Shadow-day · L4 · seller forecast-slip → IDM re-bid
IPP — wind plant (Generator) — IDM re-bid window
gen_ipp_wind_01
When a variable plant's day-ahead forecast slips beyond −5% at the IDM gate, the seller can re-bid in the intraday market rather than fall straight into the (more expensive) balancing/imbalance settlement.
Hours forecast slipped
21 / 24
Total shortfall (do nothing)
2925.4 MWh
Imbalance bill if no re-bid
R5850866.67
priced at the §07 under-delivery premium
Implied under-delivery penalty: SMP × 1.15 or an R2 000/MWh floor, whichever is higher. The floor binds when the SMP is below R1 739,13/MWh. Illustrative, basis pending NERSA (Trading Rules R2 §07 placeholder).
Re-bid window · hour 06
IDM gate timestamp: 2026-05-29T07:25:00Z
Day-ahead award 1910.0 MWh; forecast slipped -19.7% to 1533.5 MWh available — a shortfall of 376.5 MWh. Do nothing and the imbalance bill is R753000.00. There is 441.6 MWh of residual demand to re-bid into at an IDM SMP of R833.51/MWh.
24-hour forecast-slip ledger
| Hr | DAM award | Slip | Revised | Shortfall | Imbalance (do nothing) | Re-bid? |
|---|---|---|---|---|---|---|
| 00 | 1501.0 | 0.8% | 1513.3 | — | — | — |
| 01 | 1340.0 | -4.6% | 1278.2 | 61.8 | R123566.67 | — |
| 02 | 755.0 | -0.8% | 749.2 | 5.8 | R11600.00 | — |
| 03 | 1729.0 | -11.5% | 1529.5 | 199.5 | R399033.33 | eligible |
| 04 | 797.0 | -0.1% | 796.0 | 1.0 | R2066.67 | — |
| 05 | 1823.0 | -7.8% | 1681.3 | 141.7 | R283300.00 | eligible |
| 06 | 1910.0 | -19.7% | 1533.5 | 376.5 | R753000.00 | eligible |
| 07 | 1352.0 | -1.9% | 1326.2 | 25.8 | R51533.33 | — |
| 08 | 1400.0 | -13.3% | 1214.2 | 185.8 | R371633.33 | eligible |
| 09 | 1495.0 | -11.6% | 1322.2 | 172.8 | R345666.67 | eligible |
| 10 | 1290.0 | -14.9% | 1097.2 | 192.8 | R385666.67 | eligible |
| 11 | 1344.0 | -7.7% | 1240.5 | 103.5 | R207033.33 | eligible |
| 12 | 954.0 | -14.9% | 812.0 | 141.9 | R283900.00 | eligible |
| 13 | 914.0 | -18.0% | 749.6 | 164.4 | R328766.67 | eligible |
| 14 | 1505.0 | 2.7% | 1545.5 | — | — | — |
| 15 | 786.0 | -9.2% | 713.4 | 72.7 | R145300.00 | eligible |
| 16 | 1243.0 | -5.8% | 1171.3 | 71.7 | R143400.00 | eligible |
| 17 | 1514.0 | -8.9% | 1379.0 | 135.0 | R269966.67 | eligible |
| 18 | 962.0 | -17.2% | 796.5 | 165.5 | R330966.67 | eligible |
| 19 | 1225.0 | -12.9% | 1066.4 | 158.6 | R317233.33 | eligible |
| 20 | 1868.0 | -7.0% | 1737.8 | 130.2 | R260300.00 | eligible |
| 21 | 1365.0 | 0.2% | 1367.5 | — | — | — |
| 22 | 1701.0 | -12.9% | 1481.7 | 219.3 | R438533.33 | eligible |
| 23 | 1848.0 | -10.8% | 1648.8 | 199.2 | R398400.00 | eligible |