Availability guarantee

An availability guarantee is a promise in an O&M contract that the PV plant will be available for at least a minimum share of the time, or of the energy it could produce. After the guaranteed performance ratio, guaranteed plant availability is the most common guarantee in solar O&M contracts, and best practice is to use both together. SolarPower Europe recommends a minimum guaranteed contractual availability of 98% over a year, measured at least at the inverter level. Where full-time staff must be on site, as in Mexico, 99% can be offered. The IEA PVPS guidance says most guidelines set guaranteed plant availability at 99% or higher, because the grid side is outside the operator's control. Contractual availability excludes downtime the O&M provider is not responsible for, such as force majeure, grid operator curtailment and grid instability. Failure time starts only when the provider receives the error message. Availability can be measured by time, using inverter data above an irradiance threshold, or by energy. The energy-based method counts the lost energy, so an outage in strong sun weighs more. If measured availability falls below the guarantee, the provider repays the lost revenue as liquidated damages. If it exceeds the guarantee, a bonus scheme splits the extra revenue between owner and provider. Yearly liquidated damages should be capped at 100% of the annual O&M fee. Reaching the cap usually gives the right to terminate the contract.

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• sentence 4: support check: partial - The 99% or higher recommendation and the grid being beyond operator control are in the passages, but the passages do not say the grid is the reason for the 99% level, and the IEA PVPS attribution is not stated.
• sentence 7: support check: partial - The bonus split is stated, but the LD condition is garbled as 'Minimum Guaranteed Availability is less than measured', which is the reverse of the statement's below-guarantee trigger. The surrounding text implies compensation for lower-than-guaranteed availability.
• sentence 4: review: partial - The passage gives the 'at least 99%' recommendation and says the grid is beyond the operator's control, but it uses the grid point to explain why plant-level availability is the KPI that matters, not why the level is set at… -->