When installing a solar system, you need an appropriately sized inverter that matches the output of your solar array. Solar inverters are the unsung heroes of your solar system, transforming direct current (DC) power generated by your solar panels into alternating current (AC) electricity.
A properly sized inverter helps your system operate at its best, maximising energy production and savings. The two primary factors affecting solar inverter size are panel productivity and geographical location. A reliable solar provider like Plico will talk you through inverter options and help you find the best match for your system.
What is a solar inverter?
A solar inverter converts energy from solar panels into usable electricity for your home. Your home appliances run on AC electricity, but solar panels produce DC electricity, so you need an inverter in between to make it all work. There are many different types of solar inverters, from string inverters to hybrid inverters.
When inverters were first invented in the 19th century, they were mechanical, consisting of a spinning motor to change the DC source connection from forward to backward continuously. Luckily, it’s all electrical now, with no moving parts. Without a proper solar inverter, your solar panels' hard work to create solar energy goes to waste.
It may sound complicated, but Plico makes greater energy independence easy and accessible. Simply chat with a team member to get information specific to you, or read our article on solar inverters and battery storage for more information about solar inverters.
Why does the size of my solar inverter matter?
The inverter is the heart of your solar setup, so getting it sized correctly increases its cost-effectiveness and ensures you benefit from efficient energy all year round.
The size of your solar inverter matters because it determines how efficiently and safely your solar energy system converts solar power into usable electricity and manages your energy flow. Here are the key reasons why inverter size is critical:
Optimal Efficiency: If the inverter is too small, it will "clip" excess power when the panels generate more than the inverter's capacity, wasting energy. If the inverter is too large, it may operate inefficiently during periods of low solar production (e.g. early morning or cloudy days).
System Compatibility: The inverter size must match the total capacity of your solar panels. Undersized inverters may not handle peak production, leading to energy losses. Oversized inverters can be unnecessarily expensive and may not meet optimal operating conditions.
Energy Management: A properly sized inverter ensures your system generates enough power to meet your household needs. It should accommodate both your current energy consumption and any expected increases (e.g. adding appliances or electric vehicles).
Grid Compliance: Many utilities have limits on the maximum inverter size to prevent overloading the grid, so an oversized inverter might not meet regulations.
Supports Battery Storage: If you have, or plan to add, batteries, the inverter must be compatible with energy storage and have the capacity to manage both solar and battery inputs.
Longevity & Cost: Prevents wear from overuse or overspending on an oversized inverter.
In some cases, a system may handle an oversized inverter if you plan to expand your system later. However, inverters work best when close to their capacity, so using solar power with an oversized inverter for too long may impact your energy efficiency down the line.
How to calculate the size of a solar inverter
The size of your solar inverter is typically calculated from the size of your solar array. The inverter should closely match your panel capacity (80-100% of the array size). For example, if you install a 6 kW solar PV system, you’ll need a minimum 5 kVA inverter.
When you install your solar system, your solar provider should discuss inverter options with you, as well as assess your system to determine which size inverter you need. They will consider not only the capacity of your solar array, but any future considerations and regulations.
They may also consider factors such as geographical location or solar panel orientation affecting energy production. Solar panels that are predominantly shaded, or households in areas with little to no sunlight, tend to produce less electricity on average. You may be able to opt for a smaller inverter if your solar panels consistently underperform due to environmental elements.
Solar inverters are measured in kVA (kilo-volt-amperes), which is a measure of apparent power, while kW is a measure of actual power. In a 100% efficient system, kW and kVA are the same.
Different solar inverter sizes
Solar inverters are available in various sizes. Residential solar inverter sizes typically range from 1 kW to 10 kW, depending on the home's energy needs. Small systems, between 1 kW and 3 kW, are suitable for homes with low energy consumption or limited roof space. Medium-sized systems, commonly between 3 kW and 5 kW, cater to average households with moderate energy needs. A 5 kW inverter is the most popular choice for residential installations, as it balances energy requirements and cost, accommodating around 12–15 panels or more if paired with a solar battery.
Larger residential systems, ranging from 6 kW to 10 kW, are ideal for homes with high energy demands, such as those with air conditioning, pool pumps, or electric vehicles. For homes integrating battery storage, hybrid inverters are available in similar sizes (5–10 kW) to manage both solar generation and battery charging. A 5 kW hybrid inverter meets the needs of most battery-integrated systems, while a 10 kW hybrid inverter is ideal for larger setups. Choosing the right inverter size depends on current energy use, future needs, and the capacity of the solar array, ensuring optimal performance and efficiency.
Typically, inverter sizes for single-phase houses are limited to 5 kW, and for three-phase houses, they can go up to 15 kW. Keep in mind that your electrical network service provider may impose solar export limitations, and this may affect your inverter size. Solar export limits are restrictions placed on solar systems, reducing the amount of energy exported to the grid. You may purchase a large inverter, but if its export is limited, you won’t make as much from feed-in tariffs (payments for the energy you export to the grid from your solar system) as you originally thought. If your inverter produces more than 5 kVA (kilovolt amperes), it will have an export limit of 1.5 kW. Some inverters have a special function that automatically reduces energy so it doesn’t exceed the export limit.
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How does inverter size affect my system’s performance?
The size of your inverter will impact how much solar energy can be converted to usable electricity at any given time. If you go with a 5 kVA/ 5 kW inverter, the maximum amount of solar energy that can be provided to your home is 5 kW. This is the case even if your solar panels are producing more than 5 kW. At the same time, the maximum amount of solar energy you can feed to the grid is also 5 kW, not considering any solar energy that may be used in your home. If your energy use regularly exceeds 5 kW for long periods of time, you may want to consider a larger inverter.
If you have a hybrid inverter that controls both solar panels and a solar battery, then the maximum amount of energy you can draw from the battery at any time is also 5 kW if you have a 5 kW/ 5 kVA inverter.
If you have a separate solar and battery inverter, your solar inverter will convert energy from your solar panels at the rate of the capacity of your solar inverter and will charge and discharge your battery at the rate of the capacity of your battery inverter.
Will my solar battery impact the size of my inverter?
Your choice of solar battery will influence your inverter size. Solar batteries play a significant role in storing the excess energy your solar panels generate for later use. When you decide to integrate a battery into your system, it affects the overall power flow and efficiency.
The type of inverter you have and how the battery is integrated into the clean energy system can impact the size of your inverter.
Hybrid Inverters: A hybrid inverter combines the functions of a solar inverter and a battery inverter, managing both solar generation and energy storage. If you have a larger battery, you might need a larger inverter to handle both the solar panel output and the charge/discharge rates of the battery simultaneously. For example, if your battery is capable of discharging at a high rate, you’ll need an inverter that can match that output to avoid limitations.
Separate Inverters for Solar and Battery: If your system uses separate inverters for solar and battery storage, the solar inverter size will still be primarily determined by your solar panel capacity, while the battery inverter will be sized based on the battery's charge/discharge capacity. In this case, the battery inverter doesn't directly affect the size of the solar inverter, but it’s still important to ensure both inverters are sized appropriately for optimal performance.
System Compatibility: Both the inverter and battery need to be properly sized and compatible with each other. If the inverter is too small, it may not be able to fully charge or discharge the battery, reducing the overall efficiency of the system.
In summary, while your solar battery doesn’t directly determine the size of your inverter, it does play a key role in ensuring that the inverter can manage both solar generation and battery storage efficiently.
The exact impact of your solar battery on inverter size depends on factors like battery capacity, inverter compatibility, and your specific energy usage patterns. It’s best to speak with your solar provider to discuss the right inverter size, accounting for the battery.
How do I know which solar inverter size is right for me?
The best way to find the right-sized solar inverter is to consult with a trusted solar provider like Plico. We’ve been in the solar game since 2019, so we know a thing or two about inverters. We’ll guide you through the process, from choosing your system to installation and performance monitoring.
Our experienced team can conduct a no-obligation site visit to assess your home and recommend a solar system that fits your household’s energy needs. When it comes to inverters, we’ll ensure all components of your system are compatible and running at peak efficiency, helping you save money and enjoy greater energy independence
Ready to start your solar journey? Chat with the switched-on people at Plico on 1300 175 426 or check out our range of products.
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