# Watt-peak

The notion of watt-peak is used to compare the performance of photovoltaic solar installations and to predict the amount of electricity that can be produced under optimal conditions.

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

The objective of having the maximum power is to ensure that the power supply can handle peak loads and protect the power supply, thus preventing spikes from damaging the supply. For example, a 600 watt supply can have a maximum power of approximately 1200 watts for 5 seconds. Maximum power differs from one source to another and is usually specified in the data sheets of the power supply.

## Definition of 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).

Maximum power is the maximum power that the power supply can withstand for a short period of time and is sometimes referred to as peak power. Peak power differs from continuous power, which refers to the amount of power that the source can continuously supply. Maximum power is always higher than continuous power and is only required for a limited time.

A high-voltage power supply can provide enough power to drive all the components and achieve the expected 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.

## Watt-peak advantage

The watt peak allows a comparison between the outputs of the photovoltaic panels of 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 necessary size for a photovoltaic installation according to the performance sought.

Caution, the conditions of sunlight should also be taken into account in this calculation. A different output for 1 kWp of solar panels is achieved depending on the region where the photovoltaic installation is located and its sunlight conditions. Therefore, on the roof of his house in Brussels, a 1 kWp installation will produce 900 kWh per year in optimal conditions (south orientation, 35 ° angle). While on the roof of your holiday home in southern Europe, it will produce 1250 kWh / year!

## Definition of 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 engineer, inventor and constructor of Scottish instruments James Watt, for his contribution to the development of the steam engine, which was one of the triggers of the beginning 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 power unit, 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 of Weights and Measures, the same conference in which the AMP was included among others.

Last review: November 14, 2018