---
title: "Callisto II Energy Center"
description: "Callisto II Energy Center: 203 MW Battery project in Harris County, ERCOT HOUSTON developed by Callisto II Energy Center LLC. Currently IA + FIS complete; build-chance 69%. Independent ERCOT queue tracking by Matt Prusak."
canonical: "https://www.ercotqueue.com/project/22INR0558"
markdown: "https://www.ercotqueue.com/project/22INR0558.md"
resource_type: "project"
source_report: "August 2026"
generated_at: "2026-09-08T19:34:08.442Z"
license: "https://creativecommons.org/licenses/by/4.0/"
---

# Callisto II Energy Center

Callisto II Energy Center is an ERCOT generation interconnection record identified by INR 22INR0558.

## Current reported project fields

| Field | Value |
| --- | --- |
| INR | 22INR0558 |
| Developer | [Callisto II Energy Center LLC](https://www.ercotqueue.com/developer/callisto-ii-energy-center-llc.md) |
| Fuel / technology | Battery / BA |
| Capacity | 203.2 MW |
| County | Harris County |
| ERCOT zone | HOUSTON |
| Point of interconnection | 47150 HO Clarke 138kV |
| Projected commercial-operation date | 2026-10-01 |
| Reported status | SS Completed, FIS Completed, IA |
| Funnel stage | Interconnection agreement and FIS complete |

County is the public geographic precision used by ERCOTQueue. Map symbols are county-level evidence and are not exact project coordinates.

## Independently derived Build Chance

| Measure | Value |
| --- | ---: |
| Validation-selected Build Chance | 69% |
| P05 | 63% |
| P50 | 68% |
| P95 | 72% |

### Score factors

| Factor | Percentage-point contribution |
| --- | ---: |
| Stage base rate | +91.5 pp |
| Fuel adjustment | -2.9 pp |
| Developer-history adjustment | 0.0 pp |
| Stage-velocity adjustment | -10.0 pp |
| COD-slippage adjustment | -10.0 pp |
| FIS-progress adjustment | 0.0 pp |
| Capacity adjustment | +0.1 pp |

These factors are ERCOTQueue derivations. The displayed probability is not an ERCOT forecast or an official project status.

## Reported milestones

| Milestone | Date |
| --- | --- |
| screening started | 2021-10-07 |
| screening complete | 2021-12-08 |
| fis requested | 2021-09-29 |
| fis approved | 2025-08-21 |
| ia signed | 2023-12-11 |

## Observed monthly history

- First seen: 2021-10
- Last seen: 2026-08
- Appearances: 59
- Score-series basis: Monthly points use the as-of seven-factor raw model on the validation-selected raw scale because the current isotonic candidate did not pass the project-purged application guard. The final point is anchored to the published current project score. The series shows trajectory, not a previously published frozen forecast.

The 30 most recent observed changes are shown below. The public JSON contains the complete history.

| Report month | Change | Detail |
| --- | --- | --- |
| 2026-05 | Projected COD | 2026-07-20 to 2026-10-01 (+3 months) |
| 2026-01 | Projected COD | 2026-07-01 to 2026-07-20 (0 months) |
| 2025-08 | Funnel stage | IA signed, FIS pending to IA + FIS complete |
| 2025-01 | Projected COD | 2025-12-10 to 2026-07-01 (+7 months) |
| 2023-12 | Funnel stage | No IA to IA signed, FIS pending |
| 2023-08 | Developer field | Saracen III Energy Storage LLC to Callisto II Energy Center LLC |
| 2023-07 | Projected COD | 2024-06-01 to 2025-12-10 (+18 months) |
| 2022-10 | Projected COD | 2023-12-01 to 2024-06-01 (+6 months) |
| 2021-11 | Projected COD | 2022-12-01 to 2023-12-01 (+12 months) |
| 2021-10 | Funnel stage | First observation to No IA |

Complete project-history JSON: [https://www.ercotqueue.com/data/project_history/22INR0558.json](https://www.ercotqueue.com/data/project_history/22INR0558.json)

## Field provenance

- Reported fields: INR, name, developer, capacity, fuel, county, zone, point of interconnection, projected COD, status, and dated milestones.
- Derived fields: funnel stage, COD-delay indicators, Build Chance, factor contributions, and uncertainty range.
- Current project dataset: [https://www.ercotqueue.com/data/projects.json](https://www.ercotqueue.com/data/projects.json)
- Current flat CSV: [https://www.ercotqueue.com/data/projects.csv](https://www.ercotqueue.com/data/projects.csv)

## Source, citation, and reuse

- Human-readable page: [Callisto II Energy Center](https://www.ercotqueue.com/project/22INR0558)
- Markdown representation: [https://www.ercotqueue.com/project/22INR0558.md](https://www.ercotqueue.com/project/22INR0558.md)
- Source report: August 2026
- Site refresh: September 2026
- Methodology: [ERCOTQueue methodology](https://www.ercotqueue.com/methodology)
- License: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/)
- Source data (application/json): [https://www.ercotqueue.com/data/projects.json](https://www.ercotqueue.com/data/projects.json)

ERCOTQueue distinguishes reported source fields from independently derived analysis. Queue capacity records development and interconnection activity; it does not establish financing, construction, or commercial operation. Build Chance is a research signal, not a guarantee or investment recommendation.