Educational Purpose
This guide provides general educational principles for estimating energy needs and evaluating equipment. Because roof pitch, local shading, seasonal dust (harmattan), and electrical wiring differ across properties, exact system sizing and installation design should always involve professional on-site appraisal.
1. Essential Solar Components
A complete solar power installation comprises four main building blocks:
- Photovoltaic (PV) Panels: Convert incident sunlight into direct current (DC) electricity using semiconductor solar cells.
- Solar Inverter: Converts DC electricity into alternating current (AC) at standard voltage (230V, 50Hz) for household appliances.
- Battery Energy Storage: Stores daytime excess generation to power loads during nighttime hours and grid outages.
- Balance of System (BOS): Aluminum mounting rails, DC/AC circuit breakers, surge protection devices, isolators, and heavy-duty cabling.
Core Components
2. Estimating Energy Needs & Sizing
System sizing starts with a daily energy audit:
- Step 1 — Calculate Watt-Hours (Wh): Multiply each appliance's rated wattage (W) by its daily operating hours. For example, a 150W refrigerator running 10 hours of active compressor time consumes approximately 1,500Wh (1.5kWh) per day.
- Step 2 — Account for System Losses: Divide total daily energy consumption by an efficiency factor (typically 0.75 to 0.85) to compensate for inverter conversion and wiring losses.
- Step 3 — Solar Array Sizing: Northwestern Nigeria experiences high annual solar irradiance, averaging approximately 5 to 6 peak sun hours per day. Dividing adjusted daily watt-hours by 5 gives the minimum solar panel capacity required in watts-peak (Wp).
Sizing Principles
3. Battery Chemistry & Lifespan
Selecting the appropriate battery technology affects long-term cost of ownership:
- Lithium Iron Phosphate (LiFePO4): High thermal stability, typically 3,000 to 6,000 charge cycles at 80% Depth of Discharge (DoD). Higher initial investment, but offers the lowest cost per cycle over 8 to 12 years of service.
- Tubular / Gel Lead-Acid: Established technology with lower upfront purchase price, but delivers 500 to 1,200 cycles at 50% DoD and requires adequate ventilation and periodic replacement every 2 to 4 years.
- Usable vs Nominal Capacity: A 5kWh lead-acid battery provides roughly 2.5kWh usable energy at 50% DoD, whereas a 5kWh LiFePO4 battery safely delivers about 4kWh at 80% DoD.
Storage Technology
4. Questions to Ask Your Installer
Before signing an agreement or making a deposit, ensure you have clear answers to these critical questions:
- Warranties: What is the written manufacturer warranty on panels (typically 20–25 years linear power warranty) versus inverters (typically 5–10 years) and batteries?
- Electrical Protection: Does the quotation itemise AC and DC surge protection devices (SPDs), lightning protection, and proper earth grounding?
- Local Service & Support: Who handles warranty claims and repairs if an inverter fault occurs after installation?
- Expansion Capability: Can additional solar panels or battery capacity be easily connected in the future without replacing the inverter?
Installer Checklist
