In the summer the solar irradiance and the temperature are high in comparison with the rest of the season, while the opposite occurs in the winter.
Do these meteorological changes nearly counter each other i.e. the energy production in the summer is almost the same as the winter?
Please answer based on your practical experience. Case studies will be appreciated.
I think it will depend on your geographical location. But I doubt that the energy obtained from a panel in Europe in winter would ever be higher than one at the same location in summer. The sun angle is too low. But it's an interesting question, though one with a lot of variables to allow for when trying to give a firm answer.
As Tony Maine says there are a lot of variables depending on geographic location. In the 12 years of operating the solar farm in Carnarvon Western Australia we have seen many variations in temperature and azimuth.
Our climate as to temperature is quite moderate mostly 25 - 30 degrees Celsius. You can work out the cell temperatures from there. We do get the odd 40 degree day and performance drops a fair bit.
A key variable is the type of panel. Some simply do better in the heat than others. Generally the lower the density of the panel the less temperature sensitive they are. For example the Sunpower (rear wired) 210W panels do not like the heat at all. The old GE 110W panels don't seem to be effected much at all. The Astronergy 270W loose a bit at the peak of the heat but pick up as soon as it gets cooler when the sea breeze comes in.
However the greatest single effect is simply duration. The summer days are longer so you harvest more. The cooler winter days are shorter and the sun is weaker. Also for summer our panels are south facing to compensate for the seasonal variation in azimuth.
The short answer is generally NO. Consider the extreme polar regions all harvest is in summer.
Thank you both for your feedback. I asked the question to make sure that the mentioned situation is general or not. I have long-term measurements of the outputs of a solar-PV power plant located at Egypt (one of the solar belt countries) composed of mixed technologies. The system is fixed at the latitude of the site and facing the south. These measurements show that the daily outputs in January's are nearly the same as in August. For sure the total solar radiation values in August is much higher than those of January. A situation that may indicates higher power output, but the readings show minor differences. The feasible explanation is the impact of the temperature, which counteracts the increase in the irradiance! The technologies are thin film CIS, and crystalline types. All of them show the same performances.
@Lex Fullarton,
I agree with your statement "However the greatest single effect is simply duration. The summer days are longer so you harvest more. The cooler winter days are shorter and the sun is weaker", but please note that my comment is based on a comparison between days in August, and days in January from the power (not the energy) point of view.
Generally, a rise in temperature increases the current of solar cells but reduces the voltage thus reducing its power eventually. This is why when solar panels are heated especially in summer days, a close observation of the power output will indicate a drop. It is quite funny though, most people would expect that high solar intensity should be advantageous to the cells but it isn't.
Yes, the problem is in the temperature caused reduction in the output power.
I think the energy yield may be match but the issue is there will be high fluctuations in cloudy days where the irradiance is purely diffuse also pay attention to the peak production may be occur in winter if the sky is clear and the tilt is at optimum
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