When I first started dealing with inverter specs, I often saw two values—kW and kVA. At first, they seemed interchangeable. But later I realized they mean very different things, and understanding the difference is essential when selecting an inverter for solar and battery storage systems.
kW (kilowatts) measures real power—what actually powers your appliances. kVA (kilovolt-amps) measures apparent power—the total power the inverter handles, including both useful and reactive power. The gap between the two can affect system performance and sizing.
Let’s break this down so you know exactly what you’re choosing when picking an inverter.
What do kW and kVA mean in inverter specifications?
kW refers to the real or usable power output of an inverter. kVA represents the total power capacity it can carry, including power lost in phase difference (reactive power).
Key Definitions
| Term | Meaning | Unit |
|---|---|---|
| kW | Real power (usable) | Kilowatts |
| kVA | Apparent power (total capacity) | Kilovolt-Amps |
| Power Factor | Ratio of kW to kVA | (usually 0.8–1.0) |
For example, an inverter rated at 10 kVA with a power factor of 0.8 can only deliver 8 kW of real power. That means if your total appliance load is 10 kW, this inverter will not be enough.
Why is power factor important when choosing an inverter?
Most hybrid and solar inverters operate at a power factor between 0.8 and 1.0. The power factor directly impacts how much usable energy (kW) you can get from your inverter.
If your inverter has a power factor of 0.9, then a 10 kVA inverter will deliver only 9 kW of real output.
Example Calculation
Let’s say you have a 12 kVA inverter with a power factor of 0.85:
Real Output (kW) = 12 kVA × 0.85 = 10.2 kW
This means the inverter can only handle 10.2 kW of actual load—not 12.
Why This Matters
- Sizing errors can lead to underperformance
- Battery mismatch may cause inefficient energy storage
- System overloads reduce inverter lifespan
Understanding this gap helps avoid overspending on capacity or overloading your system.
How does this apply to solar and hybrid inverter systems?
In PV systems, especially those with lithium battery integration, accurate power ratings are critical.
Inverters must handle peak solar input, battery charging, and load output—all at once. Choosing an inverter rated in kW (not just kVA) gives you a clearer view of real usable power.
At SANKE, we always recommend:
- Confirming inverter power factor before purchase
- Matching inverter kW rating to total household or commercial load
- Accounting for battery charge/discharge power in the design
This prevents undersizing and keeps your solar-storage system running efficiently.
How to choose between a kW and kVA-rated inverter?
Choose inverters with clear power factor information and look at the kW output, especially in hybrid or off-grid systems.
Always design your load around the kW capacity, not just kVA.
| Application | Focus On | Why |
|---|---|---|
| Residential | kW (real power) | Appliances need usable power |
| Commercial/Industrial | kVA + PF clarity | Larger loads with reactive power |
| Off-grid + batteries | kW output + surge | Must handle peak loads safely |
Conclusion
Knowing the difference between kW and kVA prevents common inverter sizing mistakes. For solar or hybrid applications, always ask about the power factor and real kW output. It makes your energy system safer, more efficient, and longer-lasting.
At SANKE, we provide full-range solar and hybrid inverters with clearly rated kW output, high power factor, and lithium battery compatibility. Our engineering team helps every client choose the right solution—no guesswork involved.
FAQs
What is the difference between kW and kVA?
kW is real usable power; kVA is total apparent power. The difference depends on power factor, which accounts for losses in the system. A 10 kVA inverter may only deliver 8 or 9 kW.
Why is power factor important in inverters?
Power factor tells you how much of the inverter's rated power is usable. A lower power factor means more losses. Choosing an inverter with a high power factor ensures better efficiency and real output.
Can I use a 10 kVA inverter for a 10 kW load?
Not necessarily. If the inverter’s power factor is less than 1, it won’t deliver the full 10 kW. You need to check both kVA and the power factor to confirm actual usable output.
What should I look for when buying a hybrid inverter?
Check for real power output (kW), power factor, number of MPPTs, battery compatibility, and rated efficiency. Don’t choose based on kVA alone—look at what the inverter can actually deliver to your load.
