The peak power of a photovoltaic element is the maximum electrical power that it can generate under the following standard measurement conditions:

- Temperature: 20 degrees Celsius.
- Irradiance received: 1000 W / m²
- Air mass: 1.5

Air mass is a measure of the distance radiation travels through the atmosphere and varies according to the angle of incidence.

Irradiance is the power per unit area of incident electromagnetic radiation on a surface.

Peak power is the maximum power that the power supply can withstand for a short period of time. Peak power differs from continuous power, which refers to the amount of power that the source can supply continuously.

Maximum power is always higher than continuous power and is only required for a limited time.

## Why is peak power important?

The goal of maximum power is to **ensure that the power supply can handle the load spikes** and protect the power supply, thus preventing the spikes from damaging the supply.

**For example** , a 600 watt supply can have a maximum power of approximately 1200 watts for 5 seconds. The maximum power differs from one source to another and is generally specified in the data sheets of the power supply.

A high-voltage power supply will be able to provide enough power to power all components and accomplish the intended functions of the load or circuit. However, a power supply that is exactly 100% of the load capacity may not be sufficient due to losses and other factors that can affect the efficiency of the load.

## What is a watt-peak?

The maximum electrical power of a solar panel under these conditions is called peak power (Pmax) and is shown in Wp ( Watt-peak).

The notion of watt-peak is used to compare the performances of solar photovoltaic installations and to forecast the amount of electricity that they can produce under optimal conditions.

To compare the capacity of solar panels, there are established standard conditions: at an irradiance of 1 kW / m², the spectrum of which corresponds to the spectrum of sunlight in an air mass of 1.5 (this means that sunlight passing through the atmosphere is equal to one and a half times the average thickness of the atmosphere), and a cell temperature of 25 ° C.

### How useful is the watt-peak?

The peak of watts allows a comparison between the outputs of photovoltaic panels from different manufacturers. For the same surface area, the higher the Wp, the more efficient the panel will be.

The watt-peak is also used to calculate the size required for a photovoltaic installation according to the desired performance.

Sunlight conditions should also be taken into account in this calculation.

A different output is achieved for 1 kWp of solar panels depending on the region where the photovoltaic installation is located and its sunlight conditions.

Therefore, on the roof of a house in Brussels, a 1 kWp installation will produce 900 kWh a year in optimal conditions (south facing, 35 ° angle). The same installation in a house in southern Europe will produce 1,250 kWh / year.

## What is a watt?

The watt (symbol: W) is the power unit of the International System, it is the amount of energy in joules that is converted, used or dissipated in one second.

It is a derived power unit that takes its name from the Scottish engineer, inventor and instrument maker James Watt, for his contribution to the development of the steam engine, which was one of the triggers for the start of the Industrial Revolution.

The watt was adopted by the Second Congress of the British Association for the Advancement of Science in 1889, which meant its international recognition as a unit of power, incorporating it as an additional unit to the practical units defined in the CGS system. It was defined to the International System of Units in 1948 to the 9th General Conference on Weights and Measures, the same conference in which the ampere was incorporated, among others.