Solar Power - The Skinny Of It

Solar panels are available in a variety of sizes. The larger the panel size or area, the greater the electrical output. Common sizes range from 5W to 185W. The maximum output will only be achieved when the panel is pointing directly at the sun and the panel temperature is 25°C or less. Since our panel will be mounted horizontally, we will never quite see the full output as shown in the table below.

Angle of Sun to Panel% of Rated Output
90°100%
75°95%
45°75%
30°50%

As the table suggests, the actual output of your panels is dependent not only on the time of day, but on your latitude as well. For instance, the same panels in Cairns (latitude of 17°S) at midday will be producing around 90-95% of the panel’s maximum output. However, if you were to use these same panels in Hobart (latitude of 43°S), the performance at midday would decrease to around75% of maximum output. Of course, these figures are only approximated and depend on many factors, including the type of panel you’re actually using.

Also bear in mind that during the cooler months, the Sun’s zenith is lower in the sky (which yields a greater angle to the panel), and the days are much shorter which will result in approximately half as many Ah that can be collected during any given day.