---
title: "Solar System Size Calculator (kW Needed)"
method: POST
path: "/api/v1/tools/solar-system-size-calculator"
tags: ["home"]
---

# Solar System Size Calculator (kW Needed)

`POST /api/v1/tools/solar-system-size-calculator`

## Request

- Base URL: `https://calcfleet.com`
- URL: `https://calcfleet.com/api/v1/tools/solar-system-size-calculator`
- Auth: none declared

Find the solar system size you need: enter yearly kWh usage, peak sun hours, and panel wattage to get the required kW and the number of panels it takes.

## Request body

- object
  - `annualUsageKWh` number, required
  - `peakSunHours` number, required
  - `derate` number, required
  - `panelWatts` number, required
  - `offsetFraction` number, required

## Response `200`

Successful calculation result.

- object
  - `result` object, required: Structured calculation output (fields vary per calculator).

## Other responses

- `400`: Invalid input — the issues array contains Zod validation errors.
- `403`: Forbidden — an Authorization: Bearer cf_… key was supplied but is invalid.
- `404`: Unknown tool slug.

---

[API](https://skmtc.dev/calcfleet/apis/calcfleet-financial-calculators-api.md) · [All operations](https://skmtc.dev/calcfleet/apis/calcfleet-financial-calculators-api/llms.txt) · [OpenAPI document](https://skmtc.dev/calcfleet/apis/calcfleet-financial-calculators-api/revisions/cd9abd595bbe?raw)