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Data of a photovoltaic system concerning the cloud cover of the sky – Climate detectives
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Climate change

Data of a photovoltaic system concerning the cloud cover of the sky

Date : 31/05/2019
School name : Hellenstein-Gymnasium
Student's age : 12-13
Number of team members : 31
Summary of the project : According to online climate tables the following average climate data for Heidenheim are documented per example for the months of June – September: • 7 – 8 hours of sunshine per day • 13 – 16 days of rain Source: We have observed that there was a clear surplus of hours of sunshine per day during the past summers whereas the number of rainy days differed strongly from the average values found in the climate table for Heidenheim. On the foundation of these findings we assume a connection with climate change. Since some years Hellenstein Secondary School has had a photovoltaic system installed on its roof whose data students will analyze in the context of this project. The performance of the system can provide information about sunshine and cloud cover. Data can be compared and analyzed. The effects of the clouds on the weather are very big. On the one hand they prevent the radiation of the heat of the earth and on the other hand they reflect the incident solar radiation. Heating the air leads to an increased absorption of moisture and thus probably to more clouds. Source:
Main results : We evaluated the data from the photovoltaic system and specified the cloud cover in one to eight eighths. You can see the evaluated data in our diagram beginning in june 2012 and ending in march 2017. We tried to see some tendencies but of course this is very difficult and with only 5 years of data no proof at all! Nevertheless there seem to be two opposite developments visible: 1) Less clouds in the cold months: Very obvious in january where the cloud covering decreases from year to year, this tendency is maybe also visible in february and march but not in december (where it is still not too cold in Heidenheim). 2) More clouds in the warm months: Especially in juni, september and october but not visible in july and august. 3) Between these opposite developments the cloud covering is more or less quite stable in april, may, november and december. We know that so far we have only evaluated weather data and no climate data. We will continue our investigation in the future to get more valid data.
Actions to help lessen the problem : As a school, we will try to produce less CO2 and save energy in the building to become more sustainable. We select energy managers, who make sure that the breaks are correctly ventilated, after class all windows are closed and the lights are off. They also control the correct setting of the thermostatic valves. Our students go on a search and create an overview of the stand-by consumers. Then it will be decided how to save electricity.
Location :Heidenheim

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