Abana (Kastamonu) Enerji & Güneş Enerjisi İçin Vibe Coding

// lib/solar/roiCalculator.ts
export function calculateSolarROI(monthlyBillTL: number, city: string, roofAreaM2: number) {
  const electricityKwhPrice = 4.2; // TL per kWh commercial tariff
  const monthlyKwh = monthlyBillTL / electricityKwhPrice;
  const annualKwhNeeded = monthlyKwh * 12;

  // City solar radiation factor (kWh/kWp/year)
  const radiationFactor = { "izmir": 1550, "antalya": 1650, "ankara": 1400, "bursa": 1350 }[city.toLowerCase()] || 1400;

  const requiredKwp = Math.round(annualKwhNeeded / radiationFactor);
  const maxKwpOnRoof = Math.floor(roofAreaM2 / 6.5); // ~6.5m2 per kWp
  const effectiveKwp = Math.min(requiredKwp, maxKwpOnRoof);

  const estimatedCostUSD = effectiveKwp * 650; // $650 per kWp turnkey EPC
  const annualSavingUSD = (effectiveKwp * radiationFactor * electricityKwhPrice) / 36; // USD/TL

  return {
    installedPowerKwp: effectiveKwp,
    annualProductionKwh: effectiveKwp * radiationFactor,
    totalInvestmentUSD: estimatedCostUSD,
    paybackYears: round(estimatedCostUSD / annualSavingUSD, 1),
    co2SavedTons: round((effectiveKwp * radiationFactor * 0.45) / 1000, 1)
  };
}