Is there an optimum temperature beyond which PV electricity production will decrease and what are the measures to be taken to take care of this in order to avoid power drop during high ambient summer temperatures in tropical area where temperatures may reach as high as 49oC.
For most PV technologies the break even temperature will be very low, well below 0C, so any increase in temperature beyond this will cause an increase in the internal shunt current and reduce the PV output. In tropical conditions PV will always generate less output than in temperate climates. You might consider putting IR reflective material on the panels, that won't change the effect of ambient temperature but it will decrease the effect of IR absorption of the panel which will make the panel (slightly) cooler. Whether it's worth doing needs a more detailed calculation! Best wishes.
Solar panels work best under certain weather conditions, but since the weather is always changing and as engineers are installing solar panels all over the world in different climate regions, most panels do not operating under ideal conditions. That is why it is important for engineers to understand how panels react to different weather conditions.
when the temperature increases the generated power from the PV array decreases. See the results of the attached paper.
Temperature can affect how electricity flows through an electrical circuit by changing the speed at which the electrons travel. The PV system must be engineered not only according to the maximum, minimum and average environmental temperatures at each location, but also with an understanding of the materials used in the PV panel. The temperature dependence of a material is described with a temperature coefficient. For polycrystalline PV panels, if the temperature decreases by one degree Celsius, the voltage increases by 0.12 V so the temperature coefficient is 0.12 V/C.
The temperature of PV panel will affect the efficiency of the PV panel. Ambient temperature will affect the passive cooling of the PV panel that will lead to the decreasing of efficiency. To avoid high temperature of PV panel then you can use either better passive cooling system or active cooling system. An example of a passive cooling system is by using a heat sink (thermal fins) and an example of active cooling is by using water (hybrid PV-thermal). There are many references relate with this, you can googling it. Hope this can help. Regards.
Thank you all for your answers.
What about if we use partial shading of the sun? Will that be effective to cut down the high temperature? and by the way what is the maximum endurable temperature beyond which PV power will drop dramatically?
I think the best way is to cool PV moduls by water flow in your case. It is good to cooperate with mehanical engineer. As a result you could have hot water for domestic needs.
Usually, NOCT (nominal temperaure of the cell) is not more then 25 degrres C, enviroment temperature of 20 degrees C, sun iradiation 0,8 kW/m2 and wind speed 1 m/s.
All nominal data of PV modul given by manufacturer is usually like that. Maybe, there are some diferences but it should be like that.
Besides, junction temperature is typically higher than air temperature. Because PV panels haven't 100% efficiency, the part of input solar energy that is not converted into electrical power, must flow thermally to the ambient air. Under STD conditions (1000W/m2), you can expect Tj to be 50° higher than Tamb, thus typically 75°C. This may become a bit hasardous when Tamb gets as high as 50°C, as Tj may extend 100°C.
Under constant irradiance, power delivered by PV cells is affected by temperature in 2 ways.
- First, Voc,Vmp naturally decrease, since ratio Vbr/kB*Tj decreases.
- Second, Isc,Imp increase with temperature, the junction being thermally activated.
- Finally, how much MPP power is affected depends on the junction technology. Most cells have negative temperature coefficient (Voc reduces more than Isc increases), but some cells have positive coefficient (Voc reduces less than Isc increases).
Dear Kamal: the increase of temperature of PV reflected negatively on the electrical power productivity. When the temperature increase the current increase insignificantly but the voltage decrease significantly and lead to reduce the power and efficiency. However, some research mentioned that for each 1 oC (behind the 25 oC) increase in temperature, 0.3-0.4 V decrease occurred in the PV voltage. One of the most promising ways to reduce the PV temperature is to use PV/T (hybrid PV/Thermal) system. Some nano fluids used in these systems shows a significant reduction in temperature and improvement the PV efficiency. I advise you to see the project in my page.
If you use PV/T then get the thermal absorber to remove all the IR from the light before it reaches the PV. Then the PV will heat up less.
Dear Professor Kamal,
Please check the attached article, I hope it will be useful.
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