What size solar system do I need for my house?

Inverter size, battery capacity and panel count are three different questions. Getting one right and the others wrong is why systems fail at 3 a.m.

Sizing a solar system for a Nigerian home, 16kW inverter with lithium battery storage

Three numbers, not one

People ask ‘what size solar do I need?’ as though it is a single number. It is three:

  • Inverter size (kW): set by your peak simultaneous demand, dominated by air-conditioner start-up surge.
  • Battery capacity (kWh): set by how much energy you use while the sun is down.
  • Panel count (kWp): set by how fast you need that battery refilled the next day.

An oversized inverter with a small battery empties before morning. A large battery with too few panels never refills. Both are common, and both are avoidable.

A practical guide by property

  • 3–5 kVA: lights, fans, TVs, one fridge/freezer, sometimes one 1 HP AC
  • 8–10 kW: a full family home with 2 fridges, 2 freezers and two to three 1.5 HP ACs
  • 12–16 kW: a large home or duplex with three to five 1.5 HP ACs and a pumping machine
  • 20–30 kW: an estate residence, office or small commercial building, often three-phase
  • 50 kW+: hotels, schools, hospitals, warehouses and industrial facilities

Why air conditioning decides everything

A 1.5 HP inverter AC draws roughly 1.1–1.3 kW while running. Three of them is close to 4 kW of continuous demand before you have switched on a single light.

This is why we ask for the horsepower of each unit rather than just how many rooms you have. A 3 HP unit and a 1 HP unit place completely different demands on the same system, as we found on a two-bedroom Airbnb running two 1.5 HP units and one 3 HP unit.

Get it assessed rather than guessed

Our load assessment is free, and it is genuinely diagnostic; our engineers regularly tell customers they need less than they were about to buy.

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