Quantifying waste heat energy absorbed by a solar array involves measuring the difference between the incoming solar radiation and the converted electrical energy. This can be done using thermographic imaging, temperature sensors, and performance monitoring systems to assess heat dissipation. Analyzing these factors helps estimate the efficiency of the solar array and identify areas for optimization.

The conversion efficiency of PV cells is roughly 20%. Hence 80% of the incident solar radiation is either reflected or converted into heat. Since the reflection coefficient of these cells is rather low, more than 70% becomes heat.

When a cell is damaged and does not produce electricity or produces less, it generates more heat and becomes warmer. This allows detecting the damaged cells with thermographic imaging.

To quantify this thermal energy generated by a photovoltaic solar panel despite the electrical energy in energy terms, we can use the following formula:

Thermal energy generated = Thermal power × Time

With :

-Thermal power which and is the amount of heat generated by the solar panel per unit of time, time is the length of time the heat is generated by the panel.

where Thermal Power = Heat Loss Factor × Illuminance × Panel Area

Here, the Heat Loss Factor is a value between 0 and 1 that represents the proportion of incident solar energy converted into heat. This proportion depends on the efficiency of the solar panel and the environmental conditions.

Illuminance is the amount of solar radiation incident on the solar panel. It is expressed in watts per square metre (W/m²). Solar irradiance data can be obtained from a local weather station or online.

So, once you've calculated the thermal power and the time, you simply multiply them to get the total thermal energy generated by the solar panel.

Case study:

Suppose you have a photovoltaic solar panel with a heat loss factor of 0.50, it receives 1000 W/m² irradiance and has a surface area of 4 m². If the panel were to operate for one day (24 hours), the thermal energy generated would be :

Thermal energy = (0.50 × 1000 W/m² × 4 m²) × 24h = 48000 Wh

It should also be noted that this value is a rough estimate and that the actual thermal energy generated by a solar panel can vary depending on various factors, such as ambient temperature, wind speed and panel orientation.