulated through the storage build-out, underwriting tightened: policy wordings were adjusted, available capacity was moderated on the most exposed installations, and rates firmed — particularly on NMC deployments.
The practical consequence is that a project cannot assume yesterday’s terms. Insurance should be scoped early enough that a difficult answer does not arrive after financial close.
How to get a better rate
Underwriters price uncertainty. Most of what improves a rate is documentation you should have anyway:
- Test evidence against recognised standards. Compliance with the standards we cover in BESS safety standards explained — particularly large-scale fire testing — is close to a threshold requirement, not a bonus.
- A written fire protection design, including detection, suppression, separation distances and what happens after an event.
- An emergency response plan agreed with the local fire service, not filed in a drawer.
- Monitoring, with evidence that alarms reach a human who can act. Operators with robust monitoring have generally been better placed on premium.
- A clear operating and maintenance regime — insurance is one of the four operating cost buckets covered in our guide to BESS O&M costs, and the others affect it.
What this means for you
- If you are a developer or IPP: engage a broker who has placed storage before, and do it at design stage rather than at financial close. Separation distances and suppression choices are cheap to change on a drawing and expensive to change on a site.
- If you are a C&I buyer: ask your supplier what standards the system has been tested to and what fire protection is included. Then tell your existing property insurer what you are installing, before you install it — an undisclosed battery on a covered site is a claims dispute waiting to happen.
- If you are comparing quotes: the cheapest system may carry the most expensive insurance, and over fifteen years that gap can erase the saving. Look at the total, including the cover.
Insurance market conditions, available capacity and pricing move with loss experience and vary by insurer, site and chemistry — nothing here is a quotation or a substitute for advice from a licensed broker or insurer. Treat this as an August 2026 snapshot of market practice and confirm current terms with your own advisers. You can see the safety design behind our standalone storage systems and the ADESS 6500 container system, or get in touch with our team to discuss a specific site.