What happens to a solar setup when the sun’s not shining? Watts produced at any instant of time by a solar panel fluctuate constantly, based on cloud cover, temperature, time of year, and other factors. So, the best way to get an idea of what will happen on cloudy days is to use averages and take your geographic location into account.
Average Sunlight Hours
For each region, the amount of sunlight hitting the ground varies, particularly during winter months. For example, in Queenstown, the shortest day boasts approximately 1.7 kWh per square meter of sunlight. This value is crucial when estimating how your panel will perform under cloudy conditions.
A Practical Example
Let’s consider a 100W solar panel installed flat. While it won’t reach its peak efficiency on a cloudy day, it can still generate a respectable amount of energy. Based on the average sunlight hours in Queenstown, a flat-mounted 100W solar panel can expect to produce around 170W for the entire day, even when cloud cover is present.
Use Solar Resources for Precision
For those looking for tailored insights, we recommend utilizing solar resources such as the NIWA Solar View tool. This calculator estimates the solar energy that can be collected by solar at a given address, panel direction and slope within New Zealand. The program combines an image of the local landscape with hourly irradiance data from the nearest climate station with at least 10 years of measurements.
Conclusion
LUX Solar’s calculator give you a rough ballpark of whether you will be able to run what you need over the winter – but if you need more accuracy, NIWA Solar View tool is your best bet!