Source: https://guthlabs.ai/docs/instruments/solar-charge-controller-sizing-pwm-mppt/implementation/

instrument implementation / implementation-contract

# Solar Charge Controller Sizing (PWM/MPPT) implementation

A source-bound implementation contract for Solar Charge Controller Sizing (PWM/MPPT); 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**: t4-162

**Effect**: Computation or source lookup only

## Input and validation requirements

An extreme but numerically valid Isc input produces Infinity in JavaScript arithmetic, and a negative signed Isc can produce an invalid negative required rating unless the instrument explicitly applies a magnitude convention. Exact voltage equality also correctly fails because the specified comparison is strict.

## 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": {
    "array_Isc_A": 10.8,
    "cold_corrected_string_Voc_V": 41.2,
    "controller_max_input_voltage_V": 60
  },
  "expected_outputs": {
    "required_controller_current_A": 13.5,
    "maximum_voltage_check": "PASS"
  },
  "working": "Required current = Isc × 1.25 = 10.8 A × 1.25 = 10.8 A + (10.8 A × 0.25) = 10.8 A + 2.7 A = 13.5 A. Voltage check: 41.2 V < 60 V, so PASS."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/solar-charge-controller-sizing-pwm-mppt/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/solar-charge-controller-sizing-pwm-mppt/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/solar-charge-controller-sizing-pwm-mppt/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`