In the fields of energy storage and new energy, we often hear units like Wh, kWh, MWh, and GWh. What do they represent? If converted to the common 18650 battery cell, how many cells are there? This article will guide you through understanding.
Basic Unit: Energy of a Battery Cell (Wh)
First, we need to understand the most basic unit of energy—watt-hour (Wh). Let’s take a common 18650 ternary lithium battery cell (nominal voltage 3.7V, capacity 3000mAh) as an example:
Calculation Formula: Energy (Wh) = Voltage (V) × Capacity (Ah)
Conversion Relationship: 3000mAh = 3Ah
Result: Energy of a single battery cell = 3.7V × 3Ah = 11.1Wh
Real-life Example:
5 battery cells: Approximately 55.5Wh, commonly found in high-powered power tool battery packs.
90 battery cells: Approximately 1000Wh, or 1kWh (1 unit of electricity), commonly found in electric scooters.
A Leap of Order of Magnitude: From 1 Unit of Electricity to 1 GWh
When battery cells are grouped together, the energy unit undergoes a leap of “order of magnitude”:
1 kWh (1 unit of electricity) = 1000 Wh
Number of cells: Approximately 90 18650 cells.
Size: Approximately the size of a shoebox.
What it can do: Power a 1-horsepower air conditioner for 1 hour, or light a 10W LED light for 100 hours.
1 MWh (1 megawatt-hour) = 1000 kWh
Number of cells: Approximately 90,000 18650 cells.
Size: Equivalent to the volume of a 20-foot shipping container.
1 GWh (1 gigawatt-hour) = 1000 MWh
Number of cells: Approximately 90 million 18650 cells.
Size in comparison: Equivalent to a giant energy storage power station composed of 100 20-foot shipping containers.
Energy Conversion to Cells in Real-World Scenarios
The scale of energy storage systems varies greatly depending on different application requirements:
| Application Scenarios | Typical Capacity | Equivalent Number of 18650 Cells | Volume/Scale Diagram |
|---|---|---|---|
| Residential Energy Storage | 10 kWh | Approximately 900 cells | Approximately the size of one refrigerator |
| Commercial and Industrial Energy Storage | 200 kWh | Approximately 18,000 cells | Approximately one standard cabinet (0.5m³) |
| Grid-Side Energy Storage | 2.5 MWh | Approximately 225,000 cells | One 20-foot container |
| Large-Scale Energy Storage Power Station | 100 MWh | Approximately 9 million cells | Approximately 100 20-foot containers |
Core Conclusion
1 kWh (kWh) = Approximately 90 18650 cells.
Energy storage equipment (such as containerized power plants) is typically measured in MWh, while national/global-scale installed capacity is measured in GWh.
Special Note: The above conversions are based on a single 11.1Wh 18650 cell. In actual systems, cells need to be combined in series and parallel, and a BMS (Battery Management System) and structural components are added, resulting in approximately 10% system capacity loss. Group efficiency must be considered in the calculations.