If you’ve looked into the Sigenergy SigenStor solar battery system, you’ve likely seen plenty of inverter size options but not much guidance on which one is right for you.
That’s a completely reasonable thing to be confused about. Most people don’t spend their days thinking about inverters. And when you’re about to spend a significant amount of money on a solar and battery system, “just trust us” isn’t good enough. You deserve a real answer.
At PSC Energy, we’re here to help. We focus on inverters every day so you don’t have to. Today, our goal is to guide and inform you.
In this article, you’ll learn about the following:
- What Does an Inverter Do?
- Why Do Solar Panels and Inverters Have Different Sizes?
- How the SigenStor Changes the Oversizing Rules
- Single-Phase vs. Three-Phase: Why It Matters for Your Inverter
- What Inverter Sizes Are Available for the SigenStor?
- How Much Battery Storage Do You Need?
- What Happens If You Get the Inverter Sizing Wrong?
- Can You Expand SigenStor Later?
- The Key Factors That Go into Choosing Your Inverter Size
- FAQ: Sigenergy SigenStor Inverter Capacity
By the end of this article, you’ll know what an inverter does, why its size is important, and how to choose the right size for your home.
Let’s get started.
What Does an Inverter Do?
Before we talk about size, it helps to understand the job.
- Your solar panels generate electricity as direct current (DC).
- Your home runs on alternating current, or AC power.
These two types of electricity don’t work together. It’s similar to trying to fit a US plug into an Australian socket—they both carry power, but they aren’t directly compatible.
The inverter is what bridges that gap. It takes DC electricity from your panels and converts it to AC electricity that your home can use. Everything your solar system sends to your lights, your fridge, and your TV goes through the inverter first.
The inverter’s capacity, measured in kilowatts (kW), sets the maximum amount of power it can convert and send to your home at once.
A 10kW inverter can handle up to 10 kilowatts of power flow at once.
This is why inverter size is important. If it’s too small, you waste potential energy. If it’s too large, you pay for capacity you don’t use. Choosing the right size helps you get the most from your investment and your system’s performance. It’s a key decision.
If you’d like to learn a bit more about SigenStor, a solar battery we carry, we recommend you check out the following article titled, Sigenergy SigenStor Review.
Why Do Solar Panels and Inverters Have Different Sizes?
Many homeowners are surprised to learn that oversizing means your solar panels can produce more power than your inverter can handle at once. It’s actually normal—and even preferred—for your panels to be larger than your inverter.
This is called oversizing, and it’s standard practice across the solar industry.
Here’s why this approach makes sense:
- Your solar panels only hit their rated capacity under ideal conditions (clear sky, optimal sun angle, perfect temperature).
- Most days involve some cloud cover, some shade, some less-than-perfect angle to the sun.
If you matched your inverter size to your panels’ peak output, your inverter would spend most of its time underused, working below its capacity.
By installing more panel capacity than inverter capacity, your inverter works closer to its full potential on most days. This way, you collect more energy, even when conditions aren’t ideal.
It’s similar to buying jeans with a bit of extra room for comfort, rather than a tight fit that only works in one situation.
For standard solar systems without a battery, the industry norm is a DC-to-AC ratio of around 1.33. That means for every 10kW of inverter, you’d install up to 13.3kW of solar panels.
DC systems are permitted to be oversized by up to 200%, which aligns well with what the SigenStor supports for single-phase homes. For three-phase homes, the oversizing limit is 1.6:1. So a 10 kW inverter can support up to 16 kW of solar.
However, it’s important to know that NSW network distributors have their own approval rules. What’s allowed for your property may vary, and the 200% limit doesn’t guarantee every setup up to that point will be approved.
With a hybrid system like the SigenStor, those rules change, and they change in your favour.
If you’re interested in learning a bit more about oversizing, you might want to check out the following article titled, Oversizing Your Solar Panel System: How to Maximise Your Panels for Bigger Returns.
How the SigenStor Changes the Oversizing Rules
The SigenStor is a hybrid inverter system, meaning it integrates your solar panels and battery storage. This is why it can support much higher panel-to-inverter ratios than a standard system.
The main difference is in how energy flows through the system.
In a traditional solar setup, all the energy must go through the inverter—either to be converted from DC to AC for your home, or from DC to AC and then back to DC to charge a battery. This double conversion is inefficient and can slow things down.
The SigenStor avoids this bottleneck in two key ways:
- Your inverter isn’t the only pathway for energy. Excess solar energy can flow directly from your panels into the battery in DC form, bypassing the inverter.
- Surplus energy isn’t wasted. On sunny days, when your panels make more power than your inverter can handle, the extra energy goes straight into your batteries instead of being lost.
If you have a 10kW inverter and 20kW of solar panels:
- Your 10kW inverter handles up to 10kW for your home.
- Your 20kW of panels are producing, say, 18kW on a good day.
- The remaining 8kW that the inverter can’t process flows directly to the battery.
In a standard system, that surplus would simply be clipped.
With the SigenStor, while your inverter manages 10 kW for your home, up to 10 kW can also go straight into your batteries at the same time. This happens when your solar panels are producing 20 kW of power.
Over a full hour of good sun, that’s 10 kWh of stored energy waiting to power your home tonight, captured efficiently, without a single conversion loss.
Direct-to-battery charging is a major benefit of SigenStor. It helps your system capture more of the energy your panels make, giving you better performance and more value.
If you’d like to learn a bit more about the cost of SigenStor, we recommend you check out the following article titled, How Much Does the Sigenergy SigenStor Cost?
Single-Phase vs. Three-Phase: Why It Matters for Your Inverter
One of the first things we need to establish before recommending an inverter size is whether your home is on single-phase or three-phase power. If you’re not sure which you have, you’re not alone. Most people have never needed to think about it before installing solar.
Single-phase power is a two-wire circuit: one active wire that carries current into your home, and one neutral wire that completes the circuit back. About half the homes in NSW are single-phase.
Three-phase power uses three active wires instead of one, with a neutral wire completing the circuit. Because the three active wires have different frequencies, their peaks and troughs don’t align, resulting in a much smoother, more consistent flow of power. Three-phase connections are common in larger homes with heavy energy demands and are standard in commercial buildings.
How do you know which you have? The simplest method is to look at your switchboard. If you see three rows of circuit breakers (or a main switch that’s clearly wider than a standard switch), you’re likely three-phase.
This is important for your SigenStor because single-phase and three-phase connections allow different levels of oversizing. This is a key factor when choosing your system setup.
For single-phase homes, the SigenStor allows up to 200% oversizing. That means a 10kW single-phase inverter can support up to 20kW of solar panels. That’s a very generous ratio, and it’s made possible by the direct-to-battery charging we described above.
For three-phase homes, the ratio is 1.6, so a 10kW three-phase inverter can support up to 16kW of solar panels. The ratio is lower because three-phase systems are already distributing power across three circuits rather than one, which changes how the grid and the inverter interact.
The key takeaway: neither ratio is better or worse; each is calibrated for what its connection can safely and efficiently handle.
If you’re interested in learning a bit more about single-phase and three-phase sites, you might want to check out the following article titled, Single-Phase vs. Three-Phase: How Are They Different?
What Inverter Sizes Are Available for the SigenStor?
The SigenStor comes in a range of inverter sizes to suit different homes and energy needs.
For single-phase homes, the available options are 6kW and 10kW.
For three-phase homes, the options are 5kW, 10kW, 15kW, 20kW, 25kW, and 30kW.
The three-phase range is wider because these homes often have more varied energy needs, from large family homes with lots of air conditioning to small commercial buildings.
The single-phase range is more focused because most single-phase homes fall into a fairly predictable energy-demand profile.
If you’d like to learn a bit more about the cost of SigenStor, we recommend you check out the following article titled, How Much Does the Sigenergy SigenStor Cost?
How Much Battery Storage Do You Need?
Choosing an inverter and battery go hand in hand—you need to consider both together. Here’s how to think about typical setups.
16kWh of battery storage is a solid starting point for a typical household. At this capacity, a 5kW inverter paired with around 8kW of solar panels is usually a good match. The solar array is sized to reliably fill the battery on most days, including overcast days where output is reduced.
Many households choose 24kWh of battery storage once they factor in bigger loads like ducted air conditioning, electric hot water, EV charging, or a larger home.
At this level, you’ll need at least a 10kW inverter with about 9kW or more of solar panels. The bigger inverter helps make sure your battery charges fully, even on shorter winter days when solar output drops.
If your inverter is too small relative to your battery, you’ll regularly find your battery only partially charged by evening, which means you’re drawing from the grid exactly when you were hoping not to.
These are just general guidelines. Every home is unique, and the best setup depends on when you use electricity, what appliances you have, whether you own an EV, and your goals—like lowering bills, being more self-sufficient, or preparing for outages.
If you’d like to learn about some of the potential downsides to the SigenStor energy system, you might want to check out the following article titled, Problems with Sigenergy SigenStor Solar Energy System.
What Happens If You Get the Inverter Sizing Wrong?
It’s important to be honest—choosing an inverter that’s too small is a common mistake.
If your inverter is too small for your panel array, you’ll lose energy to clipping when your panels generate more than your inverter can handle, and that surplus just disappears.
In a standard system, this energy is always lost. With the SigenStor, direct-to-battery charging helps reduce this loss, but you’ll still face limits if your panels are much larger than your inverter.
If your inverter is too small for your battery, your battery will regularly finish the day partially charged. This defeats a significant part of the purpose of having a battery, and you’ll find yourself drawing from the grid during evening peak hours, which is exactly the expensive and grid-dependent behaviour you installed a battery to avoid.
If your inverter is too big for your panels or battery, you’re just paying for extra capacity you won’t use. The inverter will still work, but you’ll have spent more than necessary.
Getting the size right really matters. It’s not something to guess or estimate roughly.
If you’d like to learn a bit more about Sigenergy’s SigenStor, you might want to check out the following article titled, Pros and Cons of the Sigenergy SigenStor Solar Battery and Energy System.
Can You Expand SigenStor Later?
A real advantage of the SigenStor is its modular design. You can add battery modules over time, so if your energy needs grow—like getting an EV, adding ducted air conditioning, or having a bigger household—you’re not stuck with your original setup.
Here’s a realistic example of how this can play out. Say you start with a 10kW inverter and 16kWh of battery storage. Life changes, and you buy an electric vehicle, and suddenly, your nightly energy draw is significantly higher.
With the SigenStor, you can add battery modules to bring your storage up to 24kWh or beyond, absorbing that increased demand without replacing the rest of the system.
Changing the inverter later is more difficult. Replacing it isn’t impossible, but it means extra work, possible new approval from your grid provider, and extra costs. Adding more solar panels later is easier than you might think, but it still requires a site visit, more installation, and possibly changes to your grid approval.
The main takeaway is that expanding your battery is easy with SigenStor. Changing the inverter or adding panels is possible, but it takes more effort.
While SigenStor lets you expand your storage over time, it’s still smart to think carefully about your inverter size from the beginning—especially if you expect your energy needs to grow in the next few years.
If you’re interested in learning a bit more about solar panels and energy systems, you might want to check out the following article titled, Are Solar Panels Worth It in NSW, Australia? A Price Breakdown for 2025.
The Key Factors That Go into Choosing Your Inverter Size
To sum up, here are the main things to consider when choosing your inverter:
Your home’s energy demand. How much electricity do you use, and when do you use it? A household that uses most of its power in the evening has different needs from one that runs high loads during the day.
Your phase connection. Single-phase or three-phase determines which inverter options are available and what oversizing ratios apply.
Your battery storage goals. How much storage do you want, and how quickly do you want to charge it? A larger battery needs a proportionally capable inverter to charge reliably.
Your available roof space. More roof space means more panels, which may push you toward a larger inverter to manage that capacity effectively.
Your future plans. If you’re planning to get an EV, build an extension, or add a pool, your energy needs will go up. It’s smart to size your system for where you’ll be in three to five years, not just today.
Your grid provider’s limits. What’s the maximum inverter size your distributor will approve for your property?
None of these factors stand alone. The right inverter size balances all of them for your situation. That’s why talking with an experienced installer is the best way to find a solution you’ll be happy with for years.
If you’re interested in solar batteries, you might want to check out the following article titled, Are Solar Batteries Worth It in NSW? PSC’s Ultimate Guide for 2026.
Final Thoughts: Phase the Facts
One of SigenStor’s real strengths is its range of inverter options. There’s a setup for a small single-phase home aiming for energy independence, and another for a large three-phase home with high power needs.
Knowing how oversizing works, how direct-to-battery charging helps, and what your home really needs is the foundation for making a confident decision. Hopefully, this article has helped you build that foundation.
If you have any questions we haven’t covered, we’re always happy to discuss them with you. It’s what we do.
If you’re interested in learning a bit more about solar and battery rebates in NSW, Australia, you might want to check out the following article titled, Ultimate Guide to Australia’s 2026 Solar Rebate and Battery Rebate: Federal and NSW Rebate for Solar.
FAQ: Sigenergy SigenStor Inverter Capacity
What does an inverter do in a solar system?
An inverter converts the direct current (DC) electricity generated by your solar panels into alternating current (AC) electricity that your home can use. Every appliance in your home runs on AC power, so without an inverter, the electricity your panels produce would be unusable. The inverter’s capacity, measured in kilowatts (kW), determines the maximum amount of power it can convert and deliver to your home at any given moment.
What inverter sizes are available for the Sigenergy SigenStor?
The SigenStor comes in a range of sizes depending on whether your home is on a single-phase or three-phase power connection. For single-phase homes, the available options are 6kW and 10kW. For three-phase homes, the options are 5kW, 10kW, 15kW, 20kW, 25kW, and 30kW.
Why are solar panels often larger than the inverter they’re connected to?
This is called oversizing, and it’s standard practice across the solar industry. Solar panels only hit their rated capacity under ideal conditions; clear skies, optimal sun angle, and perfect temperature. By installing more panel capacity than inverter capacity, your inverter works closer to its full potential on average real-world days, including overcast ones. You harvest more energy more consistently without paying for an inverter that’s almost always underworked.
What is the DC oversizing ratio for the Sigenergy SigenStor?
The SigenStor supports up to 200% DC oversizing on both single-phase and three-phase systems. This means a 10kW inverter can support up to 20kW of solar panels. This is significantly more generous than the standard industry ratio of 1.33 for systems without battery storage and is made possible by the SigenStor’s ability to charge its batteries directly from DC power, bypassing the inverter entirely.
How does the SigenStor support higher oversizing ratios than a standard solar system?
In a standard solar system, all energy must pass through the inverter, creating a bottleneck. The SigenStor removes this bottleneck by allowing excess solar energy to flow directly from the panels into the battery while still in DC form, completely bypassing the inverter. This means the inverter isn’t the only pathway for energy to travel. On a sunny day when your panels are generating more than your inverter can handle, that surplus flows straight into your batteries rather than being clipped and lost.
What is the DC oversizing rule for solar systems in NSW?
In NSW, DC solar systems are permitted to be oversized by up to 200%. The SigenStor’s 200% oversizing support aligns with this allowance. However, NSW network distributors, including Ausgrid, Endeavour Energy, and Essential Energy, have their own approval requirements that apply to your specific property and connection. The 200% ceiling is not a guarantee that every configuration up to that limit will be automatically approved. Always confirm with your installer what your local distributor will approve before finalising your system design.
What is the difference between single-phase and three-phase power, and how do I know which one I have?
Single-phase power is the standard residential connection, using one active wire and one neutral wire. Three-phase power uses three active wires, delivering a smoother and more consistent power supply. It’s common in larger homes with heavy energy loads and in commercial buildings. To find out which you have, check your switchboard. If you see three rows of circuit breakers, or a main switch that’s noticeably wider than a standard switch, you’re likely on three-phase. If you’re still unsure, your electricity retailer or a licensed electrician can confirm it quickly.
What happens if my inverter is the wrong size?
Getting the sizing wrong has real consequences in both directions. If your inverter is too small for your panel array, you’ll lose energy to clipping on good solar days, though the SigenStor’s direct-to-battery charging mitigates this to a degree. If your inverter is too small for your battery, your battery will regularly finish the day partially charged, leaving you grid-dependent during evening peak hours. If your inverter is too large for your system, you’ve simply overpaid for capacity you’ll never use. Getting the balance right from the start is worth the effort.
Can I expand my SigenStor system in the future?
Yes. The SigenStor’s modular design means you can add battery modules over time as your energy needs grow. If you buy an electric vehicle, add ducted air conditioning, or simply find your household’s energy use increasing, additional battery capacity can be integrated into your existing system without replacing it. What’s harder to change later is the inverter itself. Swapping it out involves additional labour, potential re-approval from your network distributor, and extra cost. Battery expansion is easy; inverter changes are possible but involve more friction. It’s worth sizing your inverter with your future needs in mind from day one.
What should I consider when choosing an inverter size?
The right inverter size depends on several factors working together: your home’s overall energy demand and when you use it; whether you’re on single-phase or three-phase power; how much battery storage you want and how quickly you need it to charge; how much roof space you have available for panels; any plans that might increase your energy needs in the next few years, such as an EV or home extension; and what your local network distributor will approve for your property. No single factor determines the answer on its own, the right size is the one that balances all of them for your specific situation.
