BESS availability
The share of committed time the storage asset could actually respond.
BESS availability is the fraction of contracted time the system was able to charge or discharge on demand, excluding downtime from faults, auxiliary failures, or grid issues. Storage revenue — especially in ancillary and capacity markets — is paid for being ready, so availability, usually energy- or capacity-weighted, is a first-order commercial metric, not a footnote.
Definition
Availability measures readiness: the time the asset could deliver its committed power and energy versus the time it was committed. For storage it is often weighted by the value of the windows missed, because an outage during a capacity-market event or a high-price hour costs far more than the same minutes when idle. It is distinct from efficiency — a pack can be fully available yet have poor round-trip efficiency.
Formula
Availability (%) = available (committed) time ÷ total committed time × 100
Typical range
Ancillary- and capacity-market contracts commonly require ≥97–99% availability, with penalties for shortfalls and, in some markets, severe non-delivery charges during called events. Auxiliary (HVAC, PCS) faults are a frequent, under-watched cause of lost availability.
Why it matters
In capacity and ancillary markets you are paid to be ready; a missed dispatch during a called event can cost far more than the energy itself and can damage the asset’s market standing. Tracking availability — and attributing downtime to cause — is how operators protect both the penalty exposure and the revenue.
How NuraVolt tracks it
NuraVolt computes availability from PCS, BMS, and auxiliary status, weights lost time by the market value of the windows affected, and attributes downtime to cause (cell fault, PCS trip, cooling failure, grid) so the costliest readiness gaps are fixed first.
Frequently asked questions
See also
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