Inverter is one of the most crucial parts of the solar system, which is installed based on the number of solar panels power output size. Installing a 50 kW inverter, which corresponds to the power of 50 kW solar panels will never achieve such output power in real life. Solar panels rarely produce as much power as their rated capacity, therefore it is possible to add extra panels, which can help the inverter to run at a higher average efficiency.
PV modules have ratings which define how they will operate. Solar panels products have been tested in ideal environments. Their power, current and voltage ratings are all defined at Standard Test Conditions (STC).
STC is defined as operating at:
- 25º Celsius
- air mass equal to 1.5
- 1,000 Watts per square meter solar irradiance
In reality solar panel maximum power is first of all affected by the ever changing weather conditions as well as the location of the solar park (facing south, east-west etc), the geographical location, the angle of inclination, possible shading (other houses, trees, etc). The higher the loss / shading or the so-called non-ideal conditions, the more solar panels need to be added to the system.
Therefore it’s wise to install more solar panels in an array in order to achieve the maximum output of the inverter.
When the total capacity of the solar panels is greater than that of the inverter the panels are usually said to be “oversized” or the inverter “overclocked”. For example when you have a 10 kW output inverter and you install 13 kW of solar panels to it – then your solar park will be 30% oversized.
Solar power park oversizing:
- Oversizing the inverter allows for expansion of the solar array
- Helps to save money
- Increases the productivity of the solar power park and allows to produce more electricity
- The additional power of the panel can helps the inverter to operate at a higher average efficiency
- The inverter spends less time working in low sunlight with lower efficiency
Choosing the right inverter
All inverters on the market can handle up to a third of the total power without problems if the solar system is properly designed. Inverter manufacturers have designed their products so that the voltage and current entering the inverter never exceed their specified limits.
Sometimes the choice of inverter depends on the magnitude of the oversizing of the solar park. Some inverter manufacturers are able to offer more flexible solutions meaning a greater possibility of oversizing. The most popular are inverters from Sungrow and Huawei.
While the maximum input power of a 50 kW Sungrow inverter is about 65 kW then Huawei 50 kW rated power inverter has a maximum input power of about 58 kW. Based on this, it can be seen that almost 7 kW more solar panels can theoretically be connected to one manufacturer’s inverter. On the other hand newer inverter manufacturers allow up to 1.5 x oversizing, such as Growatt inverters. It’s always wise to double check with your installer which inverter is most appropriate for your solar power park.
The recommended percentage of overdimension is between 20% and 35%. It is important to follow local electrical codes and use qualified electricians and installers. Also solar power park documentation will include all of the necessary inverter instruction and safety instruction.
Based on Sunergia experience, all of the solar parks we have built in the Baltics – we have used the opportunity to oversize the inverters, which benefits with more efficient solar power park. We would like to emphasize that everything depends on each individual project, for which the consultation and personal approach is offered by Sunergia’s solar experts.
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