{
 "site": "https://batterypayback.co.uk",
 "generated": "2026-10-26",
 "status": "live",
 "note": "Only facts whose quote was found verbatim at the source are included.",
 "model": "see /how-we-calculate/; reference implementation /assets/rekenaar.js (BP.bereken)",
 "model_version": "2026-10-23 (monthly PVGIS profile, optional grid-charging power limit, optional load shifting without a battery)",
 "solar_profiles": [
  {
   "city": "London",
   "kwh_per_kwp_year": 1018.84,
   "monthly_kwh_per_kwp": [
    40.71,
    53.19,
    86.55,
    114.55,
    119.45,
    122.59,
    123.21,
    110.37,
    95.22,
    68.51,
    48.18,
    36.33
   ],
   "evidence": {
    "statement": "PVGIS estimates 1018.84 kWh a year for 1 kWp of solar panels in London, facing south at 35° with 14% system losses.",
    "quote": "\"E_y\":1018.84",
    "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/PVcalc?lat=51.507&lon=-0.128&peakpower=1&loss=14&angle=35&aspect=0&outputformat=json",
    "source_type": "officieel (EU JRC, PVGIS)",
    "pdf": false,
    "read_on": "2026-10-22",
    "getoetst_via": "toets_codex.py (Claude)",
    "check": "ok"
   }
  },
  {
   "city": "Cardiff",
   "kwh_per_kwp_year": 1041.7,
   "monthly_kwh_per_kwp": [
    36.54,
    53.79,
    89.22,
    119.92,
    132.51,
    131.04,
    129.28,
    113.09,
    96.01,
    65.34,
    42.69,
    32.26
   ],
   "evidence": {
    "statement": "PVGIS estimates 1041.7 kWh a year for 1 kWp of solar panels in Cardiff, facing south at 35° with 14% system losses.",
    "quote": "\"E_y\":1041.7",
    "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/PVcalc?lat=51.481&lon=-3.179&peakpower=1&loss=14&angle=35&aspect=0&outputformat=json",
    "source_type": "officieel (EU JRC, PVGIS)",
    "pdf": false,
    "read_on": "2026-10-22",
    "getoetst_via": "toets_codex.py (Claude)",
    "check": "ok"
   }
  },
  {
   "city": "Birmingham",
   "kwh_per_kwp_year": 968.06,
   "monthly_kwh_per_kwp": [
    37.24,
    51.59,
    84.07,
    108.17,
    117.29,
    117.05,
    118.06,
    106.16,
    90.13,
    62.79,
    42.37,
    33.15
   ],
   "evidence": {
    "statement": "PVGIS estimates 968.06 kWh a year for 1 kWp of solar panels in Birmingham, facing south at 35° with 14% system losses.",
    "quote": "\"E_y\":968.06",
    "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/PVcalc?lat=52.486&lon=-1.89&peakpower=1&loss=14&angle=35&aspect=0&outputformat=json",
    "source_type": "officieel (EU JRC, PVGIS)",
    "pdf": false,
    "read_on": "2026-10-22",
    "getoetst_via": "toets_codex.py (Claude)",
    "check": "ok"
   }
  },
  {
   "city": "Manchester",
   "kwh_per_kwp_year": 886.08,
   "monthly_kwh_per_kwp": [
    26.87,
    44.61,
    78.06,
    104.7,
    113.1,
    110.69,
    108.09,
    96.99,
    80.98,
    56.38,
    37.45,
    28.18
   ],
   "evidence": {
    "statement": "PVGIS estimates 886.08 kWh a year for 1 kWp of solar panels in Manchester, facing south at 35° with 14% system losses.",
    "quote": "\"E_y\":886.08",
    "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/PVcalc?lat=53.48&lon=-2.242&peakpower=1&loss=14&angle=35&aspect=0&outputformat=json",
    "source_type": "officieel (EU JRC, PVGIS)",
    "pdf": false,
    "read_on": "2026-10-22",
    "getoetst_via": "toets_codex.py (Claude)",
    "check": "ok"
   }
  },
  {
   "city": "Edinburgh",
   "kwh_per_kwp_year": 902.72,
   "monthly_kwh_per_kwp": [
    28.69,
    46.39,
    78.63,
    105.86,
    119.55,
    110.93,
    113.05,
    101.94,
    82.0,
    55.91,
    37.56,
    22.21
   ],
   "evidence": {
    "statement": "PVGIS estimates 902.72 kWh a year for 1 kWp of solar panels in Edinburgh, facing south at 35° with 14% system losses.",
    "quote": "\"E_y\":902.72",
    "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/PVcalc?lat=55.953&lon=-3.188&peakpower=1&loss=14&angle=35&aspect=0&outputformat=json",
    "source_type": "officieel (EU JRC, PVGIS)",
    "pdf": false,
    "read_on": "2026-10-22",
    "getoetst_via": "toets_codex.py (Claude)",
    "check": "ok"
   }
  },
  {
   "city": "Belfast",
   "kwh_per_kwp_year": 918.76,
   "monthly_kwh_per_kwp": [
    29.57,
    47.45,
    80.63,
    108.14,
    122.36,
    116.17,
    110.04,
    100.63,
    81.28,
    58.08,
    38.08,
    26.32
   ],
   "evidence": {
    "statement": "PVGIS estimates 918.76 kWh a year for 1 kWp of solar panels in Belfast, facing south at 35° with 14% system losses.",
    "quote": "\"E_y\":918.76",
    "source_url": "https://re.jrc.ec.europa.eu/api/v5_3/PVcalc?lat=54.597&lon=-5.93&peakpower=1&loss=14&angle=35&aspect=0&outputformat=json",
    "source_type": "officieel (EU JRC, PVGIS)",
    "pdf": false,
    "read_on": "2026-10-22",
    "getoetst_via": "toets_codex.py (Claude)",
    "check": "ok"
   }
  }
 ],
 "inputs": {
  "verbruik_kwh_jaar": "yearly use, kWh (your input)",
  "aandeel_overdag": "share of use in daylight, 0-1 (your input)",
  "aandeel_goedkope_uren": "share of use already in cheap hours, 0-1",
  "opwek_kwh": "yearly solar kWh, or 12 monthly values",
  "accu_bruikbaar_kwh": "usable battery kWh",
  "rendement_rondgang": "0-1",
  "prijs_piek_p": "p/kWh",
  "prijs_goedkoop_p": "p/kWh",
  "seg_p": "p/kWh",
  "accu_prijs_gbp": "installed price, GBP",
  "jaarlijkse_afname": "optional yearly reduction of saving, 0-1",
  "laadvermogen_kw": "optional battery charging power, kW (with the next field)",
  "goedkope_uren_per_dag": "optional length of the cheap window, hours; grid charging is capped at power x hours a night",
  "verschuifbaar_aandeel": "optional share of evening use moved to cheap hours without a battery, 0-1; applied with and without the battery (result: alleen_verschuiven_gbp_jaar)"
 },
 "sourced_defaults": {
  "prijs_piek_p": {
   "value": 26.32,
   "unit": "p/kWh",
   "evidence": {
    "statement": "Ofgem gives an average electricity unit rate of 26.32 pence per kWh and 54.83 pence daily standing charge for Direct Debit across England, Scotland and Wales.",
    "quote": "26.32 pence per kWh 54.83 pence daily standing charge",
    "source_url": "https://www.ofgem.gov.uk/your-energy-supply/your-energy-bill/energy-price-cap-unit-rates-and-standing-charges",
    "source_type": "officieel",
    "pdf": false,
    "valid": {
     "from": "2026-10-01",
     "to": "2026-12-31",
     "quote": "Energy price cap from 1 October to 31 December 2026"
    },
    "read_on": "2026-10-19",
    "check": "ok"
   }
  },
  "battery_cost_range": {
   "evidence": {
    "statement": "Energy Saving Trust states that battery storage tends to cost around £5,000 to £8,000.",
    "quote": "Battery storage tends to cost around £5,000 to £8,000.",
    "source_url": "https://energysavingtrust.org.uk/advice/solar-panels/?loc=england",
    "source_type": "officieel",
    "pdf": false,
    "read_on": "2026-10-19",
    "check": "ok"
   }
  }
 }
}