Two-part tariff for factories: load factor decides winners and losers
Pilot membership is near-automatic for any factory above 200,000 kWh/month at 22 kV+. But being in the pilot tells you which pricing structure applies — it does not tell you whether your bill goes up or down. Load factor does.
Page current as of 23 April 2026. Anchor regulation: Decree 146/2025/NĐ-CP, real-money billing from 1 July 2026. Shadow billing active for pilot cohort since 1 January 2026. See the full two-part tariff explainer.
Am I in the pilot? And does it matter?
Yes, you are probably in the pilot — but that is the wrong question. Pilot inclusion is mechanically easy to check. The question that matters is whether your bill goes up, down, or stays flat under the new structure. Load factor answers it.
Pilot eligibility is defined by two thresholds in Decree 146/2025/NĐ-CP: an average monthly consumption of ≥200,000 kWh and a connection voltage of ≥22 kV. Any factory that meets both is in from 1 July 2026; the formal pilot runs through 31 July 2027, with nationwide manufacturing expansion from August 2027. A 1.5 MW single-site manufacturer drawing ~720,000 kWh/month is three-and-a-half times the threshold. A 5 MW multi-shift facility drawing ~2.4 GWh/month is twelve times the threshold. Most Arcus factory prospects are well inside the pilot; the few that are not will enter by 2027.
What pilot inclusion does not tell you is whether the new structure is better or worse for your specific load profile. Vietnam's ~7,000 pilot manufacturers do not experience a uniform +x% or −y% bill change. They split into three outcomes, driven primarily by load factor — the ratio of average demand to peak demand over a month. Continuous-process manufacturers running flat 24/7 loads at 70%+ load factor typically save modestly under the new structure; discrete batch operators running single-shift peaky production at sub-55% load factor typically pay more; factories between those limits are roughly flat.
In practice: before booking a BESS session with your CFO, run the load-factor calculation. If you are above 70% and your bill falls under the pilot, BESS adds incremental value but is not urgent. If you are below 55%, BESS peak-shaving is a direct counter-measure to a real bill increase, and the urgency is high. If you are in the 55–70% band, the BESS case is sound but rests on energy arbitrage and reserve capacity, not on flipping a loss to a gain.
The three segments of the pilot cohort
Rough split across the ~7,000 pilot manufacturers, based on industry-level load-factor averages. Precise proportions depend on EVN's published pilot-cohort composition, which will refine as shadow-billing data is analysed through 2026.
Flat-load continuous process
Load factor typically 70–85%
Cement, steel, chemicals, paper, glass, semiconductor fabs — three-shift continuous operations with high baseload and small peak-to-average swings. The energy-rate cut (~30–35%) outweighs the new capacity charge at a high load factor.
Typical bill outcome: 5–12% monthly reduction.
Mid-profile multi-shift
Load factor typically 55–70%
Consumer electronics assembly, food & beverage, mid-size textile, plastics and packaging. Two-shift or partial three-shift operations with moderate peak-to-average swing. Energy-rate cut and capacity charge roughly balance.
Typical bill outcome: ±3% of current bill.
Peaky batch operations
Load factor typically 35–55%
Automotive parts (stamping, forging, welding), discrete metalworking, single-shift textile, seasonal food processing. Low baseload, short high-intensity demand spikes. Pays full capacity charge for a peak it hits briefly.
Typical bill outcome: 8–18% monthly increase.
4.1 · Why load factor drives the outcome
The two-part tariff's structural logic is cost-reflective pricing: the grid incurs a mix of capacity costs (transformers, lines, substations sized to serve peak demand) and energy costs (fuel, transmission losses). Under the single-part tariff, both are recovered through a VND/kWh charge — which means high-load-factor customers over-pay and low-load-factor customers under-pay for the capacity they actually cause EVN to build. The two-part tariff separates the recovery mechanisms so each type of cost is paid by the customers who drive it.
A flat-load factory of given size at high load factor imposes lower per-kW capacity cost on the grid because it uses its reserved capacity most of the time. A peaky batch factory imposes the same per-kW capacity cost but uses its reservation briefly; it has been paying less than its fair share under the single-part tariff. The two-part tariff corrects this. From EVN's cost-recovery perspective it is a rationalisation; from the peaky factory's perspective it is a bill increase.
In practice: this is the policy mechanism behind Politburo Resolution 70-NQ/TW's call for cost-reflective pricing. The direction of travel across the 2028–2030 rollout is toward more, not less, cost-reflectivity. Factories in the loser segment today should model BESS on a multi-year payback with confidence that the capacity-charge rate is anchored, not at risk of being reversed by a pricing reform in the opposite direction.
4.2 · Where BESS peak-shaving flips the sign
At 22 kV manufacturing, the capacity charge is VND 235,414/kW/month — approximately VND 2.82 million per kW per year, or USD 110/kW-year at April 2026 FX. A loser-segment factory with a sharp 500 kW peak twice a week, shaved to a flat baseline via a modestly-sized BESS, reduces its registered Pmax by 500 kW permanently and saves ~VND 1.41 billion/year (≈ USD 55,000/year) in capacity-charge alone. That is roughly the order of magnitude that flips a loser-segment bill increase back to break-even or modest gain.
BESS sizing follows from the Pmax reduction target, not from a stock sizing table. A factory identifying a 500 kW shave need only enough battery power to cover the peak-shave ramp and enough energy to hold the shave through the peak event window. For a typical manufacturing peak of 60–90 minutes, a 500 kW / 1,000 kWh BESS (2-hour duration) is usually sufficient; durations longer than this add capex without meaningful capacity-charge benefit, though energy-arbitrage revenue then layers on top independently.
In practice: a loser-segment factory should treat BESS as a bill-repair investment, not a bill-optimisation investment. The economic case does not require energy arbitrage to work; capacity-charge reduction alone typically delivers a 3–4 year payback at current capex. Energy arbitrage is the bonus.
Two-part tariff terms most relevant to factory operators
The anchor page covers the full Decree 146 framework. Below is the narrow slice a factory operator needs in negotiation with EVN and in BESS vendor briefings.
- Pmax declaration and true-up The customer declares a registered maximum demand in kilowatts when entering the pilot. Each month the customer is billed Pmax × VND 235,414 (at 22 kV) regardless of whether the peak is hit. Exceeding declared Pmax triggers penalty charges; consistently undershooting allows renegotiation downward at agreed review points. For BESS-equipped factories, the right strategy is to declare Pmax at the post-shave level and commit operationally to holding it — this captures the full capacity-charge saving without triggering penalty risk.
- Pilot energy rates (sub-Decision 1279) The pilot energy component is approximately 30–35% below today's single-part rates: roughly VND 843–904/kWh off-peak, VND 1,253–1,332/kWh standard, VND 2,162–2,251/kWh peak. The peak-to-off-peak spread compresses from VND 2,208/kWh today to approximately VND 1,300/kWh under the pilot — a ~41% narrowing that reduces energy-arbitrage revenue proportionally.
- Capacity charge by voltage band VND 209,459/kW/month at ≥110 kV, VND 235,414/kW/month at 22 kV–<110 kV, VND 240,050/kW/month at 6 kV–<22 kV, VND 286,153/kW/month at <6 kV. Higher voltage connections pay less per kW because they use fewer downstream transformation stages. For factories considering a voltage upgrade from 22 kV to 110 kV as part of a site expansion, the capacity-charge differential is a new economic input worth modelling alongside connection cost.
- Decree 57 DPPA double-charging risk Factories that also offtake under a grid-connected (Model 2) DPPA face a known double-charging risk. The capacity charge under Decree 146 and the CDPPA grid service charge under Decree 57 both recover grid-infrastructure costs. Norton Rose Fulbright confirmed in January 2026 that DPPA offtakers will likely still pay the full capacity charge until the amending decree to Decree 57 resolves the overlap. Any DPPA term sheet signed in 2026 should include change-in-law protection — see the Decree 57 spoke for more on the hedge-math interaction.
- MOIT 15 April 2026 TOU consultation MOIT published a draft TOU-window restructuring on 15 April 2026; EVN submitted a counter-proposal. Both eliminate the 09:30–11:30 morning peak. Under EVN's counter-proposal (single 17:30–22:30 evening peak), BESS peak-shaving becomes more valuable because a continuous 5-hour evening block is more efficient to dispatch than today's split peak. Under MOIT's seasonal proposal, the May–August 19:30–22:30 evening-peak slot is pure BESS territory that solar cannot serve. Either outcome strengthens the BESS case for factory peak-shaving.
Worked example — a peaky automotive parts manufacturer, 22 kV, 850 MWh/month
A two-shift automotive parts factory in Bình Dương, 22 kV, load factor 48%
Setup
- SectorAutomotive stamping & welding (tier-2 supplier)
- Monthly consumption~850,000 kWh/month (well above the 200,000 kWh pilot threshold)
- Voltage22 kV connection
- OperationTwo shifts × 5 days/week; single-shift Saturday; idle Sunday
- Pmax, no BESS2,450 kW (stamping press startup spike, ~08:30–10:00 daily)
- Average demand~1,180 kW (850,000 kWh / 720 hours)
- Load factor~48% — loser segment
- BESS considered600 kW / 1,200 kWh behind-the-meter, configured for morning peak-shaving
Monthly bill scenarios (VND million, rounded)
| Component | Today (Dec. 1279) | Pilot, no BESS | Pilot + 600 kW BESS |
|---|---|---|---|
| Energy — peak (25% of consumption) | 722 | 469 | 469 |
| Energy — standard (60% of consumption) | 935 | 661 | 661 |
| Energy — off-peak (15% of consumption) | 152 | 111 | 111 |
| Capacity charge (Pmax × 235,414) | — | 577 | 436 |
| Total monthly bill | 1,809 | 1,818 | 1,677 |
| Δ vs today | — | +0.5% | −7.3% |
Interpretation
Without BESS, this loser-segment factory is approximately flat under the pilot — the ~48% load factor sits on the boundary between break-even and loss. A facility at 40% load factor in the same sector would see a clearer 8–12% bill increase; this 48%-load-factor example is near the break-even line already, which is why the pilot-without-BESS delta is small (+0.5%). The economic story is not "the pilot destroys this factory" but "the pilot removes the cross-subsidy this factory used to receive."
With a 600 kW / 1,200 kWh BESS shaving Pmax from 2,450 kW to 1,850 kW (a 600 kW reduction), the capacity-charge line drops by VND 141m/month — VND 1.69bn/year (≈ USD 67,000/year) in capacity-charge saving alone. Total monthly bill falls to VND 1,677m, a 7.3% reduction against today — meaning the factory ends up net better-off under the pilot with BESS than it is under today's single-part tariff without BESS.
In practice: BESS capex at USD 190/kWh behind-the-meter convention gives a 1,200 kWh system at approximately USD 228,000. Simple payback on the capacity-charge saving alone is roughly 3.4 years. Energy arbitrage — charging at off-peak, discharging on second peak event — adds a further USD 12,000–18,000/year depending on dispatch frequency, shortening payback toward 3 years combined.
Source: Arcus Energy illustrative scenario, figures rounded. Pilot energy rates modelled at the midpoint of the VND 843–904, 1,253–1,332, 2,162–2,251 ranges reported by EVN. Capacity-charge rate per Decree 146/2025/NĐ-CP at 22 kV. Pmax shave assumes BESS sized to cover the highest of two daily peak events within a 90-minute window; see anchor page §Worked example for a flat-load alternative archetype.
Three steps to diagnose your segment before booking BESS analysis
A plant manager with a recent EVN bill, a spreadsheet, and fifteen minutes can self-diagnose which pilot segment their factory falls into. The BESS sizing conversation begins after this — not before.
- Pull your last 12 monthly bills and extract peak demand (kW) and consumption (kWh) for each. Every TOU-metered EVN bill shows both figures. If your meter records 30-minute demand data, you can reconstruct a finer peak profile; if it only records monthly Pmax, that is sufficient for this step.
- Calculate monthly load factor. The formula: Load factor (%) = (monthly kWh ÷ 720 hours) ÷ peak kW × 100 Average the twelve monthly values. A 12-month rolling average smooths out seasonal spikes (Tết shutdown, summer cooling load) that can mislead a single-month read. If your consumption is highly seasonal, separate the high-production months from the low-production months and calculate both — BESS sizing needs to hold in the high-production months.
- Map to segment. Above 70%: winner segment. The pilot reduces your bill modestly; BESS adds incremental value via energy arbitrage but is not urgent. 55–70%: break-even. BESS case rests on energy arbitrage plus a smaller Pmax shave; payback typically 5–6 years. Below 55%: loser segment. BESS peak-shaving is the primary re-sorting tool; payback typically 3–4 years on capacity-charge saving alone. The steeper your fall below 55%, the stronger the urgency.
In practice: if you emerge as a winner-segment factory, do not rush to BESS — focus on solar (see /solutions/factories) and revisit BESS in 2027–2028 as the energy-rate spread and Pmax profile evolve. If you emerge as loser-segment, the urgency is commercial, not regulatory: every month of delay after 1 July 2026 is a real bill increase flowing out the door.
Frequently asked questions
Is my factory in the two-part tariff pilot?
If your factory consumes at least 200,000 kWh per month on average at a connection voltage of 22 kV or higher, yes. That threshold covers approximately 7,000 Vietnamese manufacturing customers. Real-money billing began on 1 July 2026 for this cohort; the formal pilot runs to 31 July 2027 with nationwide manufacturing expansion from August 2027 and broader C&I rollout through 2028–2030. Facilities below 200,000 kWh/month or below 22 kV are excluded from the pilot but should expect entry during the later rollout.
Does being in the pilot mean my bill goes up?
Not necessarily. Pilot membership tells you which pricing structure applies — it does not tell you whether the new structure is better or worse for your specific load profile. Factories with flat, high-utilisation loads (continuous process industries, three-shift operations at steady baseload) typically see a modest bill reduction because the energy-rate cut outweighs the new capacity charge. Factories with peaky, low-utilisation loads (single-shift batch operators, seasonal production) typically see a bill increase. Load factor — average demand divided by peak demand — is the diagnostic.
What is load factor and how do I calculate mine?
Load factor is your average monthly kW demand divided by your peak monthly kW demand, expressed as a percentage. Formula: (monthly kWh / 720 hours) / peak kW × 100. A factory running at 1,000 kW peak with 500,000 kWh monthly consumption has an average demand of ~694 kW and a load factor of 69%. Above 70% is generally winner territory under the two-part tariff; below 55% is generally loser territory; 55–70% is break-even. The lower your load factor, the more you benefit from BESS peak-shaving — because there is more peak to shave relative to average demand.
How much does BESS peak-shaving save under the two-part tariff?
At 22 kV manufacturing, every kilowatt shaved from registered Pmax saves VND 235,414 per month — approximately VND 2.82 million per kW per year, or roughly USD 110 per kW-year at April 2026 FX. A 500 kW Pmax reduction through behind-the-meter BESS delivers approximately VND 1.41 billion in annual capacity-charge saving. At a behind-the-meter C&I BESS all-in cost of USD 190/kWh (Arcus convention, April 2026), a 500 kW / 1,000 kWh battery costs approximately USD 190,000; capacity-charge-only payback is roughly 3.4 years before energy-arbitrage revenue is layered on. The combined payback typically lands in the 4–6 year range, depending on load-profile specifics.
Should I still install solar if the two-part tariff is coming?
Yes — and for factories on manufacturing tariff, solar remains the lead asset with BESS layered on top. The two-part tariff narrows the peak-to-off-peak energy spread by ~35–40%, which reduces the arbitrage component of BESS revenue, but it simultaneously creates the capacity-charge revenue stream that did not exist before. Solar displaces daytime energy consumption at the (reduced) energy-component rate and, where sized appropriately, also shaves afternoon Pmax at the full capacity-charge rate. The composite solar + BESS business case gets stronger under the two-part tariff, not weaker. See Decree 58/2025/NĐ-CP for rooftop solar self-consumption framework.