🎓 Lesson 1
D1
Getting Started with Solar PV System Sizing
Solar PV system sizing is figuring out how many solar panels and how much battery storage you need to reliably power a building or device using sunlight.
🎯 Learning Objectives
- ✓ Calculate daily energy consumption from appliance-level load data
- ✓ Estimate peak sun hours for a given location using standard meteorological datasets
- ✓ Design a PV array size (kWp) and battery capacity (kWh) to meet defined autonomy and depth-of-discharge requirements
- ✓ Analyze system losses (soiling, temperature, wiring, inverter) and apply derating factors to nominal ratings
- ✓ Apply IEEE 1547 and NEC Article 690 requirements to validate interconnection-ready system specifications
📖 Why This Matters
Getting solar sizing wrong is the #1 cause of underperforming or failed off-grid and grid-tied projects—especially in remote mining camps where diesel backup is costly and unreliable. A correctly sized PV system ensures continuous power for ventilation, communications, and safety systems, reduces operational emissions by up to 80%, and delivers ROI within 3–5 years. In blasting operations, reliable solar-powered monitoring and telemetry can prevent hazardous delays and unplanned downtime.
📘 Core Principles
PV system sizing rests on three foundational pillars: (1) Load characterization—quantifying energy demand in kWh/day with temporal profiling (peak vs. base load); (2) Resource assessment—translating geographic location into usable solar insolation (kWh/m²/day), accounting for tilt, azimuth, shading, and seasonal variation; and (3) System efficiency chain—modeling cumulative losses across modules (temperature, mismatch), wiring (voltage drop), inverters (conversion efficiency), and batteries (round-trip efficiency, DoD limits). Modern practice uses probabilistic methods (e.g., PVWatts, SAM) but requires manual verification to meet mining site ruggedness and redundancy standards.
📐 PV Array Sizing Formula
The fundamental sizing equation adjusts required DC capacity to account for all real-world losses. It ensures the installed array produces enough energy after degradation and inefficiencies to meet the AC load demand.
DC Array Size (kWp)
P_{DC} = \frac{E_{AC} / \eta_{inv}}{PSH \times DR}Calculates minimum DC-rated photovoltaic capacity required to meet AC energy demand after accounting for inverter efficiency and system losses.
Variables:
| Symbol | Name | Unit | Description |
|---|---|---|---|
| P_{DC} | DC Array Size | kWp | Total nameplate DC power of PV modules at STC |
| E_{AC} | Daily AC Energy Demand | kWh/day | Total usable AC energy required per day |
| \eta_{inv} | Inverter Efficiency | decimal | AC output / DC input ratio, typically 0.92–0.98 |
| PSH | Peak Sun Hours | h/day | Site-specific average daily solar insolation equivalent at 1 kW/m² |
| DR | System Derate Factor | decimal | Product of individual loss factors: temp, soiling, mismatch, wiring, etc. |
Typical Ranges:
Desert mining site (low humidity, high dust): 0.75 – 0.82
Temperate, well-maintained site: 0.83 – 0.88
💡 Worked Example
Problem: A remote mine camp requires 24 kWh/day AC load. Site has 4.8 peak sun hours (PSH), inverter efficiency = 95%, system losses = 14% (soiling, temp, wiring), and module STC rating = 400 W. Calculate minimum kWp needed.
1.
Step 1: Convert AC load to DC equivalent: 24 kWh/day ÷ 0.95 = 25.26 kWh/day DC
2.
Step 2: Apply total derate factor: 1 − 0.14 = 0.86 → effective yield per kWp = 4.8 × 0.86 = 4.128 kWh/kWp/day
3.
Step 3: Size array: 25.26 kWh/day ÷ 4.128 kWh/kWp/day = 6.12 kWp
4.
Step 4: Round up to nearest module count: 6.12 kWp ÷ 0.4 kW/module = 15.3 → use 16 modules (6.4 kWp)
Answer:
The result is 6.12 kWp, which rounds to 6.4 kWp (16 × 400 W modules), satisfying both load and redundancy margin for critical mine infrastructure.
🏗️ Real-World Application
At Newmont’s Boddington Gold Mine (Western Australia), a 2.1 MW solar + 4 MWh battery hybrid system was sized to offset 15% of daytime grid demand. Engineers used 12-month TMY3 weather data, modeled shading from adjacent processing plant structures via LiDAR, applied 12% total losses (including 5°C above STC temperature penalty), and included 20% oversizing to accommodate dust accumulation during dry season—ensuring ≥98% dispatch reliability across all seasons per ISO 50001 energy management verification.
🔧 Interactive Calculator
🔧 Open Solar PV System Sizing Calculator📋 Case Connection
📋 Solar PV System Sizing in Large-Scale Industrial Projects
Complex engineering requirements at scale
📋 Small-Scale Solar PV System Sizing Implementation
Limited resources and tight budget
📋 Solar PV System Sizing in Challenging Environments
Environmental and terrain challenges
📋 Cost Optimization in Solar PV System Sizing
Maintaining quality while reducing costs