Phase 1 shadow · synthetic · independent  ·  SAWEM Phase 1 Trading Simulator — explainer-grade, not an MMS.  ·  Built from the publicly available Trading Rules; Round 2 not yet gazetted
Trading day 2026-05-29 virtual hour 00 Auction state: ACCEPTING gate close in 18h:00m DAM clear IDM re-clear Balancing Settlement
SAWEM
Day-ahead clearing

Hour 21 · 2026-05-29

Illustrative clearing — production MMS would use a SCED-class optimiser.

demand side · Phase 1 This hour clears against an exogenous system-load forecast (the dashed green demand line below), not a buyer bid-stack vs supply-stack intersection. Buyer bids are price-taking (illustrative) in Phase 1: they fix each buyer's scheduled volume but do not set the SMP. Bid-driven demand clearing is on the roadmap.

Why this price?

In hour 21, the SMP cleared at R864.37 / MWh. The marginal offer was Eskom Holdings — coal fleet (Generator)'s — the last unit of generation needed to meet demand. By uniform-price rule, every accepted seller was paid R864.37 / MWh for their share of the 26000 MWh cleared this hour.

See the in-browser verifier to confirm the SMP from the receipt's canonical inputs.

SMP
R864.37 / MWh
Total dispatch
26,000 MWh
Marginal party
Eskom Holdings — coal fleet (Generator)
gen_eskom_coal_01

Supply curve · demand intersection

Aggregator — renewables pool — R382/MWh up to 3000 MWhIPP — wind plant (Generator) — R464/MWh up to 4365 MWhEskom Holdings — coal fleet (Generator) — R864/MWh up to 34365 MWhIPP — battery storage (BESS) (Generator) — R1083/MWh up to 38365 MWhIPP — gas CCGT (Generator) — R1137/MWh up to 44365 MWhEskom Holdings — OCGT peaker (Generator) — R2200/MWh up to 48865 MWhEmergency reserve — synthetic scarcity tier (Generator) — R4507/MWh up to 62865 MWhDemand 26000 MWhSMP R864/MWh

The supply curve (terracotta) is cumulative MWh on the x-axis, offer price on the y-axis. The dashed green line is hourly demand. Where they cross is the SMP.

Accepted awards

Offer Party MWh awarded Price (R/MWh)
o-21-renew-agg Aggregator — renewables pool 3000.0 R864.37
o-21-wind IPP — wind plant (Generator) 1365.0 R864.37
o-21-coal Eskom Holdings — coal fleet (Generator) 21635.0 R864.37
Show full computation transcript
[clearHour] day=2026-05-29 hour=21 seed=42
[clearHour] tieBreak=price_asc → ts_asc → party_id_asc
[clearHour] demand_mw_min=1560000
[clearHour] accept offer=o-21-renew-agg party=agg_renewables_01 price=38214c volume=180000 cumulative=180000
[clearHour] accept offer=o-21-wind party=gen_ipp_wind_01 price=46372c volume=81900 cumulative=261900
[clearHour] accept offer=o-21-coal party=gen_eskom_coal_01 price=86437c volume=1298100 cumulative=1560000
[clearHour] SMP=86437c marginal=gen_eskom_coal_01

Verify from your laptop (terminal): curl -s /api/clearing/21/replay > receipt.json && npm run verify -- receipt.json

Or in your browser (no install): /clearing/21/verify

Download replay bundle (.json)

Audit chain · stage 1 of 4

Commit this DAM clear to the append-only SHA-256 chain (dam_cleared event). Best-effort: with no D1 binding bound locally this degrades to a "not recorded" marker rather than failing.

Data as-of: 2026-05-29 · Trading Rules R2 v01 (2026-04-12 draft) · Market Code v2.1 · simulator build 2026-05-29.