We explain the performance curve of our PVTs!
In today’s post, we are going to explain the different performance curves of a hybrid panel or PVT.
The operation of a hybrid panel is different from other types of generation equipment that we can find in the market, such as a gas boiler. In the case of a PVT, energy production will depend on several factors and conditions. The sun, the ambient temperature and the temperatures of the fluid circulating inside the panel will determine the energy that the panel is capable of producing.
To determine the instantaneous operation of the panel, it is necessary to obtain its performance at that instant, which will allow us to calculate its power. A hybrid panel has three performance curves: photovoltaic, thermal and total. The total efficiency is the sum of both efficiencies. The following figure shows each of the three.
The curves have been calculated according to 9806:2017 where the vertical axis is defined as the performance and the horizontal axis as (Tm-Ta/G), sometimes also denoted as G*. Where Tm (°C) refers to the average panel temperature, which can be roughly calculated as the average of the inlet and outlet temperature of the fluid in the panel. Ta (°C) is the ambient temperature and G (W/m²) is the incident irradiance on the panel surface.
If the panel temperature (Tm) is higher than the ambient temperature (Ta), thermal losses occur in the panel. In order to calculate the efficiency of the panel in such cases, it is necessary to refer to the thermal efficiency curve of the panel:
ƞ=ƞ0 – a1*G* – a2 * G*².
In the Abora hybrid panel, the optical efficiency (ƞ_0) is 0.7, the thermal loss coefficient a1 is 5.98 W/m²K and the thermal loss coefficient a_2 is 0 W/m²K². The null term a2 makes the thermal performance curve a constant slope straight line, which is not the case for other thermal collectors.
To better understand the curves, a hypothetical case is considered. Standard test conditions (STC) are considered, where the irradiation is 1000 W/m², and the panel temperature coincides with the ambient temperature (Tm = Ta). This results in a value of G* equal to 0 and, using the curves in the graph (in red), a thermal efficiency of 70% and an electrical efficiency of 17.8% is obtained. As the irradiation considered is 1000 W/m² and the total area of the panel is 1.96 m², only by multiplying these three values we obtain the thermal and electrical power of the panel. These would be 1372 W thermal (0.7*1000*1.96) and 350 W electrical (0.178*1000*1.96), making a total power of 1722 W approximately.
In a situation other than STC conditions, the calculation procedure is identical. It starts by calculating the value of G* from the mean fluid temperature (Tm), the ambient temperature (Ta) and the irradiation (G). Then, the efficiency curves are searched for the point that intersects with the vertical of this value on the horizontal axis (G*), obtaining the thermal, electrical and total efficiencies under the established conditions. Multiplying by the irradiation and the surface area of the panel (1.96 m²), we finally obtain the power of the panel under these conditions. The following figure shows a case in which the irradiation is 800 W/m², the average panel temperature is 46 °C and the ambient temperature is 30 °C. This results in a G* value of 0.02, which following the vertical results in a thermal efficiency of approximately 57 % and an electrical efficiency of 16.5 %. The thermal power will therefore be 893.76 W, the electrical power 258.72 W and the total power 1152.48 W.
As can be seen, obtaining the yields of the Abora hybrid panel from the yield curve graph is very simple. It is only necessary to know the operating conditions and follow a few simple steps.
If you have any doubts, please contact us and we will be delighted to help you.
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Do you know that…
Did you know that heat is a form of energy that passes from hot to cold objects? This process is called heat transfer. There are three main modes of heat transfer:
1. Conduction: Heat travels through a solid material or between two objects in direct contact. For example, when you touch a hot pan, heat is transferred to your hand by conduction. 2. Convection: Heat moves through a fluid (liquid or gas). This usually occurs by the movement of a hot fluid rising and a cold fluid falling, as in convection currents in a pot of boiling water. 3. Radiation: Heat travels as electromagnetic radiation through space. This is how heat from the Sun reaches the Earth, even over very large distances.
Heat transfer is a fundamental concept in thermodynamics and plays a crucial role in many natural and technological processes in our daily lives.
abora, what is it?
Abora Solar, a Spanish manufacturer of hybrid solar panels, is an innovative and visionary company in the field of renewable energies, more specifically in the solar energy sector. Founded in 2017, the Spanish manufacturer has quickly positioned itself as a major player in the development of sustainable and high-performance solar solutions.
At the heart of Abora Solar’s identity is a global approach to solar energy, offering the latest generation hybrid solar panel with the highest performance on the market, while providing a vision that encompasses the entire process, from design to manufacturing, including the monitoring of installations. This allows the company to offer its customers turnkey solutions for projects in industrial, tertiary and residential buildings.
In short, Abora Solar embodies the future of solar energy, combining technological innovation with a deep commitment to the environment, accessibility and the improvement of society. The company is a major player in the energy transition towards a cleaner and more sustainable future.
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