When the total capacity of the panels is greater than the inverter, the solar system is said to be “oversized” and the inverter “overlocked”.
Why is it possible?
The first thing to remember is that quality inverters (read more about best solar inverters in the market here) can handle oversizing up to one third larger than their capacity.
Secondly, panels ratings are indicated as a peak and panels don’t generate at their maximum capacity all day long. Panels are tested under the Standard Test Conditions. These conditions are designed to make it possible to conduct comparisons. It specifies a cell temperature of 25 degrees Celsius, a solar radiance of 1000 per square meter and a 1.5 air mass. Because of the weather, the temperature, the panels orientation or their angle toward the sun, conditions are rarely like the STC.
Panels reach their maximum capacity during the peak available sunshine for only 1-2 hours during the day. The rest of the time, the output is lower. When the maximum DC output from the panels exceed the maximum output of the inverter, the inverter will clip the output to make itself less efficient and match the maximum capacity (see graph below).
Why oversizing?
By oversizing the array, the system will produce more power in the morning and evening, and during other times of low solar irradiation. When conditions aren’t at their optimum, the system will generate more power than an “undersized” system. While it is unfortunate to waste some power when the inverter clips, the amount of energy lost when clipping is lower than the extra energy solar arrays generate the rest of the day.
Oversizing a system will also increase the amount of time when inverters are operating at their nameplate.
Source https://www.electronicsmedia.info/ capacity.
How much can I oversize my array by?
The Clean Energy Council Solar PV Design Guidelines allow you to oversize your array by up to 33% (DC to AC capacity). Over this limit, government incentives cannot apply.
Things to consider when oversizing:
When oversizing, only use good quality inverters and have your system installed by professional CEC accredited. Whilst it is important to have a good system design when it comes to solar in general, it is essential when oversizing.
What about undersizing?
It is also possible to undersize a solar system. This allows you to upgrade by adding panels in the future.
If you are considering a solar power system and need some advice on solar inverters, call Energis on 1300 782 217 or at sales@energis.com.au One of our solar consultants will talk you through the best option for you.
