In Australia, over 20% of households have solar panels installed. Although solar technology is making vast improvements in performance efficiency; the efficiency level is still between 11 -22%. This means that only 22% of the Sun’s energy is converted into electrical energy.
A solar panel collects sunlight and converts it into electrical energy. There are a few reasons why efficiency can be lower on any particular day. Weather and seasonal factors cause the most variation in how much energy output you will receive in a day.
The length of day is the major contributor to how much sunlight a panel will receive, and therefore how much energy it can produce. In Australia, there is not much variation between the length of day in winter and summer (only about 2.5 hours). However, the further away you are from the equator the greater the difference will be. For example, in Iceland it doesn’t get dark at all in their summer compared to winter where there are only a few hours of sunlight. Even with a battery, there would not be enough solar energy generated in winter to be relied upon as a sole energy source.
Latitude_and_longitude, accessed 30/4/2020
The amount of light the panel receives is also an important factor. There are a few reasons this can vary throughout the day. One major consideration is the angle that the solar panel is placed at and its position on the building. Solar panels are installed to ensure they capture the maximum sunlight for their geographic location. The angle of the panels will be different, adjusted for latitude.
Eyafjallajokull, accessed 30/4/2020
The weather is also a key contributor to the efficiency of a solar panel. The clearer the sky, the more light a solar panel will receive. This means that a cloudy day will greatly reduce the amount of energy the panel receives and produces.
A common misconception is that temperature effects the efficiency of a solar panel. It seems natural to think that on a hot, sunny day you will be getting optimal output from your solar panels. However, as the temperature rises the efficiency decreases. This is because the wires in the panels heat up, making the atoms in it vibrate more. This makes it harder for the electrons, which provide the electrical energy, to pass through. In simple terms, as the temperature increases the resistance also increases, making the panels less efficient. This means a clear day in winter may generate more electricity than a hot day in summer!
- Try this experiment to see if your results agree.
- Investigate how electricity flows with this simulation.