We sized a system for a customer in Yaba last month, and it is a useful example. The shop sells cold drinks and provisions, runs a small POS terminal, two ceiling fans, six LED lights, and a single chest freezer for drinks.
Step one: list the loads. Six 12 W LED lights, two 60 W ceiling fans, a 50 W POS terminal, a 150 W router, and a 200 W chest freezer running about a third of the time. Continuous load: 6 × 12 + 2 × 60 + 50 + 150 = 332 W. Plus the freezer cycling on about 8 hours a day, average draw about 67 W. Total continuous: around 400 W.
Step two: surge. The freezer compressor draws 4 to 6 times its running wattage on startup, so about 800 to 1,200 W of surge for a few seconds. That is the number to size the inverter around. A 1.5 kW pure sine inverter handles this comfortably with headroom.
Step three: daily energy. About 6 to 7 kWh, dominated by the freezer and the fans during open hours. We spec 10 kWh of LiFePO4 battery to give the customer a full day's autonomy and protect the battery from deep discharge.
Step four: panels. Lagos gets good sun, but with afternoon clouds, plan for 4 peak sun hours. To cover 6 kWh a day with system losses, you need about 1.8 kW of panels. Four 450 W panels fit comfortably on the shop roof.
Total system: 1.5 kW hybrid inverter, 10 kWh battery, four 450 W panels, basic mounting and cabling. That is what we shipped. The customer reported back after two months that the shop has not touched the generator since installation.