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Tool 12: Renewable Energy & Solar EPC

Commercial Rooftop Solar PV Array & Inverter Sizing

Estimates optimum DC solar array capacity (kWp), module count, commercial on-grid inverter AC rating, monthly generation yields, roof footprint utilization, and annual carbon offsets for industrial and commercial facilities.

✔ 1. Formula Verified → ⚡ 2. Engineering Screening → 📐 3. Standards Referenced (MNRE / IEC 62548) → ⚖ 4. Engineer Review Required
⚙ Solar Facility Design Parameters
kWh (Units)
Average monthly energy bill consumption targeted for solar offset.
Sq. Ft.
Usable RCC roof, metal sheet shed, or ground area free of shadow obstructions.
kWh/m²/day
Annual average daily solar irradiation (typically 4.5–5.2 PSH across Northern & Central India).
Ratio
System efficiency accounting for temperature, dust/soiling, inverter, and AC/DC wiring losses (typically 0.75–0.80).
Ratio
Optimum inverter loading ratio to maximize early morning and evening generation (typically 1.15–1.25).
Watts
Modern high-efficiency Mono PERC / TOPCon bifacial module wattage (e.g. 545–580 Wp).
kg/kWh
Configurable baseline per CEA CO2 Baseline Database for the Indian Power Sector (default 0.82 kg CO2/kWh).
📊 Solar PV System Sizing Sheet
Preliminary Screening
Recommended DC Capacity & Inverter Rating
133.65 kWp
Selected Standard Inverter: 125 kW AC (Calc: 111.4 kW AC)
Required PV Modules
243 Modules
Est. Monthly Generation
15,220 kWh
Est. Annual Generation
182,641 kWh
Annual CO2 Offset
149.8 Tons/yr
Rooftop Area Footprint
6,804 sq.ft (56.7% of roof utilized)
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Governing Engineering Standards & Calculation Model

Governing Standards & References

  • MNRE Guidelines: Grid-Connected Rooftop Solar Power Plant Technical Specifications.
  • CEA Regulations 2013/2019: Technical Standards for Connectivity of Distributed Generation Resources.
  • IEC 62548 / IS 16221: Photovoltaic (PV) arrays — Design requirements.
  • IEC 62109-1/2: Safety of power converters for use in photovoltaic power systems.

Engineering Equations & Derivations

Annual Generation Target: kWh_annual = Monthly_kWh × 12
Required DC Capacity: P_DC_req = kWh_annual / (PSH × 365 × PR)
Mathematical Min Modules: N_min = ⌈(P_DC_req × 1000) / Module_Wp⌉
Selected Layout: 9 strings × 27 modules = 243 modules (133.65 kWp)
Standard String Inverter: 125 kW (DC:AC ratio = 1.07)
Verified Annual Yield: 133.65 × 4.8 × 365 × 0.78 = 182,641 kWh/yr
CO2 Offset: (Annual_kWh × 0.82) / 1000 [Tons/yr]

Engineering Note: 240 modules (132.00 kWp) is the exact mathematical minimum. 243 modules (133.65 kWp, 9 strings × 27 modules) is a preliminary selected layout for symmetrical combiner box and inverter MPPT input sizing. Because module Voc, Vmp, temperature coefficients, and detailed inverter MPPT voltage windows are project-specific, this is classified as preliminary engineering screening and not a final detailed string electrical design.

⚖ Statutory Notice & Engineering Disclaimer (Tier D Integration)

Solar generation figures and string counts are preliminary screening estimates based on average meteorological insolation (PSH). Detailed electrical string design requires verifying Voc at minimum ambient site temperatures and Vmp at maximum cell operating temperatures against inverter MPPT tracking windows. Actual PV yields depend on precise panel tilt angle, azimuth orientation, shading analysis, DC:AC clipping, and seasonal degradation. Net metering or gross metering sanction is subject to local SERC regulations and DISCOM transformer capacity limits. Rooftop structural dead/wind load adequacy must be certified by a licensed structural engineer prior to installation.