Crate grid_billing 

Role-neutral German grid settlement calculation engine.

Covers all DSO/TSO-side INVOIC documents:

• NNE (Netznutzungsentgelt) — PID 31002 (NN-Rechnung, Strom + Gas); Abschlag 31001
• MMM (Mehr-/Mindermengensaldo) — PIDs 31005/31006 (aggregiert Gas 31007/31008)
• MSB (Messstellenbetrieb) — PID 31009

Calculation flow

Input → validation → Settlement Engine → SettlementResult → into_rechnung() (service layer)

SettlementResult is the canonical output. The service layer (netzbilanzd, invoicd) converts it to BO4E Rechnung. This keeps grid-billing publishable to crates.io without pulling in the internal rubo4e crate.

Explainability

Every SettlementPosition carries a CalculationTrace with:

• input values (quantity, unit price)
• gross intermediate result before rounding
• applicable LegalReferences (e.g. StromNEV §17, KAV §2)
• the TariffSource justifying each rate

No float money

Quantities, rates, and factors are rust_decimal::Decimal; every EUR result is range-checked through the billing::EuroAmount newtype (Amount<5>) before it leaves the crate.

Example

use grid_billing::{
    ArbeitspreisModell, InvoiceDocument, KaKundengruppe, Konzessionsabgabe, MengePreis,
    NneInput, SettlementPeriod, settle_nne,
};
use rust_decimal::Decimal;
use time::macros::date;

fn d(s: &str) -> Decimal { Decimal::from_str_exact(s).unwrap() }

// The engine is given what was supplied and at what rates — no invoice
// number, no issue date, no Prüfidentifikator.
let settlement = settle_nne(&NneInput {
    malo_id: "51238696780".into(),
    nb_mp_id: "9900357000004".into(),
    lf_mp_id: "9900012345678".into(),
    period: SettlementPeriod::new(date!(2025-01-01), date!(2025-01-31))?,
    // One value, not twelve loose fields: flat rate, §14a Modul 1, Modul 2
    // HT/NT and Modul 3 are mutually exclusive by construction.
    arbeitspreis: ArbeitspreisModell::Einheitlich(MengePreis {
        menge_kwh: d("1500"),
        preis_ct_per_kwh: d("3.5"),
    }),
    leistungspreis: None,
    letztverbrauchergruppe: Default::default(),
    sect19_umlage_ct_per_kwh: None,
    offshore_umlage_ct_per_kwh: None,
    kwkg_umlage_ct_per_kwh: None,
    grundpreis: None,
    // Recorded so an auditor can check the rate came from the right sheet.
    netzebene: Some(grid_billing::netzebene::Netzebene::Niederspannung),
    sect19: None,
    gas_kapazitaet: None,
    jahreshoechstleistung_kw: None,
    jahresarbeit_kwh: Some(d("18000")),
    // Rate and customer group travel together, so the KAV §2 Höchstbetrag is
    // always checked.
    konzessionsabgabe: Some(Konzessionsabgabe {
        satz_ct_per_kwh: d("0.11"),
        klasse: KaKundengruppe::Sondervertragskunde,
    }),
    tariff_sheet_id: Some("Preisblatt-NNE-2025-Q1".into()),
    sparte: grid_billing::Sparte::Strom,
})?;

// Every position explains itself:
for pos in &settlement.positions {
    println!("{}: {}", pos.text, pos.trace.explanation);
}
for r in settlement.all_legal_refs() {
    println!("  → {r}");
}

// Presenting it as an invoice is a separate step, and the only place
// document identity enters.
let document = InvoiceDocument {
    settlement,
    pid: 31002,
    rechnungsnummer: "NNE-2025-001".into(),
    correction_of: None,
    invoice_date: date!(2025-02-15),
    due_date: date!(2025-03-15),
};
for (number, pos) in document.numbered_positions() {
    println!("{number}. {}", pos.text);
}

Re-exports

pub use billing::correct;

pub use billing::reverse;

pub use billing::settle_gas_awh;

pub use billing::settle_mmm;

pub use billing::settle_msb;

pub use billing::settle_nne;

pub use error::BillingError;

pub use redispatch::RedispatchVerguetung;

pub use redispatch::RedispatchVerguetungInput;

pub use redispatch::RedispatchVerguetungsart;

pub use redispatch::bilarem_finanzielle_korrektur;

pub use redispatch::eeg_entgangene_einnahmen;

pub use redispatch::redispatch_verguetung;

pub use regulatory::EntgeltRegime;

pub use regulatory::NetzzugangRegime;

pub use regulatory::RegulatoryRegime;

pub use regulatory::SECT19_ABS3_LETZTER_TAG;

pub use regulatory::SECT19_ABS3_UEBERGANG_ENDE;

pub use types::ArbeitspreisModell;

pub use types::AwhPositionInput;

pub use types::BillingPositionKind;

pub use types::CalculationTrace;

pub use types::GasAwhInput;

pub use types::GemeindeGroesse;

pub use types::Grundpreis;

pub use types::InvoiceDocument;

pub use types::KaKundengruppe;

pub use types::Konzessionsabgabe;

pub use types::LegalReference;

pub use types::Leistungspreis;

pub use types::MengePreis;

pub use types::MmmInput;

pub use types::MsbInput;

pub use types::NneInput;

pub use types::PriceReference;

pub use types::PriceStep;

pub use types::QuantityUnit;

pub use types::Reduktionsfaktor;

pub use types::Sect14aModul3Interval;

pub use types::Sect14aModule;

pub use types::SettlementPeriod;

pub use types::SettlementPosition;

pub use types::SettlementResult;

pub use types::SettlementStatus;

pub use types::SettlementType;

pub use types::SettlementWarning;

pub use types::Sparte;

pub use types::SpotPriceFormula;

pub use types::TariffCalculationMethod;

pub use types::TariffSource;

pub use types::ValidationResult;

pub use types::WarningSeverity;

pub use types::validate_gas_awh_input;

pub use types::validate_mmm_input;

pub use types::validate_msb_input;

Modules

billing

NNE, MMM, and MSB settlement calculation logic.

error

Error types for grid-billing.

gas

Gas network structure — Druckstufen and Kapazitätsprodukte, §15 GasNEV.

msbg

Preisobergrenzen für den Messstellenbetrieb — §30 MsbG.

netzebene

Netzebenen und Entgeltsystematik — §17 StromNEV.

redispatch

§13a EnWG Redispatch 2.0 compensation (angemessene Vergütung).

regulatory

Which rules were in force for a delivery period.

sect18

Entgelte für dezentrale Erzeugung — §18 StromNEV, under Abschmelzung.

sect19

Individuelle Netzentgelte — §19 Abs. 2 StromNEV.

types

Input/output types for the settlement calculation engine.

umlagen

Netzseitige Umlagen — the levies the ÜNB collect through the Netzentgelt.