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Calculator Methodology

Our Solar Savings Calculator generates estimates using proven photovoltaic modeling practices, Philippine-specific energy data, and industry-standard financial formulas. The goal is to give you a realistic preview of your potential cost savings and environmental impact before a full engineering assessment.

We combine your electricity usage with current local rates, solar production factors, and system performance assumptions to calculate:

  • Annual Energy Consumption — based on your bill and the actual kWh rate in your area.
  • Solar Offset Potential — the portion of your consumption a PV system can realistically cover.
  • Annual and Lifetime Savings — factoring in self-consumption, export credits, tariff escalation, and panel performance over 25 years.
  • Environmental Benefits — your estimated CO₂ reduction, expressed in kilograms and relatable equivalents (trees planted, cars removed).

Our methodology adjusts for different customer segments — whether you’re a homeowner, a business, an off-grid facility, or a solar plant operator — so that your results reflect typical usage patterns, system sizes, and energy pricing relevant to your profile.

1. Core Financial & Energy Formulas

1.1 Annual Energy Consumption (kWh/year)

Annual kWh = ((Monthly Bill − Fixed Charges) / Electricity Rate) × 12
  • Electricity Rate: ₱12.64/kWh (Meralco Residential Rate, July 2025)
  • Fixed Charges: Metering + service fees from your bill.

1.2 Annual Savings (₱/year)

Annual Savings = (Self-consumed kWh × Timport) + (Exported kWh × Texport) − O&M Cost
  • Self-Consumption Ratio (SC): Residential 0.50–0.65; C&I 0.80–0.95; Off-grid ~1.0.
  • Export Credit (Texport): Based on local net-metering/net-billing rules.

1.3 Lifetime Savings (₱)

Lifetime Savings = Σ (Annual Savings) from t=1 to 25
  • Tariff Escalation: 3%/year (industry benchmark)
  • PV Degradation: 0.5%/year (NREL, 2013)
  • System Lifetime: 25 years (Tier-1 module warranty)

1.4 Environmental Impact (CO₂ Reduction)

CO₂ Reduction (kg/year) = Annual kWh Offset × Emission Factor
  • Emission Factor: 0.69 kg CO₂/kWh (DOE NGEF 2019–2021)
  • Converted to relatable equivalents in the calculator output (trees planted, cars removed).
2. Segment-Specific Adjustments

Our calculator tailors its assumptions based on the customer profile you select:

  • Residential: Higher offset %, export credits often lower than import rates, battery option increases SC ratio.
  • Commercial & Industrial: Adds peak-shaving benefit for demand charges; adjusts for Time-of-Use (TOU) rates.
  • Remote/Off-Grid: Compares PV LCOE with diesel generation (fuel, O&M, logistics); battery-inclusive PR adjustment.
  • O&M Operators: Values yield gains and cost reductions from improved maintenance.
  • Circular Economy: Uses value-recovery calculation for second-life PV modules.
3. Key Assumptions
ParameterDefault ValueSource
Electricity Rate₱12.64/kWhMeralco Advisory, July 2025
Grid CO₂ Factor0.69 kg/kWhDOE NGEF 2019–2021
PV System Lifetime25 yearsTier-1 Manufacturer Warranty
PV Degradation0.5%/yearNREL Study (Jordan & Kurtz, 2013)
Tariff Escalation3%/yearIndustry Benchmark

Note: These figures are indicative. A site-specific engineering study will refine these estimates using detailed load data, shading analysis, and actual installation parameters.

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