JEPX spot trading
The JEPX trading screen lets you submit and monitor bids on the JEPX day-ahead (spot) market for all eligible assets in the workspace. Bid volumes are taken directly from the Tensor optimization model, with the option to manually edit individual bids before submission. Bids are submitted to JEPX through our API integration, and confirmations are retrieved automatically once the auction clears.
JEPX API integration is set up per workspace by Tensor and requires a manual approval process with JEPX. Before using this screen, please contact us via the Get support button in the top navigation bar of Tensor Cloud — we will guide you through registration and verify the delivery contract code on file for your workspace.
Selecting a delivery date
Use the date picker in the top right of the screen to choose the delivery date you want to view. Bids can be submitted from up to ten days ahead, until 10:00 JST on the day before delivery — the JEPX deadline for the spot market. Past dates show the final results — clearing prices and confirmed volumes — so the same screen acts as your audit view for any prior day.
Spot tab
The Spot tab is the primary view. It lists the thirty-minute slots with bid activity for the selected delivery date, grouped by grid area.
Grid area sections
Bids on JEPX are placed per grid area, not per individual asset. When you have multiple battery assets in the same area, their per-slot charge and discharge volumes are aggregated into a single bid per slot. Each grid area appears as its own collapsible section with a status summary next to the area name:
- A count of confirmed slots — slots that cleared in full at the auction
- A count of partially confirmed slots — slots where the cleared volume is less than the submitted volume
- Not submitted — shown when no bids have been submitted for the date yet
The View history button next to each area name opens the History tab filtered to that area.
Bid table
Expanding a grid area shows one row per slot with bid activity:
| Column | Description |
|---|---|
| Slot | Thirty-minute delivery slot (for example, 09:30–10:00) |
| Direction | Sell (discharge) or Buy (charge) |
| Status | Current state of the bid — see Statuses |
| Bid volume (MW) | Volume submitted to JEPX |
| Bid price (JPY/kWh) | Limit price submitted to JEPX |
| Contract volume (MW) | Volume confirmed at the auction, once results are in |
| Market price (JPY/kWh) | Clearing price for the slot, once results are in |
| Submitter | The user who triggered the submission, or System for automated retrievals |
| Updated at | Time of the most recent change to the slot |
Slots with no bid activity do not appear in the table. Bid volumes below the JEPX minimum bid unit of 0.1 MW are excluded from submission.
Slot detail panel
Click any slot row to open a detail panel on the right. The panel shows the slot's current bid values, the submitter, and the full change history with timestamps — for example, the moment a slot moved from Submitted to Confirmed after the auction cleared. Use this panel to verify what was submitted for a specific slot, when, and by whom.
Submitting bids
By default, bid volumes are taken from the Tensor optimization model for the selected delivery date and submitted at guaranteed-execution limit prices:
- Sell bids (discharge slots): SELL-LIMIT at 0.01 JPY/kWh — the minimum price allowed on JEPX, which guarantees execution at the clearing price.
- Buy bids (charge slots): BUY-LIMIT at 200 JPY/kWh — the maximum price allowed on JEPX, which also guarantees execution at the clearing price.
Because both directions use guaranteed-execution limit prices, the effective price you trade at is always the JEPX clearing price for the slot.
When you trigger a submission, Tensor Cloud sends every slot with a non-zero bid volume to JEPX in a single batch for the selected delivery date. The status of each affected slot changes to Submitted, and once the auction clears (around 10:10 JST for next-day delivery), the platform automatically retrieves the results and moves each slot to Confirmed or Partial.
Manual overrides
If you want to deviate from the model's plan for a particular slot, you can enter or adjust the bid manually before submission. Manual entries override the model's output for the affected slot on the selected delivery date.
Resubmitting after re-optimization
If the Tensor optimization model produces a new plan after you have already submitted bids, you can resubmit at any time before the JEPX deadline. Resubmission deletes the previous bids for the delivery date on JEPX and submits the new set in a single operation. Every previous submission stays visible in the slot detail panel and on the History tab, so the full audit trail is preserved.
Statuses
A bid moves through the following states:
| Status | Meaning |
|---|---|
| Pending | Bid exists in Tensor Cloud but has not been submitted to JEPX yet |
| Submitted | Bid has been sent to JEPX and accepted into the auction |
| Confirmed | JEPX has cleared the bid in full at the auction clearing price |
| Partial | JEPX has cleared the bid for less than the submitted volume |
Direction badges next to the status indicate Sell or Buy.
History tab
The History tab lists every change that has happened to bids for the selected delivery date, in reverse chronological order. Each entry shows the slot, direction, grid area, the change itself (for example, Submitted → Confirmed, 1.5 MW @ 0.01 JPY/kWh), the actor who made the change (a user or System for automated retrievals), and when it happened.
Use the filters on the left to narrow the list:
- Slot — restrict to a single delivery slot
- Grid area — restrict to a single grid area
- Direction — sell or buy
- Change type — created, deleted, status changed, or quantity changed
The counts next to each filter option show how many changes match for the selected date. Filters combine with AND semantics — selecting Sell and Status changed, for example, returns only status changes on sell bids.