What affects the performance of the solar system?
Good data is available which enable us to predict how much solar irradiation will be available throughout the year across the entire planet and thus, predicting the likely annual output of your solar power system. However, a number of variables can affect the performance levels of your solar system.
The first is the geographic location of the solar system. Depending on your latitude, a different amount of energy will be available because your location effect’s how perpendicular the sun is and also, how much atmosphere the sunlight needs to travel through to reach you. The Southern Hemisphere and New Zealand specifically happens to have solid performing latitudes in the world for solar energy.
A secondary effect is local geography, which can affect how much cloud cover or smog is typical. Although solar panels still produce electricity in cloudy or smoggy conditions, the clearer the sky the better the energy production will be. As a rule of thumb, on a cloudy day a solar system will produce around 20% to 35% of the energy it would produce under ideal conditions.
The second major impact on solar generation is the time of year or season. During the changing seasons the earth rotates on its axis changing the perpendicularity of the sun and thus the intensity of the energy reaching us. Logically, it is strongest in summer and weakest in winter and this will affect the performance of solar systems.
By using good data and taking into account location, seasons and geography we can estimate the average annual energy that will be produced, although the day to day levels may vary slightly. From year to year there is some variation but generally sunlight intensity and therefore annual energy production is relatively predictable. Normally orientation of panels, overshadowing or efficiency of solar panels and inverter all contribute to the final renewable electricity generated.