Engineering Compliance & Standards

Transparent Sizing Methodology (PEC, TESDA & NEC Compliant)

ProjectSolar operates on standardized, deterministic electrical engineering calculations—never black-box estimates. Below is our verified 14-formula mathematical framework.

Formula 1 & 2: Photovoltaic Array Sizing

Solar DC Power (Watts Peak)

Your monthly kilowatt-hours are divided by 30 to determine daily consumption. Sizing applies your local Peak Sun Hours (PSH) and a conservative 1.30 safety factor:

P_pv = (Daily Wh ÷ PSH) × 1.30

This accounts for 20% system derating due to high ambient temperature coefficients, inverter conversion losses (~97%), dust/soiling, and wire resistance.

Formula 3 & 4: Module Quantity & Footprint

Tier-1 Solar Module Selection

Total peak power is matched against high-efficiency 550W monocrystalline half-cell modules:

Module Count = ceil(P_pv ÷ 550 W)

Unshaded roof area is estimated using 2.38 m² per panel (including inter-panel spacing and maintenance walkways).

Formula 5, 6 & 7: LiFePO4 Battery Storage

Battery Bank Autonomy (Ah @ 48V)

Energy storage is calculated for safe cyclic life using modern Lithium Iron Phosphate (LiFePO4) chemistry:

Capacity (Ah) = Night Wh ÷ (DoD 90% × Eff 92% × 48V)

Standardized to 51.2V 100Ah (5.12 kWh) modular server racks with over 6,000 cycles (15+ year lifespan).

Formula 8 & 11: DC Breaker & Disconnect

PEC Art 6.90 DC Overcurrent

Philippine Electrical Code (PEC) and NEC 690 require DC breakers between the battery bank, inverter, and charge controller to be sized with a 125% continuous duty margin:

DC Breaker = (Inverter Power ÷ DC Voltage) × 125%

Formula 12: PV String Fusing & Breakers

Array Current Protection

Solar PV string combiner boxes and DC disconnect switches are rated against the maximum string short-circuit and peak operating current:

PV Breaker = Total Imp × 125%

Formula 13: AC Interconnect Breaker

Utility Grid Synchronization

AC output breakers connecting the inverter's main AC output to the building distribution panelboard are sized for full continuous load:

AC Breaker = (Inverter Watts ÷ 230V) × 125%

Regulatory Alignment

Electrical Code Standards Built Into Every Calculation

🇵🇭 Philippine Electrical Code (PEC 2017)

Article 6.90 defines requirements for solar photovoltaic systems including grounding, rapid shutdown, and conductor ampacity sizing for tropical ambient temperatures.

📜 TESDA Solar Photovoltaic NC II

Standardized training formulas for certified solar technicians and installers in the Philippines, ensuring consistent calculation of series/parallel strings and controller current.

🌐 National Electrical Code (NEC 690)

International baseline for inverter disconnects, arc-fault circuit interrupter (AFCI) safety, and maximum 3% voltage drop index (VDI) design on conductor runs.

See the Engineering Engine in Action

Launch our solar calculator to see all 14 formulas calculate your exact breaker ratings, wire gauges, and cash-flow projections in real-time.

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