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What Size Inverter for a 3 Bedroom Flat in Nigeria?
This is the most common question we get, almost word for word. What size inverter do I need for a 3 bedroom flat?
And I understand why people ask it that way. It feels like a house size should have a matching system size, the way a room has a matching AC. But it does not work like that, and the people who answer it instantly are the ones you should be most careful of.
So let me give you the real answer, then show you how to get your own number in a day.
Why your flat size does not decide it
Two 3 bedroom flats on the same street can differ by several units a day. One runs two air conditioners, a deep freezer and a pumping machine. The other runs fans, a small fridge and lights.
Same flat. Same three bedrooms. Completely different system.
So when somebody quotes you off the shape of your house, they are not sizing anything. They are guessing, and the guess becomes your problem about four months later when the night stops reaching morning.
The two numbers that actually decide it
A system has two separate sizes, and people constantly confuse them.
The inverter is sized in kVA and it decides what you can run at once. It has to survive the surge, the gulp of power an AC compressor or a deep freezer pulls in the instant it starts, which is far more than it uses while running.
The battery is sized in kWh and it decides how long you can run. That comes from your daily usage, nothing else.
Get the battery right and the inverter wrong, and your AC trips the system every time it kicks in even with a full battery. Get the inverter right and the battery wrong, and everything works beautifully until 2am. Both failures look like a broken system to the person living in it.
What a 3 bedroom flat usually lands on
With that said, here is the honest range we see, so you have something to hold a quote against. Treat it as a starting point for a conversation, not a specification.
| What you run | Inverter | Battery |
|---|---|---|
| Lights, fans, TV, phones, small fridge | 1.5 to 2.5kVA | 3 to 5kWh |
| The above plus a deep freezer and a pumping machine | 3.5kVA | 5 to 8kWh |
| The above plus one AC in the evenings | 5kVA | 8 to 12kWh |
| The above plus two ACs, one running overnight | 7.5 to 10kVA | 15kWh and up |
Notice that the jump from the third row to the fourth roughly doubles everything. That single overnight AC is usually the most expensive decision in the whole system, and it is worth being honest with yourself about it. We went through that properly in can a solar inverter system power my air conditioner.
How to get your own number in one day
You do not need an engineer for this part, and you already own the tool. Your prepaid meter has been counting every unit your home burns, day and night, for as long as you have had it.
Read it tonight at a fixed time. Read it again at the same time tomorrow. Subtract. That difference is a day of your home’s power, in units, which are kWh. Do it across three ordinary days and average them if you can.
Then multiply your daily units by 2.2 and you have a rough lithium battery size. That is it. You now know more about sizing your home than the person who quoted you in two minutes.
The full method, with a printable worksheet, is in our free guide, what size inverter battery does my house need. It costs nothing and takes one day of paying attention.
What the meter reading cannot tell you
Three things sit outside your daily number, and it would be dishonest to pretend otherwise.
Surge, which is what sizes the inverter, and a meter cannot see it. Sunlight, because how much your roof actually catches decides whether panels can refill the battery in a grey week. And you, tomorrow, because people buy solar, stop worrying about fuel, and start using more.
A prepaid meter also only counts while NEPA is on, so on a poor supply street it undercounts. Treat it as a floor. A plug-in power meter fixes that, because it measures whatever flows through the socket whether the power came from NEPA or your generator.
What to ask before you pay anyone
Ask them to walk you through the sizing calculation rather than hand you a number. Then ask what happens if your usage grows in a year. Finally ask how they arrived at the inverter size specifically, and listen for the word surge.
A straight answer to all three means the system was designed. Vagueness on any of them means it was priced. There are more of these in questions to ask before paying, and our webinar on why solar disappoints people here shows what happens when nobody asks them.
Take the reading before anyone quotes you
Your flat does not have a size. Your load does. Take one meter reading, multiply by 2.2, and you are holding a number that a proper designer can work from and a guesser cannot argue with.
When you have it, send it to us on WhatsApp on +234 809 988 9885 along with what you want to run. We will size it around your actual home, and you get a straight answer whether you buy from us or not.