# Source Member > Supply offers over a forward vector, committed take, forecast-error open items, v26.0 single-class supply, and Grid 1 interconnection fallback. - Repository: g2tf-org/g2tf-standards - GitHub: https://github.com/g2tf-org/g2tf-standards - Human docs: https://grok-wiki.com/public/docs/g2tf-org-g2tf-standards-436ba3f3e0ff - Complete Markdown: https://grok-wiki.com/public/docs/g2tf-org-g2tf-standards-436ba3f3e0ff/llms-full.txt ## Source Files - `members/source.md` - `specs/g2p/spec.md` - `specs/gcap/spec.md` - `architecture/failsafe-model.md` - `architecture/overview.md` --- --- title: "Source Member" description: "Supply offers over a forward vector, committed take, forecast-error open items, v26.0 single-class supply, and Grid 1 interconnection fallback." --- A **Source Member** is the Member Element for clean-energy / inverter-based supply (solar, wind). The living contract is `members/source.md` (Draft — seeking input; RFC #1 Protocol Interactions table). Each interval it publishes a signed G2P **Service Descriptor** *offer to supply* (`−`) over a forward time vector, listens for the Allocator's **committed take**, self-dispatches to that take within host-utility ramp rates, and reports verified self-dispatch. v26.0 carries a single supply class. On a missing or stale Commitment it MUST revert to Grid 1 baseline interconnection behavior. Living files `members/source.md`, `specs/g2p/spec.md` (26.0-draft), and `specs/gcap/spec.md` (26.0-draft) are **Draft — seeking input**. RFC 2119 / RFC 8174 keywords apply. Wire format, element state machines, and conformance vectors are unspecified (G2P §7). ## Role Source is one of three Member Element kinds on the Grid 2 overlay (Use, Buffer, Source). It is a digital representative of a physical point of interconnection, not a market participant or price-setting agent. | Field | Value | |---|---| | Associated asset | Clean-energy / inverter-based supply — solar, wind | | Ledger sign | *Offer to supply* (`−`) | | Listen surface | Allocator **committed take** (not Use **commit-%**, not Buffer **committed dispatch**) | | Edge intelligence | Forecast available output; anticipate ramps | | v26.0 energy unit | Energy provided in the one-minute interval | | Failsafe | Grid 1 baseline interconnection behavior; allowed ramp rates | | Document status | Draft — seeking input · Editors TBD | The same G2P/GCAP stack that clears load-side positions also bounds Grid 2-compliant supply. RFC #1 and `members/source.md` treat that as the interconnection-side counterpart of load flex: permission-based access each interval instead of a one-shot interconnection permit. A companion G2TF document on expedited renewables interconnection is planned; it is not a living spec in this repository. The smallest Allocation Domain is a host utility plus one flexible **Use** Member. A Source is not required to stand up a domain. Federation diagrams place some Sources at the regional layer (`Supply (Source Member, regional)`), not only under a local utility domain. ## Interval contract Every Source MUST hold a stable element identifier bound to a physical point of interconnection in a provisioned Allocation Domain. Identifier format is open (G2P §2). All messages bind to the one-minute interval clock. Allocations apply to the coming interval only and expire with it. Grid 2 MUST NOT interfere with sub-second Grid 1 primary controls. Where a Grid 1 dispatch instruction conflicts with a Grid 2 allocation, **the Grid 1 instruction prevails**. ```mermaid sequenceDiagram participant Src as Source Member participant Alloc as Allocator participant G1 as Grid 1 interconnection Note over Src,Alloc: Interval n (one minute) Src->>Alloc: Service Descriptor: offer to supply (−)
signed, energy in interval, forward vector Note over Alloc: GCAP deterministic clear
headroom → Buffers → C then B then A Alloc-->>Src: Commitment: committed take
interval, domain, inputs version alt Commitment fresh Src->>G1: Self-dispatch to committed take
within agreed ramp rates Src->>Alloc: Response / telemetry
verified self-dispatch (G2P §3.4) else Missing, stale, or Allocator withheld Src->>G1: Fallback: Grid 1 baseline interconnection
allowed ramp rates end ``` Sign an *offer to supply* (`−`) for generation available this window, over a forward time vector. Positions MUST be in units of energy within the interval. Reissue MAY happen each interval. Listen only for this Source's Allocator Commitment. Treat a missing or stale Commitment as fallback-triggering. Do not infer take from a peer, a federation announcement, or a prior interval. G2P requires clearing to complete so Members receive the Commitment with time to self-dispatch before the interval opens. Intra-interval deadlines (descriptor, clear, publish) are open. Report actual dispatch against the Commitment. If the Allocator withheld (stale constraint inputs or partition) or the Commitment did not arrive, revert to Grid 1 interconnection behavior on the agreed ramp. ## Broadcast: offer to supply G2P §3.1 Service Descriptor (Member → Allocator) is the Source's outbound surface. A Source does **not** publish per-class consume positions and does **not** flip sign the way a Buffer does (`−` discharge / `+` charge). Bound to the physical point of interconnection in the provisioned Allocation Domain. Format open. Generation available this window. MUST be signed by the originating Member. MUST be energy in the interval (v26.0). Single class in v26.0 — not DESP A/B/C. Offer is over a forward time vector. Length, resolution, and revision rules are open (G2P §3.1). G2P does not specify a wire encoding. Do not treat the field names above as a schema. Implementations must still satisfy the signed-descriptor, energy-unit, authentication, and interval-binding MUSTS. Authentication: every Service Descriptor MUST be authenticated; integrity MUST be verifiable end-to-end. Transmission-level deployments are expected on private networks. PKI, NERC CIP mapping, and replay protection remain open (G2P §6). ## Listen: committed take G2P §3.2 / GCAP §4 emit **committed take** to each Source. That is distinct from the other two Member listen surfaces. | Member | Commitment field | When it clears | |---|---|---| | Use | Per-class **commit-%** | After headroom and Buffer dispatch; C then B then A if still short | | Buffer | **Committed dispatch** | GCAP step 2 — **before any load is curtailed** | | Source | **Committed take** | Per-interval output of the same clear; supply class order is not specified | Quantity the Source MUST self-dispatch toward. Allocator has no discretion: identical inputs MUST produce identical allocations. Commitments MUST identify the interval they apply to. Valid for that interval only. Commitments MUST identify the domain. Commitments MUST identify the clearing inputs version they were computed against. Allocators SHOULD publish the input digest in-domain. A Member that has not received a Commitment for the current interval MUST treat itself as in fallback. Quantitative staleness timers (missed intervals before fallback) are still to be specified in G2P. ## Edge intelligence The Allocator holds **no internal intelligence**. Forecast and ramp anticipation live on the Source: - Forecast available output for the forward vector. - Anticipate ramps so consecutive-interval deltas stay inside the host-utility agreed rates. GCAP still binds **per-member allocation deltas** between consecutive intervals to those agreed ramp rates. Pool-level: the Allocator MUST bound total cleared participation so simultaneous member fallback stays inside manageable aggregate Grid 1 ramp limits. Forecast accuracy expectations, and how forecast error interacts with GCAP **headroom**, are open items on `members/source.md`. Do not assume an offer-to-supply automatically increases domain headroom, or that under-delivery is absorbed by a specified GCAP term. Grid 1 ancillaries absorb interval error without modification; NERC CPS1/BAL remain the balancing measures. ## Obligations | Requirement | Normative text | |---|---| | Self-dispatch | MUST self-dispatch to committed take within agreed ramp rates | | Telemetry | MUST report verified self-dispatch (G2P §3.4) | | Ramp on every transition | MUST follow allowed ramp rates into fallback, out of fallback, and between interval allocations | | Local fallback | Fallback MUST be locally determinable from the Member's own state and last-known configuration; MUST NOT depend on reaching a remote peer | | Grid 1 prevails | If a Grid 1 dispatch instruction conflicts with the Grid 2 take, follow Grid 1 | | Overlay duties | Continue to meet all NERC, FERC, utility, and TSO/ISO requirements in the Grid 1 context | G2P §3.4 states Members MUST report **actual per-class dispatch** against the Commitment. For a v26.0 Source that is the single supply position. Verification granularity, metering source of truth, and attestation are open. Commercial terms (interconnection product, charging, class-policy limits if supply classes appear later) stay in the domain agreement, not in G2P/GCAP/DESP. ## v26.0 single-class supply DESP A / B / C stratify **demand** above traditional Grid 1 Firm. Use Service Descriptors carry one signed consume position per class. Source does not. `members/source.md` records the open question explicitly: class structure for supply offers is **single class in v26.0**, or mirrored A/B/C later. Until that is closed: - Do not emit Assured / Preferred / Best-Efforts (or Firm / Semi-Firm / Flex) positions on a Source Descriptor. - Do not expect GCAP's C → B → A curtailment order to rank supply offers. - Domain class-policy limits in DESP §4 (for example a minimum Class C share for expedited interconnection) apply to declared demand classes, not to a specified Source class table. ## Failsafe | Trigger | Source behavior | |---|---| | Loss of Allocator, peers, or fresh context | MUST revert to Grid 1 baseline interconnection behavior; MUST follow allowed ramp rates | | Missing or stale Commitment | Same fallback (G2P §3.2, failsafe model) | | Allocator stale inputs or partition | Allocator MUST NOT clear; Source falls back as above | | Federation partition elsewhere | MUST NOT trip this Source if its local Allocator still clears | Fallback carries no extra Grid 2 support duty (contrast Buffer: no Grid 2 support commitment while in fallback). Re-entry procedure and hysteresis after fallback are open. ```text last Commitment for this interval? │ yes │ no / stale / withheld ▼ self-dispatch to Grid 1 baseline committed take interconnection (agreed ramp) (agreed ramp) ``` ## Open items that bind implementers Treat these as unspecified, not as implied product behavior: | Item | Why it matters on the Source | |---|---| | Forecast accuracy vs GCAP headroom | No specified penalty, reserve, or headroom adjustment for forecast error | | Curtailed Source energy → co-located Buffer same interval | Not allowed by a specified message; do not invent an intra-interval redirect | | Supply class structure after v26.0 | Single-class now; A/B/C mirror is a live question | | Forward-vector length / revision | Cannot yet size descriptor history or mid-horizon edits | | Intra-interval timing budget | Descriptor deadline, clear deadline, commit publish, clock sync | | Staleness threshold | How many missed intervals before fallback | | Telemetry / attestation | What "verified self-dispatch" must prove | | Wire format | No encoding, version negotiation, or test vectors yet | Comment via GitHub Discussions (Engineering / Reliability assurance) or a PR against `members/source.md` and the three specs. Errata against RFC #1 use the `errata` label. ## Phase 0 Phase 0 shadow mode exchanges and tracks Commitments but **executes only the Grid 1 baseline**. A Source implementation in Phase 0 still publishes descriptors and records committed take; it MUST NOT change physical output from its Grid 1 interconnection schedule until Phase 1 local integration. ## Next Per-class consume positions and commit-% — the demand-side counterpart of committed take. Signed charge/discharge offers and committed dispatch before any load curtailment. Deterministic GCAP clear that emits committed take; withhold-on-stale; pool ramp sizing. Service Descriptor, Commitment, telemetry, authentication, and unspecified wire format. Headroom, then Buffers, then C-B-A; interval-only outputs; identical-input determinism. Grid 1 interconnection fallback, interval-only commitments, locally determinable recovery. Exchange commitments, execute Grid 1 only, then Phase 1 / Phase 2.