# Shift Input Data — Component Variable List

> **Markdown report of a non-markdown source document.**
>
> | | |
> |---|---|
> | **Source** | `Shift Matlab Drive/Shift Matlab Drive/Simulations/Shift input data.docx` |
> | **Format** | Microsoft Word (.docx) |
> | **MD5** | `b4e1cea6…` — **an identical copy** exists at `Simulations/Old Simulations/Shift input data.docx` |
> | **Author** | Robert (Simulations cluster) |
> | **Status** | Current, but **largely absorbed** by the [Simulator I/O Interface](../02-specifications/simulator-io-interface.md) |
> | **Report generated** | 2026-07-25 |

## What this document is

The first systematic enumeration of every variable each physical component needs — the raw
material from which the
[Simulator I/O Interface](../02-specifications/simulator-io-interface.md) was built. That
document cites this one directly:

> *"Set once per simulation run. These are the constants **Robert's doc** lists in bold."*
> — Simulator I/O Interface §1

It is therefore the **ancestor** of the current simulator contract, not a competitor to it.
It is kept because it records the per-component reasoning (and the alternatives considered)
that the formalised contract compressed away.

## Reading the original

The source document's structure is a single wide table whose header row explains the column
semantics. Extracted verbatim, that header reads:

> Component · Desirable Outputs — constant (if it can be found, good to compare against) ·
> Necessary Inputs — full name (unit) — Which element it applies to (less ideal alternative,
> has to be consistent throughout inputs found) · Other alternatives · Required together ·
> Output data — dynamic · Can most likely be read off the data · Unsure if it can be
> realistically acquired / if it's necessary at all *(post-processing ChatGPT assistance, thus
> it may not actually be needed)*

In practice the column-to-variable assignment does not survive extraction — the body is a flat
list per component. It is reproduced faithfully below, grouped as in the original. **Open the
original `.docx` if you need to know which column a given variable sat in.**

## Variables by component

### Electrolyser

| Symbol | Name |
|---|---|
| `N_c` | Number of cells — electrolyser |
| `P_ele` | Electrolyzer power consumption |
| `mu_F` | Faraday efficiency — electrolyser |
| `I` | Current (A) — electrolyser |
| `n_H2` | Hydrogen flow rate (mol/s) — electrolyser |
| `m_H2` | Hydrogen mass flow rate (kg/s) — electrolyser |
| `v_H2` | Hydrogen volume flow rate (L/s) — electrolyser |
| `P` | Power (W) — electrolyser |
| `V` | Voltage (V) — electrolyser |

Also listed: operating power setpoint · electrolyzer ON/OFF control signal · minimum operating
current · measured hydrogen production rate calibration factor.

### Fuel cell

| Symbol | Name |
|---|---|
| `N_c` | Number of cells — fuel cell |
| `I` | Current (A) — fuel cell |
| `Utilisation` | Percentage (%) — fuel cell |
| `n_H2_in` | Hydrogen flow rate into the fuel cell (mol) |
| `n_H2_used` | Hydrogen flow rate consumed by the fuel cell (mol) |
| `P` | Power (W) — fuel cell |
| `V` | Voltage (V) — fuel cell |

Also listed: fuel cell operating voltage range · maximum fuel cell output power · fuel cell
ON/OFF control signal.

### Hydrogen tank

| Symbol | Name |
|---|---|
| `V_H2` | Volume of hydrogen stored (L) + maximum + initial |
| `T` | Temperature (K) |
| `p` | Atmospheric pressure (atm) |
| `n_H2_in` | Hydrogen flow rate into the tank (mol) |
| `n_H2_used` | Hydrogen flow rate output by tank (mol) |

### PV

| Symbol | Name |
|---|---|
| `mu` | Panel efficiency |
| `P_PV` | Solar panel power |
| — | Irradiance (W/m²) — PV throughout the day |
| `A_PV` | Area of the solar cell |
| `I` | Current (A) — PV |
| `P` | Power (W) — PV |
| `V` | Voltage (V) — PV |

### Battery

| Symbol | Name |
|---|---|
| — | Maximum charge/discharge power |
| `SoC` | State of charge + maximum + initial |
| `E_rated` | Rated voltage |
| `Q_rated` | Rated charge capacity |
| `I` | Current (A) — battery |
| `P` | Power (W) — battery |
| `V` | Voltage (V) — battery |

> [!WARNING]
> `E_rated` is glossed here as **"rated voltage"**. In the
> [Simulator I/O Interface §1.5](../02-specifications/simulator-io-interface.md#15-battery) and
> in [`Constants.mlx`](matlab-live-scripts.md) it is **rated energy capacity in Wh**. The
> later definition is the one in use; this line is an early slip.

### Load (hospital / wards / rooms)

| Symbol | Name |
|---|---|
| `P` | Power (W) |
| `V` | Voltage (V) |
| `I` | Current (A) |

### External power (grid / microgrid)

| Symbol | Name |
|---|---|
| `P` | Power (W) + import/export |
| `V` | Voltage (V) |
| `I` | Current (A) |
| — | Grid availability (ON/OFF) |
| — | Maximum grid connection capacity |

## What changed on the way to the simulator contract

| This document | Simulator I/O Interface | Note |
|---|---|---|
| `N_c`, `mu_F`, `I` per component | `N_c_ele` / `N_c_fc`, `mu_F`, `I_ele_min` | Namespaced per component to remove collisions |
| `V_H2` in L | `V_H2_max` in **L or kg**; `H2_level(t)` in **mol or kg** | Unit still unresolved — flagged TBD there |
| `E_rated` = rated voltage | `E_rated` = rated energy capacity (Wh) | Corrected |
| Per-component `V` and `I` everywhere | Dropped; only `V_load`, `V_grid`, `V_fc_min/max` survive | The simulator is a power-flow model, not a circuit model |
| Operating setpoints listed inline | Split into a distinct §2.2 control-input block (`u_ele`, `u_fc`, `u_batt`, `sw_*`) | Setpoints separated from measurements |
| — | Sign conventions, power-balance invariant, priority rules, KPI block | New — these are the genuinely additive parts |

The one thing this document has that the successor lacks is the **per-component electrical
detail** (`V` and `I` for every element). If the project ever moves from power-flow to circuit
simulation — for example to use the PowerWorld model — this list is the starting point.

## Duplicate copy

An identical file (same MD5) sits at
`Shift Matlab Drive/Shift Matlab Drive/Simulations/Old Simulations/Shift input data.docx`. The
copy in `Old Simulations/` is retired to [`superseded/`](../../superseded/); the one in
`Simulations/` remains.

## Related

- [Simulator I/O Interface](../02-specifications/simulator-io-interface.md) — the formalised successor
- [MATLAB Live Scripts](matlab-live-scripts.md) — `Constants.mlx` implements a subset of these
- [PV + Battery Simulink Model](pv-battery-simulink.md)
- [BIDMC Digital Twin Readiness Checklist](../03-energy-management/bidmc-digital-twin-readiness-checklist.md) — repeatedly refers to "Shift data" meaning this variable set