On a medium-voltage (MV) site the supply unit price is debated; the distribution tariff structure is often left as-is. Single-term prices only the kWh withdrawn. Two-term adds a power (kW) charge and lowers the kWh distribution unit. From the 4 April 2026 table, excess kW is billed at twice the capacity charge — a canned “triple penalty” slogan does not apply in this period. Which option is cheaper is read from the load profile, not from annual kWh. ENOPTIMAL’s distribution-tariff analysis runs that comparison on invoices, OSOS and `energy_tariffs` units; for an MV subscriber the year is split into three windows.
04.04.2026
In force
EMRA 14461 table
2 × GB
Demand excess
Excess kW × GAB
3 / year
MV switch right
Optimize windows
12 months
Min. data
Sound recommendation
April 2026 units: distribution, capacity, excess
ENOPTIMAL reads the April 2026+ EMRA Excel (“Tarife Tablosu” sheet); this article shows TL (kuruş records are divided by 100). Energy and distribution are TL/kWh; the capacity charge is TL/kW·month — GB is not multiplied by kWh. Even when the Excel has no separate excess column, the system writes GAB = 2 × GB. The MV rows below are the live `energy_tariffs` 2026-04-01 record (ex-VAT; August 2026 is the same).
| Subscriber group | Two-term DB (TL/kWh) | Single-term DB (TL/kWh) | GB (TL/kW·mo) | GAB (TL/kW·mo) |
|---|---|---|---|---|
| Industry | 1.0705 | 1.1825 | 35.5759 | 71.1518 |
| Commercial (public + other) | 1.6683 | 2.0811 | 89.1475 | 178.2950 |
| Residential | 1.6525 | 2.0404 | 83.7894 | 167.5788 |
| Agricultural | 1.3740 | 1.7108 | 72.7438 | 145.4877 |
| Lighting | 1.6012 | 1.9974 | 85.5762 | 171.1524 |
| Item | Calc | Amount |
|---|---|---|
| Capacity charge | 400 kW × 35.5759 TL/kW·month | 14,230.36 TL |
| Demand excess | 40 kW × 71.1518 TL/kW·month | 2,846.07 TL |
| 100,000 kWh two-term DB | 100,000 kWh × 1.0705 TL/kWh | 107,050.00 TL |
| Same kWh single-term DB | 100,000 kWh × 1.1825 TL/kWh | 118,250.00 TL |
Single-term: energy line only
Under single-term, distribution runs only on consumption (kWh). If the site withdrew little that month, no power line appears. The trade-off is the unit: industrial MV single-term DB is 1.1825 TL/kWh versus 1.0705 on two-term. That helps in low or swing months; on high, flat load the unit gap plus avoided GB stacks.
- Seasonal food, agri and tourism sites: no fixed power charge in a shut month.
- Ramp-up factory: peak kW is not settled yet; early two-term pays for empty capacity.
- Order-driven shifts: if monthly kWh swings ~40%, single-term stays flexible.
Two-term: distribution gets cheaper, GB stays every month
A two-term bill can be split three ways: kWh × two-term DB (TL/kWh) + kW × GB (TL/kW·month) + (if any) excess kW × 2×GB. The GB line can stay even if withdrawal is zero. In ENOPTIMAL’s comparison the two-term kW is the highest monthly power in the year; an “average kW” misleads.
| Swing site | Flat-load site | |
|---|---|---|
| Annual energy | 2.4 GWh | 2.4 GWh |
| Month pattern | Busy 280 MWh, quiet 80 MWh | ≈ 200 MWh ± 6% |
| Capacity factor | 30–80% | Above 70%, stable |
| Single-term effect | No GB in a quiet month; DB unit high | High DB stacks for 12 months |
| Two-term effect | GB wasted in a quiet month | Low DB + a full GB usually wins |
The real two-term risk: the wrong kW
The switch does not end with “two-term DB is cheaper”. If contract power is set low, a peak month brings GAB (2×GB); if set high, empty kW × GB is paid every month. A 40 kW start error on the industrial row is about 2,846 TL of excess — it looks small, then repeats. The right number is OSOS peak kW plus the current `energy_tariffs` row. Our kW vs kWh glossary entry summarises the unit mix-up.
- Low power: one short start combination opens a GAB line.
- Inflated power: unused kW × GB is a fixed cost for 12 months.
- Recorded as two-term, invoice still single-term: the DSO update may lag; the analysis flags that as a red row.
Why sites stay on the wrong structure
The structure picked at commissioning may have matched that year’s shift. Five years later a line is added, the season slides; the tariff stays. The supplier often talks only the energy unit. A switch is imagined as an outage risk; it is an administrative filing, power stays on. The real work is deciding without 12 months of kWh and peak kW plus current GB/GAB.
Optimize windows: three doors a year
An MV subscriber may change the tariff structure three times a year. ENOPTIMAL splits that right into three windows and recommends “switch, stay, which kW” for each. Locking the whole year to one choice leaves money on a summer-heavy / winter-quiet site. A recommendation needs at least twelve months of invoices (and OSOS if available).
| Layer | Question | Output |
|---|---|---|
| Single vs two | Which is cheaper this year? | Saving / loss per subscriber |
| Net saving | Who should actually switch? | Only the profitable sites |
| Optimize window | Which quarter to switch? | 3 windows × kW suggestion |
| Petition / report | What to file with the DSO? | Word report + petition draft |
The comparison: single-term ≈ kWh × single-term DB; two-term ≈ kWh × two-term DB + (year-max kW × GB) + excess × 2×GB. Saving = the gap (× 1.20 when VAT-inclusive). A losing subscriber does not switch. In a multi-site holding each MV subscriber is its own row.
When to look again
- A new EMRA tariff table (April / July windows) — GB and DB move; GAB stays 2×.
- A new line, furnace or cold room — peak kW moves.
- The shift pattern changed for good, or annual kWh moved more than 20%.
- OIZ internal distribution: tenant tariffs are read separately on our OIZ energy-management page.
Short questions
- Core gap: single-term is kWh×DB; two-term is kWh×DB + kW×GB + excess×2×GB.
- April 2026: GAB = 2 × GB. Source is the EMRA tariff table; the system writes the same rule.
- Single-term candidate: seasonal, low capacity factor, unsettled peak.
- Two-term candidate: three shifts, flat base load — and a peak kept under the declared kW.
- Switch: file with the DSO; timing varies by region. Simulate 12 months first.
Conclusion
MV single- vs two-term is a distribution decision, independent of supplier choice. From 4 April 2026 the excess charge is twice the capacity charge; the wrong kW inflates both GB and 2×GAB. On a swing site GB is wasted; on flat load a high single-term DB punishes you for 12 months. ENOPTIMAL calculates it subscriber by subscriber with `energy_tariffs` units and splits the year into three doors. Our industrial energy-management offer keeps consumption, invoices and tariff on one spine — if the structure is wrong, a unit discount is not enough.