What is nominal operating cell temperature?

The nominal operating cell temperature (NOCT) is the major of the factors that have an impact on the solar panel performance and should be taken into consideration during the optimization of any solar power system.

Sure enough, it has an effect on the photovoltaic power generation.

nominal-operating-cell-temperature What is nominal operating cell temperature? News

The nominal operating cell temperature (NOCT) is defined as the solar panel temperature based on four main standard reference environment:

  • Irradiation on the solar panel = 800W/m2.
  • Wind velocity = 1 m/s.
  • Air temperature = 20°C.
  • Inclination angle (open rack mounted) = 45° from the horizontal.
nominal-operating-cell-temperature-1 What is nominal operating cell temperature? News

The operating cell temperature is the difference between the temperature produced by the solar panel while working and the temperature losses to the environment through the three mechanisms of heat transfer: the conduction, the convection and the irradiation.

Each type of the solar panels has a different operating temperature, based on two main factors:

  • The solar panel design.
  • The mounting conditions.

According to the thermodynamic theories, the NOCT of any Photovoltaic power system increases and decreases regarding the surrounding circumstances.

Obviously, the temperature during the night is lower than the day and the solar panel works only in the sunshine.
Normally, the temperature of the solar panel during the night is equal to the ambient temperature however within the day it will be much higher regarding the operating cell temperature.

Night-and-Day-Temperature-3 What is nominal operating cell temperature? News

It is important to determine and understand this to identify the solar panel performance over its lifespan.

Noct-Amerisolar What is nominal operating cell temperature? News
Sources: pveducation.org

The following graph expresses the heat transfer through conduction & convection between the solar panel and the ambient temperature in presence of a certain wind speed.

It shows the best NOCT (nominal operating temperature) in blue and the worst NOCT in red and the moderate one in black. You can obtain the best NOCT thanks to the aluminium material at the rear of the solar panel that reduces the thermal resistance and increases the surface area for the convection.

The formula that shows you how to calculate the nominal operating cell temperature is the following one:

Tsolar panel=Tambient +((NOCT-20)/80)*S While S is the insolation in mW/cm2.

We can categorize the solar panels according to their efficiency based on the nominal operating cell temperature:

  • The lowest efficiency operates at NOCT 33°C.
  • The moderate efficiency operates at NOCT 48°C.
  • The highest efficiency operates at NOCT 58°C.

Obviously, the temperature during the night is lower than the day and the solar panel works only in the sunshine.

Normally, the temperature of the solar panel during the night is equal to the ambient temperature however within the day it will be much higher regarding the operating cell temperature.

nominal-operating-cell-temperature-solar-panel What is nominal operating cell temperature? News

What are the practical benefits from
the determination of the nominal operating cell temperature?

By estimating the previous parameters in a reliable way you can:

  • Compare the performance of different solar panels’ designs.
  • Predict the solar panels performance.
  • Predict the solar panels output power generation.

You can find Amerisolar NOCT parameter in our data sheets.

By |2018-06-19T09:45:59+00:00June 15th, 2018|News|Comments Off on What is nominal operating cell temperature?