BESS FAT and SAT: What EPC Buyers Should Agree Before Delivery

Separate factory evidence from site acceptance

Factory acceptance testing (FAT) addresses the equipment and test configuration available before shipment. Site acceptance testing (SAT) addresses the installed project and its interfaces. A factory report cannot establish that site wiring, metering or external controls operate correctly. Agree which tests belong to each stage and identify the evidence needed before shipment, energization and handover. This is a planning framework, not an executable electrical test procedure.

Write an acceptance matrix

For every contractual requirement record the responsible party, witness, prerequisite, test method, measured signals, pass criterion and report location. For example, a remote dispatch requirement needs an identified command source, response signal, observation period and tolerance agreed by the project team. Do not replace these fields with a generic instruction to check the EMS. Missing tolerances should remain To be confirmed until contract review.

Identify site-specific interfaces

Prepare an interface list covering battery limits, PCS control, revenue or project metering, protection, switchgear, alarms and supervisory communications. Where solar or a generator is included, specify who supplies and validates each control interface. A shared protocol name does not prove model or firmware compatibility. Allocate responsibility for correcting each failed interface before a witness test is scheduled.

Plan performance evidence separately

Define the AC or DC measurement boundary, operating conditions, initial and final battery state, auxiliary treatment and data sampling before comparing a capacity or efficiency result with a guarantee. State which tests are repeated at site and which rely on traceable factory evidence. Guaranteed ratings and tolerances must come from the selected equipment contract, not a generic checklist.

Make handover reviewable

Request the approved single-line diagram, as-built configuration, model and firmware inventory, test reports, unresolved issue list, operating instructions and training records. Assign an owner and closure date to every exception. Document whether an exception prevents acceptance or is permitted under an explicit conditional handover agreement. Preserve the original test data along with the signed summary.

FAQ: Does a passed FAT guarantee backup operation?

No. Backup behavior depends on the installed design and selected equipment. Islanding, load transfer and recovery need their own approved acceptance criteria and site evidence. Work on energized equipment and safety-system tests must be planned and carried out by qualified project personnel under approved procedures.

Source and scope

EPRI identifies commissioning and acceptance testing as part of integration and deployment, with detailed protocols in its referenced ESIC guides. The acceptance matrix above is editorial project-management guidance; it is not an EPRI test protocol or a claim of regulatory compliance.

Sources and scope

• EPRI: Energy Storage Integration and Deployment