{
  "version": "1.0",
  "calculator": {
    "id": "solar-pv-self-consumption",
    "title": "Solar PV self-consumption",
    "summary": "Estimates how much of a solar system's output a household uses and how much it exports, with and without a battery.",
    "tier": "advanced",
    "description": "Estimate what proportion of a domestic solar PV system's annual output is consumed in\nthe house and what proportion is exported, using the lookup tables in MGD 003.\n\nThe tables are not a model. They come from half-hourly monitoring of real British households by\nLoughborough University, with battery behaviour modelled on top, so they carry the real shape of\ndomestic demand: a peak before the sun is up, another after it has gone, and a quiet middle of the day.\n\nThree things index them. The annual generation, which comes from the MIS 3002 output estimate. The\nhousehold's annual consumption from a bill based on actual meter readings, which defaults to the\nBritish average of 3,500 kWh where it is unknown. And the weekday occupancy pattern, which is\n'home_all_day', 'in_half_the_day' or 'out_all_day'; where the pattern is unknown MGD 003 says to use\nthe middle one, and that is what an omitted value resolves to.\n\nBattery capacity is the USABLE capacity, which is smaller than the figure printed on the battery.\nSupplying import and export prices adds a value in pounds to the result.\n\nNote that self-consumption is not the same as independence from the grid, and the result reports both.",
    "standard": "MGD 003",
    "category": "batteries",
    "webPath": "/calculators/solar-pv-self-consumption",
    "example": {
      "annualGenerationKwh": 3600,
      "annualConsumptionKwh": 3500,
      "occupancy": "out_all_day",
      "batteryKwh": 5,
      "importPricePerKwh": 0.27,
      "exportPricePerKwh": 0.15
    },
    "reference": {
      "occupancyArchetypes": [
        {
          "value": "home_all_day",
          "label": "Home all day",
          "description": "At least one person is in the house between 9am and 5pm on weekdays."
        },
        {
          "value": "in_half_the_day",
          "label": "In half the day",
          "description": "The house is empty for about half of each weekday, either the morning or the afternoon."
        },
        {
          "value": "out_all_day",
          "label": "Out all day",
          "description": "The house is empty on weekdays."
        }
      ]
    },
    "inputSchema": {
      "type": "object",
      "properties": {
        "annualGenerationKwh": {
          "type": "number",
          "description": "Expected annual AC output of the PV system in kWh, as produced by the MIS 3002 estimation method. Required."
        },
        "annualConsumptionKwh": {
          "type": "number",
          "description": "The household's annual electricity consumption in kWh, from a bill based on actual meter readings. Defaults to 3500, which MGD 003 uses where the figure is unknown."
        },
        "occupancy": {
          "type": "string",
          "description": "Weekday occupancy pattern: 'home_all_day', 'in_half_the_day' or 'out_all_day'. Defaults to 'in_half_the_day', which is what MGD 003 says to use when the pattern is unknown."
        },
        "batteryKwh": {
          "type": "number",
          "description": "Usable capacity of any battery in kWh, which is smaller than the headline capacity. Omit or use 0 for no battery."
        },
        "importPricePerKwh": {
          "type": "number",
          "description": "What the household pays for a unit of grid electricity, in pounds. Optional; supplying it adds a value to the result."
        },
        "exportPricePerKwh": {
          "type": "number",
          "description": "What the household is paid for a unit exported, in pounds. Optional."
        }
      },
      "required": [
        "annualGenerationKwh"
      ],
      "additionalProperties": false
    },
    "outputSchema": {
      "type": "object",
      "properties": {
        "occupancy": {
          "type": "string"
        },
        "occupancyLabel": {
          "type": "string"
        },
        "annualGenerationKwh": {
          "type": "number"
        },
        "annualConsumptionKwh": {
          "type": "number"
        },
        "consumptionAssumed": {
          "type": "boolean",
          "description": "True when the 3500 kWh default stood in for a figure the caller did not give."
        },
        "batteryKwh": {
          "type": "number"
        },
        "selfConsumptionPercent": {
          "type": "number",
          "description": "Proportion of generation used in the home instead of exported."
        },
        "selfConsumedKwh": {
          "type": "number"
        },
        "exportedKwh": {
          "type": "number"
        },
        "importedKwh": {
          "type": "number",
          "description": "Units still bought from the grid over the year."
        },
        "gridIndependencePercent": {
          "type": "number",
          "description": "Proportion of the household's own consumption met by the system instead of by the grid. Different from self-consumption, and usually smaller."
        },
        "withoutBatteryPercent": {
          "type": "number",
          "description": "What the same system would self-consume with no battery."
        },
        "batteryGainKwh": {
          "type": "number",
          "description": "Extra units kept in the house each year because of the battery."
        },
        "annualBillSaving": {
          "type": "number",
          "description": "Value of the units not bought, in pounds. Only present when an import price was given."
        },
        "annualExportIncome": {
          "type": "number",
          "description": "Value of the units exported, in pounds. Only present when an export price was given."
        },
        "annualValue": {
          "type": "number",
          "description": "The two added together."
        },
        "method": {
          "type": "string"
        },
        "references": {
          "type": [
            "null",
            "array"
          ],
          "items": {
            "type": "object",
            "properties": {
              "document": {
                "type": "string"
              },
              "title": {
                "type": "string"
              },
              "url": {
                "type": "string"
              },
              "clause": {
                "type": "string"
              }
            },
            "required": [
              "document",
              "title",
              "url"
            ],
            "additionalProperties": false
          }
        },
        "notes": {
          "type": [
            "null",
            "array"
          ],
          "items": {
            "type": "string"
          }
        }
      },
      "required": [
        "occupancy",
        "occupancyLabel",
        "annualGenerationKwh",
        "annualConsumptionKwh",
        "consumptionAssumed",
        "batteryKwh",
        "selfConsumptionPercent",
        "selfConsumedKwh",
        "exportedKwh",
        "importedKwh",
        "gridIndependencePercent",
        "withoutBatteryPercent",
        "method",
        "references",
        "notes"
      ],
      "additionalProperties": false
    }
  },
  "url": "https://ampworth.com/api/v1/calculators/solar-pv-self-consumption",
  "webUrl": "https://ampworth.com/calculators/solar-pv-self-consumption",
  "exampleUrl": "https://ampworth.com/api/v1/calculators/solar-pv-self-consumption?annualGenerationKwh=3600\u0026annualConsumptionKwh=3500\u0026occupancy=out_all_day\u0026batteryKwh=5\u0026importPricePerKwh=0.27\u0026exportPricePerKwh=0.15",
  "method": "POST",
  "contentType": "application/json",
  "notice": "These calculators follow the published MCS methods, for understanding a system and checking a quotation. Anything that gets installed still needs a design and a site survey from a certified installer."
}