Quick answer: Choose an inverter by matching its kVA rating to your peak load (everything that could realistically run at once, plus a safety margin) — not your total energy use. For most homes, that means a 3.5–5kVA hybrid inverter. Larger homes and small businesses typically need 8–10kVA. Here's how to work out which one is yours.
The inverter is the decision-maker, not just a converter
It's easy to think of the inverter as a simple box that "changes solar into usable power." In a hybrid system, it's doing much more than that — it's constantly deciding whether to draw from solar, battery or grid, how fast to charge the battery, and what to do the instant the grid drops. Get the inverter sizing wrong, and even a well-designed solar and battery setup underperforms.
Power (kW/kVA) vs. energy (kWh) — the distinction that matters most
This is the single most common confusion we clear up during assessments. An inverter's rating in kVA describes how much power it can deliver at any one instant — think of it as the width of a tap. Your battery's kWh rating describes how much energy it can store and deliver over time — the size of the tank.
A 5kVA inverter can deliver up to 5,000 watts at once. If you switch on a 900W air conditioner, a 1,000W microwave, a fridge and some lights simultaneously, you could be close to that ceiling — even though your battery might have plenty of energy left for the day.
Step 1: Add up your peak load, not your total
List every appliance you might run at the same time (not everything you own) and sum their wattages:
| Appliance | Typical watts |
|---|---|
| Split AC (1HP) | 900W |
| Refrigerator | 150W (higher at start-up) |
| 4 fans | 280W |
| TV | 120W |
| Lights (8 bulbs) | 80W |
| Peak total | ≈1,530W |
Step 2: Add a safety margin for motor start-up
Anything with a compressor or motor — fridges, freezers, pumps, AC units — draws a short burst of extra power when it starts, often 2–3 times its running wattage. Inverters need headroom to absorb this without tripping. A standard rule we use is to size the inverter at roughly 1.3x your calculated peak load.
For the example above: 1,530W × 1.3 ≈ 1,990W, which rounds up comfortably to a 3.5kVA inverter — the smallest size we typically install, and enough headroom for future appliances.
Step 3: Match the inverter to your battery and solar array
An inverter is only as useful as what it's connected to. Two numbers to check on any inverter's spec sheet:
- Battery input compatibility — make sure it supports lithium (LiFePO₄), not just lead-acid, if that's the battery chemistry you're installing.
- Solar input (kW) — this caps how much solar array the inverter can accept. A 5kVA inverter paired with a 6kW solar input, for instance, lets you add more panels later without replacing the inverter.
Our comparison table below shows how this scales:
| Inverter size | Capacity | Battery input | Solar input | Typical fit |
|---|---|---|---|---|
| Entry | 3.5 kVA | Lithium | 4 kW | Small flat or starter home |
| Standard | 5 kVA | Lithium | 6 kW | Most homes |
| Large | 8 kVA | Lithium | 10 kW | Larger homes, small offices |
| Premium | 10 kVA | Lithium | 12 kW | SMEs, clinics, small hotels |
| Commercial / 3-phase | 12 kVA, 3-phase | Lithium | 15 kW | Industrial and 3-phase sites |
Single-phase or three-phase?
Most Nigerian homes run on single-phase power, and single-phase hybrid inverters up to 10–12kVA cover the vast majority of residential and small commercial needs. Once a site has heavier motor loads — boreholes, industrial equipment, large HVAC — or is already wired for three-phase supply, a three-phase inverter keeps the load balanced across all three phases rather than overloading one.
Don't forget: warranty and local support
A technically perfect inverter is a poor choice if nobody nearby can service it. Before choosing, check the manufacturer warranty length (5–10 years is standard on the units we install) and confirm that spare parts and technical support are available locally — not just from an overseas supplier.
The one number worth double-checking
If you only check one thing before buying, check that the inverter's continuous rating (not its brief "surge" rating) comfortably covers your calculated peak load. Surge ratings look impressive on a spec sheet but only apply for a few seconds — your continuous load is what matters for day-to-day running.
FAQs
Can I undersize the inverter to save money?
You can, but the system will trip or shed load whenever you exceed its peak rating — usually the exact moment you need it most. It's the one component we don't recommend cutting corners on.
Does a bigger inverter use more power when idle?
Slightly, but the difference is minor compared to the cost of a system that can't handle your actual peak load.
Will my existing generator work alongside a new inverter?
In most cases, yes — many of our systems are designed so the generator remains available as a backup-to-the-backup, feeding into the same hybrid inverter.