Balancing Sums

Every day, for the day before, the transmission system operator (TSO) sends the balance responsible party (BRP) the Bilanzkreissummenzeitreihen of Kategorie C (BK-SZR, MaBiS code ZA0). There is one per control area and Zeitreihentyp. Each covers the market locations whose aggregation the TSO carries for our balancing group: smart meters (iMS) balanced on quarter-hour values, once their network operator has handed the aggregation to the TSO. The TSO activates the series when the first such market location is assigned to the balancing group, and sends it every calendar day for the previous day by 13:00, weekends and holidays included. The series is informational: MaBiS does not use it in settlement, which runs on the monthly Kategorie A/B series. It is the earliest view of what the smart-meter part of the portfolio actually consumed or fed in. That makes it the input for checking the forecast of those customers. GET /v1/sum-time-series/category-c?date_from=YYYY-MM-DD[&date_to=YYYY-MM-DD] Use the same key as for POST /v1/forecasts.

curl "$NLEAD_BASE_URL/v1/sum-time-series/category-c?date_from=2026-10-01&date_to=2026-10-07" \
  --header "X-API-Key: $NLEAD_API_KEY"

Parameter	Meaning
`date_from`	First delivery day (German calendar day); at most 180 days back — a `422` names the earliest day
`date_to`	Last delivery day, inclusive. Defaults to `date_from`; at most 31 days per call and at most 31 days ahead of today

The answer has one entry per delivery day, and per day one entry per series. In the example below, values and statuses are cut to four of the 96 entries.

Field	Meaning
`control_area` / `control_area_eic`	The control area the TSO formed the sum for
`balancing_group_eic`	The balancing group; `sub_balancing_group` names a sub-balancing group (e.g. `CLOOVER_GRUEN`), `null` for the main one
`series_type`	Zeitreihentyp: `LGS` measured consumption, `EGS` measured feed-in, …
`metering_point`	The MaBiS metering point (Zählpunkt) of the series
`sender_mp_id`	Who sends it: the TSO
`unit`	`kWh` — energy per quarter hour, not average power
`values`	One value per quarter hour of the German day (96, 92 or 100), in order; `null` where nothing has arrived yet
`statuses`	The MSCONS qualifier of each value: `220` true value, `67` substitute value, `Z18` provisional, `Z30` missing — the TSO formed the sum with values missing, so it is a lower bound
`complete`	Every quarter hour has a value and none is marked `Z30`
`total`	Sum of the received values, `Z30` quarter hours included
`quality_codes`	The distinct qualifiers in `statuses`
`received_at` / `message_references`	When the latest message for the day arrived, and the messages behind it

{
  "category": "C",
  "date_from": "2026-10-13",
  "date_to": "2026-10-13",
  "days": [
    {
      "delivery_day": "2026-10-13",
      "interval_count": 96,
      "series": [
        {
          "control_area": "TenneT",
          "control_area_eic": "10YDE-EON------1",
          "balancing_group_eic": "11X0-0000-0929-3",
          "sub_balancing_group": null,
          "series_type": "LGS",
          "metering_point": "4033872000058BKA00000067718950TLG",
          "sender_mp_id": "4033872000058",
          "obis": "1-1:1.29.0",
          "unit": "kWh",
          "values": [0.0, 0.0, 0.0, 0.0],
          "statuses": ["220", "220", "220", "220"],
          "received_intervals": 96,
          "complete": true,
          "total": 0.0,
          "quality_codes": ["220"],
          "received_at": "2026-10-14T12:37:00+02:00",
          "message_references": ["TB184815634A"]
        }
      ]
    }
  ]
}

Things to know:

Listed before it arrives. A series appears for every day its metering point is activated, whether or not values have arrived. Until the TSO sends the day, values holds null and complete is false. After a deactivation it is listed only on days for which the TSO still sends values; if it is activated again, it is listed again from the new start.
Corrections replace. If the TSO sends a quarter hour again, the later value replaces the earlier one, and received_at moves with it.
Only part of the portfolio. The series covers only the market locations the TSO aggregates. It does not cover customers on standard load profiles (SLP/TLP), customers with conventional meters, or smart-meter customers whose aggregation is still with the network operator. Compare it only with the forecast share of the customers it covers. A whole-portfolio forecast would show a standing gap that is not forecast error.
Converting to your forecast’s unit. The values are energy per quarter hour in unit, normally kWh. If your forecast is in MW (average power), divide the kWh by 250 (÷1000 to MWh, ×4 for the quarter hour). If it is in MWH (energy per quarter hour), divide by 1000.
History. The bridge reads the messages of the last 180 days. A date_from before that is refused with 422, naming the earliest day available; the messages are listed on the troubleshooting page.
Read-only. Calling the endpoint sends nothing to the market. A sandbox key works the same way.

Getting Started

Delivering Data

Background