Wp (Watt Peak)

What Does Wp Mean?

Wp (Watt Peak) is the unit for the peak electrical power of a solar module under Standard Test Conditions (STC). A module rated at 400 Wp delivers a maximum power of 400 watts under laboratory conditions (1,000 W/m² irradiance, 25 °C cell temperature).

Relationship with kWp

Unit	Conversion	Typical Use
Wp	1 Wp	Single module
kWp	1,000 Wp	Entire system
MWp	1,000,000 Wp	Large solar parks
GWp	1,000,000,000 Wp	National statistics

Current Module Power Ratings

Modern solar modules achieve the following typical Wp values:

• Standard module (approx. 1.7 x 1.1 m): 400—450 Wp
• High-performance module: 450—500 Wp
• Balcony solar system module: 380—450 Wp
• Small module (garden/camping): 100—200 Wp

Practical Tip

The Wp rating enables direct power comparison of different modules. For yield calculations, however, the site-specific kWh yield per kWp is decisive, as real-world performance depends on many factors.