Source: https://guthlabs.ai/docs/instruments/off-grid-battery-bank-sizing-solar/implementation/

instrument implementation / implementation-contract

# Off-Grid Battery Bank Sizing (Solar) implementation

A source-bound implementation contract for Off-Grid Battery Bank Sizing (Solar); deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-174

**Effect**: Computation or source lookup only

## Input and validation requirements

The formula is undefined when depth of discharge is zero, and the specification does not state required input validation. It also has no actual formula branches and leaves negative-load convention and efficiency range behavior ambiguous.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "daily_load_Wh": 3000,
    "autonomy_days": 2,
    "DoD": 0.8,
    "system_V": 48,
    "efficiency": 0.9
  },
  "expected_outputs": {
    "required_bank_Ah": 173.6111111111,
    "bank_kWh": 8.3333333333
  },
  "working": "Daily autonomy energy = 3000 Wh/day × 2 days = 6000 Wh. Denominator = 0.8 × 48 V × 0.9 = 34.56. Required Ah = 6000 ÷ 34.56 = 173.6111111111 Ah. Nominal bank energy = 173.6111111111 Ah × 48 V ÷ 1000 = 8.3333333333 kWh."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/off-grid-battery-bank-sizing-solar/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/off-grid-battery-bank-sizing-solar/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/off-grid-battery-bank-sizing-solar/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`