Industrial BESS Owner Requirements in Vietnam: A Procurement Brief Bidders Can Price

An industrial BESS owner’s requirement should define the operating problem, point of connection, measurable AC performance, safety interfaces and acceptance evidence before it names a battery capacity. A request that says only “1 MW / 2 MWh lithium battery” invites bidders to price different systems, duty cycles and scope boundaries. The lowest number may therefore be the least comparable offer.

This guide is for an FDI factory owner, project manager, energy manager and procurement team preparing a Vietnam tender. It is not a model selection, a legal approval, a price indication or a construction design. All numerical values are transparent hypothetical inputs that must be replaced by site data and approved engineering.

Prepared for QuangAnhcons · Editorial focus: industrial BESS procurement and factory electrical interfaces · Sources checked: 13 October 2026.

1. Write the business decision as an operating use case

Begin with the decision the battery must support. Peak-demand control, greater use of rooftop PV, ride-through for selected loads and participation in an approved grid service are different use cases. They create different requirements for power, usable energy, response time, state-of-charge reserve and controls. If several use cases are required, rank them and define which function has priority when they compete for the same stored energy.

For each use case, state a measurable success condition, the measurement boundary and the operating exclusions. “Reduce peaks” is not measurable. “Keep 15-minute average import at the agreed point of common coupling below a project-specific limit during the defined production window, subject to an agreed reserve and equipment limits” can be tested. The limit itself must come from the owner’s data and commercial arrangement, not from this article.

2. Define the AC boundary before quoting MW and MWh

A bidder must know where performance is measured. The owner can require active power and usable energy at the AC point of connection, but the contract should then state whether auxiliary loads, transformer losses and cable losses sit inside that boundary. DC cell nameplate energy, cabinet energy and AC-deliverable energy are not interchangeable.

The functional single-line basis should show: utility or industrial-park supply → transformer and main switchboard → factory loads, with the BESS branch comprising battery subsystem → DC protection → PCS → AC protection/transformer as applicable → metering at the agreed point. It should also show rooftop PV, generators, bus ties, normally open points and the control/meter signals used by the energy management system. The final design must be based on the actual site SLD.

Require the vendor to return a boundary drawing with every priced offer. The drawing should mark supply, installation, termination, protection, metering, communication, civil, fire-safety and commissioning responsibilities. A phrase such as “complete BESS” is not a substitute for this boundary.

3. Specify performance with conditions, not brochure maxima

At minimum, define rated charge and discharge power, usable AC energy, permitted SOC window, continuous and short-duration duty, reactive-power capability, ramp limits, response definition, standby and operating auxiliary consumption, round-trip efficiency boundary, availability calculation and degradation treatment. Each figure needs reference conditions: voltage, frequency, temperature, initial SOC, power factor, test duration and data treatment.

Do not turn a manufacturer’s product-page value into a guaranteed project value. For example, Sungrow’s public ST255CS-2H page identifies a 125 kW / 257 kWh product and advertises a 90% system round-trip efficiency for that product family. That page is useful proof that model-specific manuals and boundaries exist; it does not justify using those figures for another configuration or site. The selected vendor must identify the exact hardware, firmware, revision, market version and test method.

Illustrative energy check

Assume the owner wants 1,000 kW of AC discharge for 90 minutes at the agreed delivery point. The required delivered energy is:

E_delivered = 1,000 kW × 1.5 h = 1,500 kWh.

If an illustrative end-of-life usable-energy margin of 15% is applied, the beginning-of-life AC usable-energy requirement would be 1,500 / 0.85 = 1,764.7 kWh. This is a screening calculation, not a battery nameplate selection. The 15% must be replaced by the contracted degradation curve, warranty conditions, SOC window, temperature profile, auxiliary consumption and required reserve.

A separate charging-energy check is also needed. If the contract defines 90% AC-to-AC round-trip efficiency under the relevant cycle, restoring 1,500 kWh of delivered energy would require approximately 1,500 / 0.90 = 1,666.7 kWh at the charging boundary. Do not multiply both margins into one hidden factor; keep performance loss and ageing assumptions visible.

4. Make the duty-cycle schedule part of the tender

Battery life and available energy depend on duty. Provide at least representative weekday, weekend, shutdown and abnormal-day schedules. State expected cycles, depth of discharge, charge source, dwell time, seasonal pattern, number of high-power events and whether the system must preserve an emergency reserve. Ask bidders to identify any use that falls outside their warranty model.

For peak management, supply time-series data at the same interval used by the commercial demand calculation and higher-resolution data where fast control matters. For critical-load support, supply a staged load schedule rather than one aggregate kW value. A 600 kW first step followed by 300 kW after nonessential loads are shed is not equivalent to a continuous 600 kW requirement.

The owner should retain the right to review the dispatch logic, but should not prescribe an unsafe algorithm without full system engineering. The requirement should define outcomes, constraints, fallback states and change authority. The bidder should explain how the controller behaves when the PCC meter, network connection, weather input or remote platform is unavailable.

5. Provide the electrical study inputs and demand study outputs

The RFQ data pack should include the latest controlled SLD, transformer data, cable and busbar information, breaker ratings, protection settings, earthing arrangement, available fault information, generator/ATS logic, PV interfaces, load profiles and planned expansions. Mark every provisional input. The successful designer must verify rather than silently inherit obsolete drawings.

Require a study register, not a generic promise to “perform all studies.” Depending on the actual connection, the register may include load flow, short-circuit cases, protection coordination, cable/transformer loading, voltage change, harmonics, reactive power, earthing, arc-flash assessment, control interaction and islanding or reconnection studies. The applicable scope should be decided from the site topology and serving-entity requirements.

Use the existing factory fault-case register guide to separate maximum breaking-duty cases from minimum-fault sensitivity. The P/Q load-schedule guide explains why imported machine ratings and operating scenarios must be consolidated before a BESS is added to the factory model.

6. Separate system safety from component certificates

IEC 62933-5-2:2025 Edition 2.0 addresses safety requirements for grid-integrated electrochemical electrical energy storage systems. Its public IEC catalogue scope supports a system-level safety approach across interacting subsystems and the lifecycle. A cell, module, PCS or enclosure certificate does not by itself prove the safety or compliance of the installed BESS.

The owner’s requirement should call for a project hazard register covering electrical shock and arc hazards, thermal propagation, fire detection and response interfaces, ventilation or gas management where relevant, emergency isolation, re-energisation control, access, drainage, flooding, corrosion, lightning, earthing, mechanical impact, lifting, transport and end-of-life handling. It must assign decisions to competent project parties and the authorities having jurisdiction.

Ask each bidder for the safety design basis, listed evidence, residual risks, emergency-response inputs and site conditions on which the proposal depends. Do not request copied paid-standard clauses. Require the tenderer to identify editions and show how project deliverables demonstrate the selected requirements.

7. Keep Vietnam legal and utility interfaces explicit

The contract should have a legal-and-approvals register prepared for the specific location and operating mode. Vietnam’s Circular 05/2025/TT-BCT governs transmission, distribution, electricity metering and connection matters within its scope and has later amendments that the project team must check. It is not a product specification for every factory BESS. The serving utility or industrial-park entity may also have project-specific data, protection, metering and switching requirements.

Separate four layers: binding Vietnamese law and QCVN within their actual scope; selected TCVN/IEC design standards; serving-entity requirements for the specific connection; and OEM instructions for the exact supplied equipment. Record document number, edition, amendment, applicability decision, source and responsible reviewer. Do not write “complies with IEC/TCVN/EVN” as a blanket statement.

8. Allocate civil, fire, HVAC and operational interfaces

The owner brief should provide site coordinates, layout, access route, lifting restrictions, geotechnical information if available, flood level, drainage, ambient conditions, dust/corrosion classification, nearby occupied areas and planned expansion. The bidder should return equipment loads, footprint, clearances, heat rejection, drainage, cable entry, foundation reactions, access and replacement paths.

Use the electrical design responsibility matrix to name the producer, technical checker, decision-maker and input owner for every deliverable. For quantity and scope preparation, the electrical survey and BOQ service page shows how to separate observed conditions, design decisions and provisional quantities.

9. Define EMS, SCADA and cybersecurity outcomes

State who controls active and reactive power, where the PCC signal originates, how commands are prioritised and what happens when communications fail. Require a signal list, protocol register, time-synchronisation method, historian retention, event resolution, user roles, remote-access boundary, backup/restore process and change-management procedure.

Do not put passwords or live network details in the tender. Describe the architecture and access workflow at a level that lets bidders price gateways, licences, testing and support. Require the successful supplier to deliver a point-to-point test, alarm matrix, control narrative, version register and recovery test. Cloud access should not become an undocumented dependency for a safety-critical local function.

10. Turn warranties into measurable acceptance obligations

A useful warranty schedule defines what is warranted, where it is measured, reference conditions, exclusions, evidence, test frequency and remedy. Separate equipment defects, system availability, usable energy, power capability, efficiency and service response. Ask the bidder to provide the degradation curve and duty assumptions behind any retained-capacity guarantee.

For availability, define numerator and denominator, excluded planned outages, grid outages, owner-caused restrictions, data gaps and partial derating. For usable energy, define initial SOC, final SOC, AC boundary, stabilisation, auxiliary loads and correction method. An acceptance test must not use a different boundary from the commercial guarantee.

Require a bid-return matrix so every tenderer responds to the same fields:

• exact equipment and software versions, quantities and supply boundary;
• AC power, usable energy and reactive capability at stated conditions;
• efficiency, auxiliary consumption and degradation assumptions;
• duty-cycle and warranty limits, exclusions and remedy;
• electrical, civil, fire, HVAC, controls and communications interfaces;
• FAT, site inspection, SAT, performance test and reliability-run evidence;
• training, spares, maintenance tools, licences, remote support and end-of-life obligations;
• assumptions, deviations, unresolved inputs and options priced separately.

11. Build a staged FAT–SAT–performance acceptance plan

Factory acceptance should verify the agreed equipment and functional baseline without pretending to reproduce the complete site. Site acceptance should verify installation, protection, interlocks, communications, metering, emergency functions and operating modes at the real interfaces. The performance test should then demonstrate the contracted power, usable energy or other KPI at the defined boundary and conditions.

Hold points should cover design-basis approval, long-lead release, civil readiness, equipment receipt, pre-energisation review, first energisation, functional tests, performance acceptance and handover. Each hold point needs an authorised release record. A successful subsystem test is not proof that the complete BESS, factory protection and operating logic work together.

12. Use a realistic procurement WBS

No universal duration is stated because permitting, measurement periods, vendor lead time, shutdown access and authority review depend on the project. Bidders should return their calendars, predecessors, owner inputs and hold points. The owner can then compare schedule logic rather than an unsupported completion date.

13. Final owner checklist before issuing the BESS RFQ

• Ranked use cases and measurable KPIs are approved.
• The AC performance boundary and PCC are shown on a controlled SLD.
• Load, PV, generator and planned-load data are time-aligned and qualified.
• Power, energy, SOC, duty and reserve requirements use consistent units.
• Study inputs, operating modes and protection interfaces are listed.
• Legal, QCVN/TCVN/IEC, utility and OEM documents are separated by scope and edition.
• Site, logistics, civil, fire, HVAC and emergency-response interfaces have named owners.
• EMS/SCADA/cybersecurity outcomes and fallback states are defined.
• Guarantees state boundary, conditions, exclusions, evidence and remedy.
• FAT, SAT, performance testing, training and handover records are priced.
• Every bidder returns assumptions, exclusions and deviations in the same matrix.

Next step: issue a controlled data-room index with the draft owner requirement, SLD, time-series data, site information and open-item register. Ask the design and procurement teams to close boundary and applicability questions before evaluating prices. That process produces a defensible technical comparison without pretending that a generic MW/MWh ratio is a complete design.

Sources and applicability ledger

The worked values—1,500 kWh, 1,764.7 kWh and 1,666.7 kWh—were independently recomputed from the explicitly stated hypothetical inputs. They are not project data, prices, savings, warranty promises or approved equipment ratings.

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