kWp (kilowatt-peak) is a measure of the rated power of solar systems, indicating the maximum energy generation capacity that a solar panel or solar system can achieve under standard test conditions (STC) .
What does kWp mean?
Maximum power: Shows the highest power that a solar system can produce under optimal conditions.
Standard Test Conditions (STC):
- Temperature: 25 °C (solar cell temperature).
- Irradiance level: 1000 W/m² (sunlight intensity).
- Atmospheric mass: AM1.5 (spectral distribution of solar radiation).
Physical capacity: A solar system with a power of 1 kWp means that it can produce 1 kWh of energy in one hour under optimal conditions.
Why is kWp important?
Determining system size: kWp helps determine how large a solar system is needed to meet a given energy demand.
Energy yield estimation: Based on kWp, the annual energy production of the system can be calculated, taking into account the given geographical location and hours of sunshine.
Installation planning: By taking kWp into account, it is possible to determine how much area is required to install solar panels.
How is the kWp value calculated?
The kWp value depends on the number, efficiency and size of the solar cells. Example:
- Power of a solar module: 300 Wp.
- A system consists of 10 such modules:
- 300 Wp × 10 modules = 3000 Wp = 3 kWp.
Example of a kWp-based calculation
Installing a 5 kWp system in Hungary:
- The number of annual sunshine hours is 1200 hours.
- Estimated annual energy production:
- 5 kWp × 1200 hours = 6000 kWh.
Energy demand estimation: If a household's annual energy consumption is 4,500 kWh, a 4-5 kWp system may be able to cover this demand.
kWp vs. kW
| Property | kWp | kW |
|---|---|---|
| Report | Rated power under optimal conditions | Current device performance during operation |
| Application | Measuring the capacity of solar systems | General performance measurement |
| Conditions | Standard Test Conditions (STC) | Real environmental conditions |
Summary
Kilowatt-peak (kWp) is a standard unit of measurement for the power and capacity of solar PV systems, which helps in system sizing and estimating potential energy yield. Although kWp indicates optimal conditions, actual performance depends on many factors. Accurate knowledge of kWp is essential for the efficient design and installation of solar PV systems.