Guides · Faisalabad, Lahore, Punjab
kW vs kWh and Battery C-Rate Explained Simply
Short answer
kW (kilowatt) is power: how fast electricity is used or delivered at a moment. kWh (kilowatt-hour) is energy: how much is used or stored over time. One kWh is one "unit" on your electricity bill. A battery's kWh tells you how much it stores; its C-rate (such as 0.5C or 1C) tells you how fast it can safely deliver that energy. You need both to know whether a battery can run your house.
The water tank picture
Think of a water tank on your roof:
- kWh is the size of the tank. A 10 kWh battery holds twice as much energy as a 5 kWh one.
- kW is how wide the tap is opened. A 2 kW load draws energy twice as fast as a 1 kW load.
- Time links the two. Energy (kWh) = power (kW) × hours.
So a 1 kW load running for 5 hours uses 5 kWh. A 2.5 kW load running for 2 hours also uses 5 kWh.
kW, kWh and C-rate
kW = power
How much you can run at once
kWh = energy
How long it lasts
C-rate
Power ÷ capacity: 5 kW from 10 kWh = 0.5C
kW and kWh on your electricity bill
Your DISCO bills you in units, and one unit is one kWh. A bill of 600 units in a month means your house used 600 kWh. See how to read your electricity bill before going solar.
Your sanctioned load, by contrast, is in kW. It is the maximum power your connection is allowed to draw at one time, not the amount you use.
| Term | Unit | What it measures | Where you see it |
|---|---|---|---|
| Power | W, kW | Rate of use or supply right now | Appliance labels, inverter size, sanctioned load, solar system size |
| Energy | Wh, kWh, "units" | Amount used or stored over time | Electricity bill, battery capacity |
| Battery capacity | Ah (amp-hours) | Charge stored at a given voltage | Battery labels, often alongside kWh |
What a "5 kW lithium battery" usually means
Many people search for a "5kw lithium battery". Strictly, batteries store kWh, not kW. In Pakistani shops, "5 kW battery" nearly always means a battery that stores about 5 kWh. Our battery size calculator guide explains how to work out how many kWh you need.
The confusion matters because the kW figure for a battery is something different: how much power it can deliver at once. Two batteries with the same 5 kWh capacity can have different maximum output.
Converting Ah to kWh
Batteries are often labelled in amp-hours (Ah). To get kWh:
kWh = volts × amp-hours ÷ 1,000
For example, a 48 V class battery (51.2 V nominal for LiFePO4) rated at 100 Ah stores roughly:
- 51.2 × 100 ÷ 1,000 = about 5.1 kWh
The same 100 Ah at 24 V stores only about half as much energy. Always compare batteries in kWh, not Ah. See 24V vs 48V lithium battery.
What C-rate means
C-rate describes how fast a battery is charged or discharged compared with its capacity.
- 1C means a current that would fully charge or empty the battery in about 1 hour.
- 0.5C means a current that would do it in about 2 hours.
- 0.2C means about 5 hours.
For a quick power estimate, you can multiply the kWh capacity by the C-rate:
Maximum power (kW) ≈ capacity (kWh) × C-rate
| Battery capacity | At 0.5C | At 1C |
|---|---|---|
| 5 kWh | about 2.5 kW | about 5 kW |
| 10 kWh | about 5 kW | about 10 kW |
| 15 kWh | about 7.5 kW | about 15 kW |
Round illustrative numbers only. Real ratings come from each battery's datasheet, which may state continuous and short-term peak values in amps or kW.
The times are ideal. In practice, charging tapers near full, and the BMS may stop discharge early because of voltage, temperature or state-of-charge limits.
Why the C-rate matters for your home
Suppose, for example, you have a single 5 kWh battery rated at 0.5C, so roughly 2.5 kW of continuous output. At night, during load-shedding, you switch on:
- a 1.5 ton inverter AC drawing, for example, 1,400 W;
- fans and lights at 400 W;
- a fridge at 200 W;
- a water pump starting up at 1,000 W.
That adds up to about 3 kW. The battery has enough energy for a while, but not enough power for everything at once. The likely result is an overload warning or the battery's BMS cutting off. See battery BMS explained.
Fixes include a battery with a higher C-rate, a second battery module (two 0.5C 5 kWh modules in parallel give roughly 5 kW), or not running the pump and AC together. Our solar for AC guide helps with AC loads.
The inverter has a kW limit too
The battery is only half the story. The inverter has its own continuous output rating (kW), a short surge rating, and a maximum battery charge and discharge current. The usable power is the lowest of the battery limit and the inverter limit. A 6 kW inverter on a battery that can deliver only 2.5 kW will be limited by the battery when the sun is down. For inverter sizes, see solar inverter prices.
Does a higher C-rate mean a better battery?
Not automatically. A higher rating means the battery can deliver more power, which is useful for heavy loads. But running any battery hard all the time produces more heat, and heat speeds up ageing. For most homes, a battery that runs well inside its rating most of the night is the healthier choice. See how long lithium solar batteries last.
Solar panels: kW and kWh again
The same units apply to panels. A "10 kW solar system" means about 10 kW of panel power under test conditions. How many kWh (units) it produces depends on sunlight hours, season, heat, dust and shading. See how many solar panels for a 5 kW or 10 kW system. We never promise a fixed number of units; a design gives an estimate with stated assumptions.
Ask us to check your numbers
Solar Works Pakistan sizes battery capacity (kWh) and power (kW) from your actual night-time and load-shedding loads, then matches a Luminey and current Huawei and Sungrow options battery to a compatible inverter. For options, see lithium battery prices.
Get today's price or a free site survey
- WhatsApp or call: 0336 666 4321
- Email: info@solarworks.pk
- Head office: Main Boulevard, Sargodha Rd, Block F FDA City, Faisalabad
- Lahore branch: 2nd Floor, Jeff Heights, Gulberg, Lahore
- Hours: 9:00 AM to 6:00 PM daily
We serve all of Punjab, and site surveys are normally free. Contact us.
Frequently asked questions
What is the difference between kW and kWh?
kW measures power, the rate at which electricity is used or supplied at a moment. kWh measures energy, the total used or stored over time. Running 1 kW for 1 hour uses 1 kWh.
Is one unit of electricity 1 kWh?
Yes. One unit on a Pakistani electricity bill is one kilowatt-hour. A 100-unit bill means about 100 kWh were used that month.
What does 0.5C mean on a battery?
It means the battery is rated to charge or discharge at a current that would take about two hours to fill or empty it. A 10 kWh battery at 0.5C can deliver roughly 5 kW, in round numbers.
What is a 5 kW lithium battery?
In everyday use it usually means a battery that stores about 5 kWh. Its power output depends on its C-rate and the inverter, so check the datasheet's continuous discharge rating too.
How do I convert Ah to kWh?
Multiply volts by amp-hours and divide by 1,000. A 51.2 V, 100 Ah battery stores about 5.1 kWh.
Can a 5 kWh battery run a 5 kW load?
Only if its C-rate allows about 1C and the inverter can supply 5 kW, and then only for roughly an hour. Many home batteries are rated lower, so heavy loads may need a second module.
Is a 1C battery better than a 0.5C battery?
It can deliver more power, which helps with heavy loads. It is not automatically longer-lasting. Choose the rating that matches your peak load with some margin.
Sources
- SurgePV glossary, "C-rate" (definition, 1C and 0.5C examples, kW/kWh ratio caveats)