Why You Should Oversize Your Solar Panel Array

The concept of oversizing your solar arrays might sound counterintuitive at first. However, oversizing can actually maximise your energy production and long-term savings. This blog explains what oversizing is, how it works, and if it’s beneficial for your solar panel installation.

What is Solar Panel Array Oversizing?

Oversizing refers to installing a solar array (a group of solar panels) with a higher capacity than your inverter. Typically, solar installers assess your energy consumption patterns and design a system to exactly match your requirements. However, an oversized solar array intentionally produces more energy than your inverter’s AC output power. This allows your PV system to take full advantage of daylight hours and convert more energy for your home.

The Benefits of Oversizing Your PV Array

Maximise Energy During Daylight Hours

Oversizing allows you to generate more kWh each day compared to when the system is not oversized . It allows you to maximise the amount of solar panels on your roof without buying a more expensive inverter. The graph below shows the energy output of an oversized PV system on a summer day with clear skies.

In this example, we have a 6.6 kilowatt array on a 5 kilowatt inverter and an oversized solar array capable of producing 9 kilowatts of power. The inverter cannot convert more than 5 kilowatts of AC power so the power generation is clipped at 5 kilowatts.

Some power does unfortunately go to waste when oversizing. However, in winter there are fewer hours of sunlight and the skies are often cloudy. This will greatly reduce the amount of power the system’s solar array will produce. It’s even possible for the array to produce under the 6.6 kilowatts maximum. This means it wouldn’t make a difference if the system had a 5 kilowatt inverter or a 9 kilowatt inverter on these cloudier days, the system will retain 100% of the energy generated either way.

Higher Inverter Efficiency

Solar inverters work more efficiently near their power limit. By oversizing your solar panel array, your solar inverter will work at its highest efficiency for more hours in the day. This can be seen in the same graph above. The area where the 5 kilowatt inverter is clipping is when it’s operating at its highest efficiency. If you had a 8 kilowatt inverter, the inverter wouldn’t be working at its highest efficiency for as long.

Oversizing with DC Coupled Batteries

Oversizing is great if your system has a DC-coupled battery. Solar inverters convert DC electricity from the solar panels to AC electricity to power your home or business. As mentioned earlier, any solar generation greater than the AC power limit of the inverter is clipped. However, if you have a solar battery connected to the DC side of the inverter, then your inverter can send that excess power straight to your battery. This way the oversized solar array can charge your battery quicker without needing a more powerful inverter.

How Much Can You Oversize Your Solar Array?

In Australia, your solar panel array is allowed to be 133% of the size of the inverter and 200% with batteries. You can have a 5kW Hybrid Inverter with 10kW of panels, and a 7kW battery. You can put 5kW to the battery and 5kW to the house grid. There shouldn’t be any safety hazards with oversizing as long as a reputable company designs and installs your entire solar system.

If you’re considering oversizing the PV array for your solar energy system, contact South West Solar Force. Our team will assess your property and find the best solar panel solution for you.