# Home battery sizing calculator

- Human page: https://happytails.ai/en/calculators/home-battery-sizing-calculator/
- Markdown: https://happytails.ai/en/calculators/home-battery-sizing-calculator.md
- Structured JSON: https://happytails.ai/agents/en/calculators/home-battery-sizing-calculator/index.json
- Visibility: public

## Tool capabilities

| Property | Value |
| --- | --- |
| Tool ID | `home-battery-sizing-calculator` |
| Category | calculators |
| Implementation | Registered implementation. Registration alone is not a production-quality guarantee. |
| Browser execution | Use the visible action or interactive controls. |
| Browser processing | Browser; see tool notes for network behavior. |
| HTTP API | Not callable through HTTP. |
| Browser-agent interface | run_current_tool |

### Implementation notes

Calculated on your device. Daily, evening or appliance-list loads are spread uniformly across their stated period when scaled to autonomy. Peak power is entered separately.

### Inputs and settings

No free-text input is required. Use the file inputs and/or settings below.

| Setting | Meaning | Control type | Default | Constraints |
| --- | --- | --- | --- | --- |
| `loadMode` | Load input | select | "Daily energy" | Allowed: Daily energy, Evening energy, Appliance list |
| `load` | Energy in the load period (kWh) | number | 10 | min=0 max=1000000 step=any |
| `eveningHours` | Hours represented by the evening load | number | 6 | min=0 max=24 step=any |
| `appliances` | Appliance loads | textarea | "" |  |
| `autonomyUnit` | Autonomy unit | select | "Hours" | Allowed: Hours, Days |
| `autonomy` | Autonomy duration | number | 24 | min=0 max=8760 step=any |
| `depthOfDischarge` | Allowed depth of discharge (%) | number | 80 | min=0 max=100 step=any |
| `roundTripEfficiency` | Round-trip efficiency (%) | number | 90 | min=0 max=100 step=any |
| `peakKw` | Peak simultaneous load (kW) | number | 3 | min=0 max=1000000 step=any |
| `inverterHeadroom` | Additional inverter headroom (%) | number | 0 | min=0 max=100 step=any |
| `temperatureCapacity` | Capacity retained at operating temperature (%) | number | 100 | min=0 max=100 step=any |
| `agedCapacity` | Capacity retained at the planned age (%) | number | 100 | min=0 max=100 step=any |

### Browser-agent workflow

1. Open the human page in a browser that supports WebMCP.
2. Discover the interface exposed by that page; use its actual schema.
3. Select files on the page first when the tool requires files.
4. Call `run_current_tool` with valid input and settings.
5. Inspect the returned result or error and the displayed output. Retrieve files from the displayed download links.

Calls do not automatically copy or download results. Browser permissions still apply. Interface availability alone is not proof of successful execution.

### Planning specification

Energy 0 to 1 million kWh per reference period; evening period above 0 to 24 hours; autonomy above 0 to 8,760 hours total, including day conversion; peak 0 to 1 million kW. Positive depth of discharge, round-trip efficiency and retained-capacity factors up to 100%; inverter headroom 0 to 100%. Appliance mode: up to 100 rows, 100,000 characters, quantity 1 to 10,000, power 0 to 1 million W and duty-cycle time 0 to 24 h/day. JSON report, results CSV, battery-budget CSV and appliance CSV.

This describes intended requirements. Use the implementation notes, interface schema and observed output to determine current support.

### Complete machine-readable capability record

```json
{
  "id": "home-battery-sizing-calculator",
  "category": "calculators",
  "built": true,
  "requirements": "Energy 0 to 1 million kWh per reference period; evening period above 0 to 24 hours; autonomy above 0 to 8,760 hours total, including day conversion; peak 0 to 1 million kW. Positive depth of discharge, round-trip efficiency and retained-capacity factors up to 100%; inverter headroom 0 to 100%. Appliance mode: up to 100 rows, 100,000 characters, quantity 1 to 10,000, power 0 to 1 million W and duty-cycle time 0 to 24 h/day. JSON report, results CSV, battery-budget CSV and appliance CSV.",
  "implementation": {
    "fields": [
      {
        "key": "loadMode",
        "label": "Load input",
        "value": "Daily energy",
        "type": "select",
        "values": [
          "Daily energy",
          "Evening energy",
          "Appliance list"
        ]
      },
      {
        "key": "load",
        "label": "Energy in the load period (kWh)",
        "value": 10,
        "type": "number",
        "min": 0,
        "max": 1000000,
        "step": "any",
        "showWhen": {
          "loadMode": [
            "Daily energy",
            "Evening energy"
          ]
        }
      },
      {
        "key": "eveningHours",
        "label": "Hours represented by the evening load",
        "value": 6,
        "type": "number",
        "min": 0,
        "max": 24,
        "step": "any",
        "showWhen": {
          "loadMode": [
            "Evening energy"
          ]
        }
      },
      {
        "key": "appliances",
        "label": "Appliance loads",
        "value": "",
        "type": "textarea",
        "maxLength": 100000,
        "help": "One row per appliance: name, quantity, running W and hours per day. Enter daily duty-cycle hours, not 24 hours for intermittent loads.",
        "showWhen": {
          "loadMode": [
            "Appliance list"
          ]
        }
      },
      {
        "key": "autonomyUnit",
        "label": "Autonomy unit",
        "value": "Hours",
        "type": "select",
        "values": [
          "Hours",
          "Days"
        ]
      },
      {
        "key": "autonomy",
        "label": "Autonomy duration",
        "value": 24,
        "type": "number",
        "min": 0,
        "max": 8760,
        "step": "any"
      },
      {
        "key": "depthOfDischarge",
        "label": "Allowed depth of discharge (%)",
        "value": 80,
        "type": "number",
        "min": 0,
        "max": 100,
        "step": "any"
      },
      {
        "key": "roundTripEfficiency",
        "label": "Round-trip efficiency (%)",
        "value": 90,
        "type": "number",
        "min": 0,
        "max": 100,
        "step": "any",
        "help": "A full-cycle efficiency allowance is applied to nominal storage. This conservative budget is not the same as one-way discharge efficiency."
      },
      {
        "key": "peakKw",
        "label": "Peak simultaneous load (kW)",
        "value": 3,
        "type": "number",
        "min": 0,
        "max": 1000000,
        "step": "any"
      },
      {
        "key": "inverterHeadroom",
        "label": "Additional inverter headroom (%)",
        "value": 0,
        "type": "number",
        "min": 0,
        "max": 100,
        "step": "any"
      },
      {
        "key": "temperatureCapacity",
        "label": "Capacity retained at operating temperature (%)",
        "value": 100,
        "type": "number",
        "min": 0,
        "max": 100,
        "step": "any",
        "help": "100 means no derating. Enter a manufacturer-supported retained-capacity factor to model temperature."
      },
      {
        "key": "agedCapacity",
        "label": "Capacity retained at the planned age (%)",
        "value": 100,
        "type": "number",
        "min": 0,
        "max": 100,
        "step": "any",
        "help": "100 means no ageing derating. No ageing curve is inferred."
      }
    ],
    "registrationFamily": "home-energy-planning",
    "input": false,
    "live": false,
    "presentation": "metrics",
    "note": "Calculated on your device. Daily, evening or appliance-list loads are spread uniformly across their stated period when scaled to autonomy. Peak power is entered separately.",
    "inputKeywords": [
      {
        "id": "home-energy-planning/home-battery-sizing-calculator/appliances.header",
        "kind": "header",
        "code": "HOME_ENERGY_PLANNING_APPLIANCE_HEADER",
        "fold": "lower",
        "values": {
          "appliance": [
            "appliance",
            "Appliance"
          ],
          "quantity": [
            "quantity",
            "Quantity"
          ],
          "watts": [
            "watts",
            "Watts"
          ],
          "hours": [
            "hours",
            "Hours"
          ]
        },
        "describedBy": [
          "Name the columns Appliance, Quantity, Watts and Hours, in that order, or omit the header.",
          "Appliance loads"
        ]
      }
    ],
    "experience": {
      "automatic": false,
      "single": true,
      "inputMaxLength": 1000000,
      "inputMode": "text",
      "label": "Battery load settings",
      "placeholder": "Use the fields below",
      "help": "Choose daily energy, evening energy or an appliance list in the settings. Appliance rows are name, quantity, running W and hours per day. Up to 1,000,000 characters. Review the settings before running.",
      "action": null
    },
    "mode": "explicit",
    "interactive": false
  },
  "execution": "Browser interface",
  "api": null,
  "browser_agent": {
    "supported": true,
    "name": "run_current_tool",
    "discovery": "WebMCP on the human page in a supporting browser",
    "verification": "See audit/API-AUDIT.md; availability is not verification"
  }
}
```

## Page guide

Estimate nominal battery energy and an inverter power allowance from daily, evening or appliance loads, autonomy, depth of discharge and your efficiency assumptions.

### How to use Home battery sizing calculator

1. Choose daily energy, evening energy or an appliance list.
2. Enter load energy and its reference period, or appliance name, quantity, running W and hours per day.
3. Enter autonomy in hours or days, depth of discharge, round-trip efficiency and a separate peak load.
4. Review the assumptions and energy budget, then download the JSON report and complete CSV files.

How can we improve this tool?

Report a problem or share an idea.

Please leave out private information. Your message and the tool name go to our team via PostHog.

## Useful next steps

- [Appliance electricity cost calculator](https://happytails.ai/en/calculators/appliance-electricity-cost-calculator/) ([Markdown](https://happytails.ai/en/calculators/appliance-electricity-cost-calculator.md))

- [Hot water energy calculator](https://happytails.ai/en/calculators/hot-water-energy-calculator/) ([Markdown](https://happytails.ai/en/calculators/hot-water-energy-calculator.md))

- [Insulation calculator](https://happytails.ai/en/calculators/insulation-calculator/) ([Markdown](https://happytails.ai/en/calculators/insulation-calculator.md))

## Energy and power are separate

A battery stores energy in kWh; an inverter supplies power in kW. Required delivered energy scales the average load in your stated reference period to the autonomy hours. The entered peak must cover the average and each active individual appliance, but does not need to equal every appliance running together.

### Daily and evening periods

Daily energy and appliance lists represent 24 hours. Evening energy uses your entered evening hours. Energy is spread uniformly over that period when scaled to autonomy; longer evening autonomy repeats that average rather than simulating the rest of the day. Use daily data when that is the intended load profile.

### A conservative full-cycle budget

Nominal storage divides delivered energy by depth of discharge, full-cycle round-trip efficiency and the entered temperature/age retained-capacity factors. Full-cycle efficiency is a conservative planning allowance, not a one-way discharge prediction. Enter 100% retained capacity to apply no temperature or ageing derating. Startup duration, battery discharge current, charging supply and installation protection need separate checks.