Availability Guarantee
Definition
An availability guarantee is a commitment, usually by the equipment supplier, builder or maintenance contractor, that a plant or battery will be available to operate for at least a set percentage of the time, measured over a year or another period. If availability falls short, the contractor pays liquidated damages, typically a percentage of the contract price or a set amount per point of shortfall, often up to a cap. It protects the owner against equipment downtime, not against weak sun, wind or market prices.
Why it matters
For investors, an availability guarantee moves part of the cost of equipment failures from the project to the contractor. Its value depends on the threshold, what counts as unavailable, the size and cap of the damages and the contractor's ability to pay. Under capacity-based contracts such as battery tolls, availability is often what the project is paid for, so the guarantee can protect revenue directly.
Common misconceptions
- •An availability guarantee does not guarantee output or revenue; weather and prices are excluded.
- •Liquidated damages are usually capped and may cover only part of lost revenue.
- •The guarantee is only as good as the contractor's credit and the length of the guarantee period.
- •The label is only a starting point. Investor outcomes usually depend on the governing documents, cash-flow priority, valuation policy, disclosure quality, and manager discretion surrounding the term, not just the shorthand definition used in marketing materials.
Technical details
Worked example: Ameresco and Southern California Edison (EX-10.10, filed March 1, 2022)
Measure: annual equivalent availability (AEA) of the energy storage system.
Requirement: AEA of 97%.
Liquidated damages: 0.2% of the total EPC price for each whole 1% below the requirement.
A separate Energy Capacity Guarantee applies during the contract's fixed energy capacity service package.
Questions to ask
What is excluded from the availability calculation (grid outages, force majeure, owner-caused downtime)?
Are damages capped, and at what share of the contract price?
How long does the guarantee last relative to the debt and the offtake contract?
Who guarantees the contractor's obligations?
How investors apply the term
Investors usually apply this term by tying the definition back to the controlling documents and then asking which cash flows, rights, restrictions, or valuation assumptions it changes. A useful review looks at the term alongside fees, leverage, liquidity, reporting frequency, and manager discretion rather than treating it as a standalone concept.
The practical diligence test is simple: identify who benefits if the assumption is wrong, who has control when conditions change, and what evidence the investor receives after closing. Terms that cannot be reconciled to documents, cash movements, and monitoring data should be treated as marketing shorthand until proven otherwise.
Frequently asked questions
- What does a real availability guarantee look like?
- Ameresco's engineering, procurement and maintenance contract with Southern California Edison for battery storage (filed as an exhibit in 2022) sets an annual equivalent availability requirement of 97%, with liquidated damages of 0.2% 'of the total EPC Price ... per each whole one (1) percent below the AEA Requirement.' It adds that planned maintenance 'will count against availability, the same as unexpected down time.'
- Does planned maintenance count as unavailable?
- It depends on the contract. Many exclude scheduled maintenance; the Ameresco contract counts it, which is why the requirement 'already provides for planned maintenance.'
- How does availability differ from capacity factor?
- Availability measures the share of time equipment is ready to run; capacity factor measures output. Clearway reported a 93.4% equivalent availability factor for its gas-fired Flexible Generation fleet in 2025, a fleet that ran far less than that.