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In our free technical consultation, on the communication platform on our website,
it often revolves around the differences between 1 and 3-phase inverters and the resulting consequences.

These differences are not insignificant, while 1-phase inverters are almost always compatible with low-voltage storage, 3-phase inverters almost always work only with high-voltage batteries.

1-phase inverters             Low Voltage Storage (48V)                               BMS is already built-in

3-phase inverters             High Voltage Storage                         BMS must be purchased additionally

  

Important: In principle, hybrid and battery inverters should only be operated with storage units for which they are also certified, and for which manufacturers have created a common protocol for each other. Otherwise, malfunctions, limitations, and potentially even security issues may occur, which are not covered by a warranty.

Differences between a 3-phase and a 1-phase inverter

• 3-phase inverters

  are typically used for PV capacities of around 5.5 kWp 

  or higher,

  
  

  as they distribute the higher power across three phases to avoid

  imbalance

  issues.

• A 3-phase inverter distributes its power to three separate phases (L1, L2, and L3), which are present in more than 95% of German households.

  This allows for higher power delivery through even distribution.

  
   

• In practice, however, unsymmetrical loads often occur, where the loads on the phases are not equal or the phase current is not balanced.

  
   

• It is important to consider the extent to which 3-phase inverters can work unsymmetrically.
  Some 3-phase inverters can only deliver 1/3 of their total power on each phase, while some are capable of handling up to the maximum allowed imbalance of 4.6 kVA.

• 1-phase inverters

  generate alternating current on one phase and are typically used for smaller solar installations up to 5 kW (4.6 kVA) output in residential homes.
  Depending on the orientation, they can support PV power of up to 5.4 kWp for south-facing installations, and even 7 kWp for east-west orientation.

• In Germany, a 1-phase inverter is only approved for AC output power up to

  4.6 kVA

  .

• 1-phase hybrid/battery inverters are typically

  only compatible with low-voltage storage systems from specific manufacturers

  .

For example, the very popular Pylontech US Battery Series is only compatible with specific single-phase inverters.

Nur ein einziger Hersteller, die französische Firma Imeon Energy, hat einen dreiphasigen Wechselrichter im Programm, der mit den US2000C, US3000C, und US5000 Akkus kompatibel ist.

Hingegen gibt es einige einphasige Wechselrichter, die mit diesen US Low Volt Speichern von Pylontech kompatibel sind, die Geräte der Firma Sofa Solar, GoodWe und Solis. Only one manufacturer, the French company Imeon Energy, offers a three-phase inverter in its product range that is compatible with the US2000C, US3000C, and US5000 batteries.

On the other hand, there are some single-phase inverters that are compatible with these US Low Voltage storage systems from Pylontech, including devices from Sofa Solar, GoodWe, and Solis. Not to forget, all devices from the Dutch manufacturer Victron Energy are compatible with Pylontech US storage systems.

For this reason, we also have all these single-phase devices available in sufficient quantities from our warehouse in Schladen.

Advantages of Pylontech US storage systems:

- Low price

- Solid and durable technology

- 95% discharge capability

- Built-in Battery Management System (BMS)

In a conventional high-voltage battery, an external BMS is always required, which costs an additional 700-1000 €. Read on to learn more about the differences.

Important:

Not compatible with Pylontech are all inverters from the Chinese

manufacturer Growatt

. There has been no common protocol for several years, so fundamentally all

Growatt inverters

and all

Pylontech storage systems

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For more information, please visit connecting single phase inverter to three phase.

are not compatible.

What is a Phase Imbalance?

Phase imbalance

The limit for maximum phase imbalance in the power grid in Germany is 4.6 kVA. This value is defined in the VDE-AR-N 4105 (Technical Rules for the Connection of Customer Systems to Low Voltage Networks).

Advantages and Disadvantages of Low Volt and High Volt Storage Systems:
The difference between a Low-Volt (low-voltage) storage system and a high-voltage storage system is mainly in the voltage level at which they operate.

Low-Volt Storage:
A Low-Volt storage system typically operates at lower voltages, typically around 48 V, sometimes even lower. Battery modules are connected in parallel, which maintains the voltage while increasing the current. Low-voltage storage systems are typically used with single-phase inverters up to 4.6 kVA AC output power.

• 
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  They are often more cost-effective than high-voltage storage systems since a Battery Management System (BMS) is typically already built into the storage system.

  It's easy to achieve when connecting storage systems in parallel.

  
   

• Low voltages in a Low-Volt storage system can help reduce safety risks.

  The risk of electric shocks or injuries from touching the battery is lower than with high-voltage storage systems.

  
  

High-Voltage Storage:
A high-voltage storage system operates at higher voltages, often in the range of 200 V to several hundred volts. The battery cells are connected in series. They additionally require an external Battery Management System.
High-voltage storage systems are typically used in larger solar installations with 5 kWp or more solar module capacity.

• Wiring high-voltage storage systems is easier due to smaller cable cross-sections, but it can also be slightly more dangerous due to higher voltages.

• Due to the higher operating voltage and associated lower currents, high-voltage storage systems can be more efficient with smaller cable cross-sections. Larger low-voltage storage systems may require an increase in cross-sections with multiple cables, for example.

• High-voltage storage systems are typically more expensive for smaller PV installations because the storage elements need to be connected in series, often requiring an additional external

  BMS (Battery Management System)

  .

  
   

You can view our range of low-voltage storage systems at the following link:
                                 Affordable Battery Storage | inutec (inutec-int.com)

Of particular note are the BYD High-Voltage Storage Systems, which are compatible with numerous inverter manufacturers such as Kostal, GoodWe, Fronius, SMA, Sungrow

by

I love three-phase solar inverters.

If your home has a three-phase supply and you do not want or need micro-inverters then my recommendation is to use a three-phase solar inverter over a single-phase model.

What the hell is a three-phase solar inverter?

A three-phase solar inverter  takes DC electricity from solar panels, chops it up and sends it out as AC electricity shared across a three-phase supply.

They cost about $300 more than the equivalent single-phase solar inverter, but look the same:

 

What the hell is a three-phase supply?

Most homes in Australia have a single-phase electricity supply. This means that they have one live wire coming in from the grid.

 

A three-phase home has 3 live wires coming in from the grid.

This means three-phase homes can pull more power from the grid.  Handy for particularly big loads such as a:

• large air conditioner
• pool heater
• spa
• sauna
• electric car charger
• etc.

And of course a three-phase supply means you can send much more solar energy back into the grid compared to single-phase (three to six times as much depending on your local DNSP rules).

How do you know if you have a three-phase supply?

Carefully (don’t touch anything!) look in your switchboard. Count the ‘poles’ on your main switch or meter isolator. If you have single-phase you’ll only have one. Three-phase homes will have 3 like this:

 

What are your options if you have a three-phase supply and want solar power?

If you have three-phase supply you can have either:

• A single-phase solar inverter
• Microinverters
• A three-phase solar inverter

Any of these choices are valid. It will not affect how you are billed for exports or how much solar energy is self consumed.

But, I still recommend a three-phase solar inverter.

Why do you recommend a three-phase inverter?

Spreading the inverter capacity across the three wires coming into your home means that you don’t have to push the solar energy as hard to get it out to the grid. You’ll be increasing the local grid voltage less than a single-phase install and you’ll have less throttling or tripping off due to over-voltage issues. That means more solar power production with our high-voltage plagued Australian grid.

Voltage rise related solar issues are one of the biggest problems we see with installed solar power systems. I go in to detail on the causes and solutions for voltage rise issues here.

So to reiterate for the blog post skimmers:

If you have a three-phase supply I recommend getting a three-phase solar inverter. Why? Because it drastically reduces the chance of having voltage rise issues.

But not everyone agrees with me on this.

There is one downside to using a three-phase inverter other than the extra cost (expect to pay $300 to $500 more compared to a single-phase inverter). Three-phase solar inverters do make it much more expensive to have ‘Apocalypse Proof Battery Backup™’.

What is Apocalypse Proof Battery Backup?

My definition of regular battery backup is this: when the grid goes down your battery system powers some specially selected ‘essential circuits’. If the battery gets drained during the blackout, your home will black out too. In this configuration, the solar panels cannot charge your battery without the grid.

My definition of Apocalypse Proof Battery Backup : when the grid goes down your battery system powers some specially selected ‘essential circuits’. But if the sun is shining the solar panels help power your home and recharge the battery too. If you are careful with your consumption, you can carry on indefinitely charging the batteries with the sun by day and using the battery at night.

Why a 3-phase solar inverter makes Apocalypse Proof Backup very expensive.

If you have a three-phase home with a single-phase solar inverter (or microinverters) then, with the right battery – such as a Powerwall 2 – Apocalypse Proof Backup is easy and can be done out of the box:

When the grid goes down in this configuration the battery system isolates the house from the grid (islands) and keeps 230V on the ‘black’ phase so the solar inverter does not shut down. The solar panels continue to send power to the house and battery. The solar inverter is throttled using frequency shifting if there is ever more solar power than the house and battery can handle.

But if you add a battery to a system with a three-phase solar inverter it is more complicated. If the grid goes down you need to keep 230V on all three-phases to stop the solar inverter shutting down. A battery with a single-phase battery inverter (such as a Powerwall 2) cannot do this. You will be able to have ‘regular’ backup – but once the batteries are drained you’ll have no power until the grid comes back.

The solution to this is expensive. You either need a three-phase battery inverter – and if you know of one please let me know in the comments – I’ve never seen one for sale. It would look like this:

Or you have 3 batteries and battery inverters – one on each phase. But again – I don’t know of any battery systems that can play nice with a separate three-phase solar inverter. The Powerwall 2 cannot work in this configuration. Yet.

Or of course you could swap your three-phase solar inverter out for a three-phase hybrid inverter and DC Couple your battery:

But all these options are very expensive. So if you are choosing between a three-phase solar inverter and a single-phase solar inverter/microinverters the question you have to ask your self is:

What’s more important to you? Apocalypse Proof Backup™ or stable solar generation?

In my humble opinion it is better to have a system that operates well 99.9% of the time (when the grid is available) over one that operates really well 0.1% of the time (when the grid is down).

But perhaps your grid electricity goes down much more than that and getting through long outages is your priority. In that case you may want to install a single-phase solar inverter on your 3-phase supply.  Just make sure that your installer checks your local grid voltage and voltage rise before you get solar installed. And hope that your local grid voltage stays low in the future.

You could also install a three-phase hybrid inverter instead of a three-phase solar inverter. But bear in mind that any future battery must be compatible with that inverter – often that is only 2 or 3 battery models and they may be obsolete by the time you decide to buy them.

So choose wisely three-phase dweller. And do the right thing based on your local grid voltage, your local grid reliability and above-all your zombie tolerance.

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