Many people ask how local climate affects efficiency of solar panels. Each type of panel built is rated for its efficiency against data showing the average house in an average neighborhood. Several factors can cause variations from this though, depending on local conditions.
The main thing affecting the efficiency is the distance the panels are north or south of the equator. Because the sun is is a different position in the sky relative to places on earth according to their latitude, the amount of solar radiation which a panel receives varies considerably. It is the solar radiation that provides most of the energy collected by solar panels.
Properties nearer the equator get a much greater amount of solar radiation than those in the higher latitudes. To compensate for this different types of solar panels are built, which are more suitable for use in the higher latitudes.
However near, or far, from the equator, if the aspect of the property is good (south to southwest facing) the panels will receive greater solar radiation than those facing in any other direction. Another factor that appears to play a part, is whether the property is on the east or west of a country. It seems that the western parts of many countries receive more solar radiation.
You might expect a property with a south to south east aspect to be on a par with one on a south to south west aspect, but this is not the case. Early morning sun often appears lower in the sky. There is often mist or cloud about just after dawn, which affects the amount of solar radiation reaching the panels.
Any shading effect, however weak, will affect the efficiency of all the panels, as the unit will work at the capacity of the weakest (shaded) one. Apart from this general cause affecting the efficiency of the panels, local conditions can also affect their efficiency.
This might occur because one house is in a slight dip and gets shaded by the top of their neighbor’s house, or tree, or even the slight rise to the side. The neighbors either side could miss this entirely as their properties are built on slightly higher ground.
Conversely, a house in what is normally a cool area with few hours of sunlight, may be situated so that it gets every minute of sunlight in that area. This house will collect the optimum amount of solar radiation and get more solar energy than those nearby.
Do your math carefully before you purchase solar panels. Output counts as much as cost. You have to purchase the smartest system for your home if you want to save money by going solar.