One of the key components in a solar power system is the solar inverter. It converts solar energy from the solar panels (DC electricity) into AC electricity that you can use in your home.
Many manufacturers in the solar market claim to sell the best solar inverter. So how do you choose one?
These are the top 3 solar inverters on the Australian solar market today.
Our experience and feedback from users of solar systems in Australia confirm that these 3 brands are the best solar inverters on the market.
Why is Choosing the Best Solar Inverter Important?
There are a couple of good reasons why you should spend some time deciding which solar inverter is best for your home solar system:
- A solar inverter is the most complex component in a home solar energy system. Because it’s in constant use, it’s also the component most likely to fail in the system.
- 83% of problems with solar inverters occur in the first 5 years after installation. Most good brands provide a warranty which covers this period. Ideally, the warranty should be for 10+ years.
- The efficiency of the solar inverter affects the overall efficiency of your solar energy system. Certain conditions, such as cloudy weather or an under-sized system can result in less than optimal conversion efficiency.
You should choose a solar inverter based on the size and location of your home solar system. And your predicted solar energy consumption.
What Do Solar Inverters Do?
The solar inverter collects all the solar energy from the solar panels. It then converts this into electricity you can use in your home.
Solar inverters also include an anti-islanding mechanism. This senses when there is a problem with the main power grid and automatically stops the feed of electricity to the grid.
TIP: Any solar inverter you buy should be approved for use in Australia by the Clean Energy Council (CEC). It should also comply with the AS 4777 standard for the country.
Don’t entertain buying a non-approved solar inverter! If it’s not on the approved list for use in Australia, you won’t get the solar rebate or similar state-level solar incentives. Your home solar system components must be approved by the CEC. And your solar installation company should also be approved for you to qualify for federal and state solar incentives.
Types of Solar Inverters
- The most common option- suitable for most homes.
- It’s also the simplest and cheapest type of inverter.
- A series of solar panels (solar array) feed into the inverter.
- Typically, the inverter is wall-mounted, near the existing electrical switchboard in the home. This type of solar inverter works well in most cases.
Expect to pay from $1000 to more than $2000 for a high-quality string inverter.
- Good for solar systems which suffer from partial shade.
- Each solar panel has its own microinverter.
- Solar panels and micro inverters can be either separate components or ‘integrated’ (AC solar Module).
- A solar energy system including microinverters is more expensive than a system with a string inverter.
- Microinverters are located on the roof with the solar panels, so they are more exposed.
- Individually, microinverters might be less efficient than a high-quality string inverter. But overall system efficiency is typically 12% better as each panel is optimised individually.
- If a solar panel fails, only the output from one panel is lost.
A microinverter costs about $200. But you need one for each solar panel. A typical home solar energy system with microinverters will cost about 20% more than an equivalent system with a string inverter.
- A single unit that connects solar panels to solar battery storage.
- Basically, a string inverter that can accommodate battery storage.
- It enables the system to run during power outages or blackouts.
- A hybrid inverter is more expensive than a string inverter. (But they’re becoming cheaper!)
You can find decent ones for $1000-$2000. But some of the top-notch brands cost more than $3000.
- This connects your existing solar energy system to a battery.
- It’s easier to add a battery inverter to an existing system than swap out the old inverter for a hybrid model.
- A battery inverter can charge your solar battery. It can also convert the stored battery energy into AC electricity to use in your home.
Including a dedicated battery inverter to deal with a solar battery bank for energy storage will increase installation costs by about $2000-$3000.
- Strictly, it’s not an inverter. You install them with a string inverter and solar panel strings.
- A power optimiser in an alternative solution for solar panels that suffer from shade.
- It works the same as a microinverter. If solar panels fail or become shaded, the optimiser stops the panel’s low output affecting the rest of the system.
- Power optimisers can be expensive, although less than opting for microinverters.
These are slightly cheaper than microinverters, less than a few hundred dollars. Typically, you’ll only fit them to panels which suffer from shade – not all panels, so it’s cheaper overall than a system with microinverters.
Which Solar Inverter Brand is Best for a Solar Power System?
There are various popular brands on the Australian solar market, as mentioned earlier. These are the top 3 according to the consumer watchdog CHOICE. All 3 brands offer high-quality construction and full after-sales service.
Suitable for 6.0/6.6kW single-phase home solar systems
TIP: One of the best ways to choose the best solar inverter is to read reviews online from solar users in your local area. Geographic location can affect system efficiency. If the majority of solar system users in your area favour a particular brand of solar inverter, there’s a good reason for that. Don’t ignore it! Real-life case studies can be a mine of useful information before you decide to buy.
How Much Should I Pay for a Solar Inverter?
In many cases, it can be difficult to isolate the cost of just the solar inverter. This is because a quote for a grid-connected home solar system is usually all-inclusive. Although, generally speaking, the inverter accounts for about 20% of the overall cost of system installation.
At the bottom end of the solar inverter range, you can buy a budget 3kW inverter for about $800 (brands like Sungrow and ZeverSolar). And prices for top of the range 5kW inverters like those from SMA and Fronius cost about $1500 to $1700.
The 5kW solar inverter is the most common model because it can handle up to 6.6kW capacity of solar panels. This is currently considered optimal for a home solar system.
TIP: Avoid budget inverters at all costs. They won’t last in the intense Australian sun. You’ll end up replacing it sooner than you’d like. And it’s a false economy in the long run. Always choose the best quality you can afford for hassle-free operation over many years.
What Size of Solar Inverter Should I Buy?
As we mentioned before, a solar inverter with a capacity of 5kW is the most common type installed in residential solar systems across Australia.
The solar inverter you buy needs to handle the maximum output of your solar system, as a minimum requirement. So, a 5kW home solar system will need a 5kW solar inverter. But it’s not that simple!
Any system where there is some form of energy conversion will be subject to system losses. Theses losses typically occur in the panels, cabling, and inverter. No system operates at 100% efficiency all the time.
This means that the solar inverter you install could be rated at 25% less than the maximum solar energy output from your panel array. There are specific CEC guidelines for undersizing and oversizing a home solar system.
TIP: Remember the rating of solar inverters specifies their maximum input in DC and output in AC. You need to match the input rating of the solar inverter to the output rating of your solar panel array (DC-DC).
Is it Worth Buying a Bigger Inverter?
This seems like a logical choice. Maybe you’ll want to add some extra solar panels in the future. So why not future-proof the system by investing in a bigger inverter from the get-go.
Before you go down that road, consider these points:
- Do you have extra space for more panels?
- When would you plan to install extra panels?
- If it’s such a good idea, why not install extra panels now?
If you have no extra space to expand your solar array in the future, there’s little point in investing in a bigger inverter.
Also, think about the rate at which solar technology is developing. There’s a chance that in the future your existing panels won’t be available anymore.
Expanding capacity with alternative solar panels might result in incompatibility issues. You might end up needing to install another separate string of panels. So any benefit of simply buying a bigger inverter will be completely negated.
One solution to this potential problem is to install an inverter which can handle multiple strings of solar panels. But this is more expensive!
The best approach to planning your home solar system is to install as many solar panels as your roof (or other space) will allow. And choose an inverter that can handle the maximum output of the panels. This is a lot easier than trying to plan how to expand your system in a few years.
How Big is a Solar Inverter?
Popular solar inverters in the Australian solar market are of different shapes, sizes, and weights. But here’s a guide based on the 3 most popular brands in Australia:
- Enphase microinverter: weight 1.08kg, 212 × 172 × 30mm
- Fronius Galvo/Primo: weight 16.4 -16.8kg, dimensions 645 × 431 × 204 mm
- SMA Sunny boy: weight 16kg, dimensions 470 × 435 × 90 mm
A regular string inverter is best installed close to your electricity meter and electrical switchboard. It should also be in the shade and not in direct sunlight.
Microinverters are different because they are typically fitted on the rear of each solar panel.
Is a Solar Inverter Weather-Proof?
Some are. For example, the Fronius Galvo and Primo models have an IP65 rating for their housings. This means they’re water and dust-resistant, so can be installed outdoors.
The Enphase IQ7 and IQ7+ microinverters are approved for installation in wet conditions and come with Class II double-insulated, corrosion-resistant polymeric enclosures.
Not all on-grid solar inverters are weather-proof. It’s possible to buy an additional weather-proof housing if the inverter needs to be located outside. But that will be an additional expense for you.
Make sure to check this detail with your solar installer, and where they plan to locate the string inverter in your home solar system.
What is a Good Warranty for a Solar Inverter?
The lifespan of a regular solar inverter should be between 10 and 20 years. But as we mentioned earlier, the inverter is often the component in a home solar system that fails first. So a good warranty covering parts and labour will give you peace of mind.
Fronius and SMA both offer a 10-year warranty on their solar inverters. Enphase provides a 25-year warranty on their IQ7 and IQ7+ microinverters.
Many manufacturers now also offer the option of taking out an extended warranty to cover the solar inverter for a longer period. This might come with certain conditions such as a regular service and maintenance plan. So check the small print before deciding to get an extended product warranty. Make sure you know exactly what you get, and what it will cost you.
You should expect at least 10 years of trouble-free operation from a solar inverter.
TIP: Before you make your final buying decision, check the warranty details and technical data sheets for all the components in the proposed system. Check that the manufacturers have a presence in Australia. You don’t want to call a head office somewhere on the other side of the world to get service from your solar inverter manufacturer.
Are Solar Inverters Expandable?
We mentioned earlier that you can run into incompatibility issues when you try to add more solar panels at a later date. It depends on how much time has passed since your home solar system was installed.
If you foresee expanding your home solar system in the future. The best solution would be to design a system using a multiple MPPT solar inverter from the start. You can then add additional strings of solar panels when you want. A solar inverter with multiple MPPT (Maximum Power Point Tracking) capacity can handle multiple solar arrays and even arrays with various orientations. MPPT allows the inverter to optimise the output of each array. Multiple MPPT inverters can optimise each array independently of the other arrays connected to it.
This eliminates any incompatibility issues between trying to add the newest and best solar panels to an older solar panel array. Or having solar arrays with different orientations, which a regular string inverter won’t handle.
Simply create a new array and connect it independently to the Multiple MPPT solar inverter, without affecting the existing solar panels and their operation.
What Data Does an Inverter Display?
Solar inverters typically come with a display which indicates basic information: on/off, standby, etc. Also, some display additional data, for example:
- Daily solar energy generated (kWh)
- The cumulative total of solar electricity generated by the system (kWh)
- Current power generated (kW)
- Total hours of energy production (Hrs)
Top brands of solar inverters provide system monitoring features. This allows you to monitor your system performance via Wi-Fi or Bluetooth connection from your phone, computer or other mobile devices. You can see real-time operational and efficiency data at a glance.
Most people don’t want to wait for their electric bill to arrive to gauge the performance of their home solar system. Remote monitoring and data logging is a must-have feature nowadays. Users expect it and the technology required for manufacturers to enable it is already widely used in everyday life.
If you’re offered a solar inverter without remote monitoring capability – worry! It’s basically an industry norm for any good quality solar inverter.
What is a Good Efficiency Rating for a Solar Inverter?
The efficiency rating of a solar inverter describes how well it converts the solar energy received from the solar panels into AC electricity. This is the electricity you use in your home or can export to the power grid through the FiT (Feed-in-Tariff).
Inverter technology has rapidly improved in recent years. Most current transformerless solar inverters have an efficiency rating of 95% or higher.
For example, the Fronius Primo and Galvo solar inverters have a rating of 96%. And the Enphase IQ7 and IQ7+ microinverters have an efficiency rating of 96.5%.
TIP: Inverter efficiency ratings are normally maximum values. Your solar inverter will not be able to maintain maximum efficiency at all times.
Again, we can’t stress enough that you should always prioritise quality solar equipment over savings on price. A home solar system is a long-term investment. You’ll be happier with many years of problem-free operation rather than saving a few dollars by buying cheap components.