Energy
Solar Power for Homes in Nigeria: How to Size a System That Works
A home solar system works when the inverter, batteries and panels are sized to what the house actually uses. Here is how the sizing works, with a worked example.
Many Nigerian homes that bought solar are disappointed with it. The inverter trips when the pumping machine starts, the batteries are flat by midnight, or the panels never quite recharge them. In almost every case the equipment is not faulty. The system was sized for a guess instead of for the house.
This guide explains how a home solar system should be sized, with a worked example, and what to check before accepting a quote.
The three numbers that matter
A home solar system has three main parts, and each is sized against a different number:
- The inverter is sized for peak power: the most the house draws at any moment, in kilowatts (kW).
- The batteries are sized for energy through the night: how much the house uses when the sun is down, in kilowatt-hours (kWh).
- The panels are sized for daily energy: enough to run the house during the day and recharge the batteries.
Mixing these up is the most common cause of disappointment. A 5kW inverter does not mean the house can run for five hours; it means it can supply up to 5kW at once.
Step 1: list what must run
Start with the loads that matter during an outage. List each appliance, its power and how long it runs.
- Lights, fans, TVs and phone charging are small loads.
- Fridges and freezers run all day but cycle on and off.
- Air conditioners, water heaters, pumping machines and electric cookers are heavy loads.
Decide early which heavy loads solar must carry. Running every air conditioner through the night needs a much larger and more expensive system than running lights, fans, the fridge and one bedroom AC. Our guide to electrical load planning explains how professionals measure this properly.