Solar inverter efficiency – how much does it matter?

It’s almost human nature to assume anything above 95% is excellent – and, it is. However over the lifetime of your solar inverter, the difference from 98% to 97% can reveal itself on your power bills. 

Efficiency is a critical specification, that is directly correlated to the production of your system, before you can utilize those solar rays in the form of AC power, an inverter must convert it, and although the core principals remain the same despite using alternative solutions such as a micro-inverter, the power must be converted. So, the higher the efficiency is, the more kilowatt-hours can be created. Simply put this may seem to be  the perfect number, the closer to 100% the better, however it isn’t always.

Solar Inverter Efficiency isn’t as simple as it looks 

Typically there will be two figures when it comes to efficiency, these will be maximum efficiency and European efficiency. European efficiency is the more reliable figure as it outlines average performance, as opposed to the highest level of efficiency possible. Unavailable to us are efficiency figures for Australia, as Europe is very different in terms of conditions, but that is not possible. This leaves us in Australia will slightly less accuracy, however, they are the best indicator available. 

What do the numbers look like?

For the purpose of this article we won’t delve too much into the other possible types of inverters, such as Hybrids or Off Grid, we will focus on the String inverters which are the most common solution. Micro inverters won’t be as efficient as string converters, so they haven’t been included below.

Popular brands for Australian solar panel systems are,

A few of the relevant scores are below, all for a 5kW Inverter,

  • Fronius Primo  5.01-1 : 97.1%
  • SMA Sunnyboy : 96.5%
  • Delta Home Series : 97.5%

Assuming these are used for a 6.6kW system, which is a popular option for larger households, the difference between a SMA and Delta inverter represents a meager 1%. If we translate that to production numbers on the Gold Coast, the difference between using a 96.5% inverter, vs a 97.5% inverter is 96kW in a year – over 10 years let’s say, that makes up a 960kW difference, or in dollars $199.3 over a 10 year span. 

Now these numbers are very far from perfect, they don’t account for a number of factors, and assume all other aspects of your solar panel system maintain in perfect working order for the next 10 years. However, it does show that it does make a difference, not only in production but in the money you spend. 

What else is important in an inverter?

While $200 Is nothing to scoff at, it’s hardly a game changer. There are many other factors that play into installers and consumers’ minds, namely how durable an inverter is. This is a tradeoff, as to increase efficiency, some short cuts may be made in durability, such as effective cooling within the inverters. Removing this, therefore removes the required energy to cool the inverter, resulting in marginally higher efficiency. 

Manufacturers will have warranties associated with their inverters which can provide some insight into the tradeoff. 10 years is considered a minimum for a lifespan, with warranties ranging to around 12 years on the high end. The higher the warranty, the more confident consumers can be in the longevity of their choice. 

When working with a solar installer, it is important to discuss most important factors to yourself. Get them to explain why they have made particular choices for equipment, as there is never a correct answer, only a choice that applies better to some circumstances. 

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Fronius Inverters / Solar Batteries Australia

Fronius (website here) were founded in 1992 and they have over 70 years of experience in battery charging technology, as well as creating their first inverter in 1995. Also known as Fronius Solar Energy, they are an Austrian based company who, in 2017, have a range of highly recommended and well performing inverters, solar batteries, and intelligent energy management software through their Solar.Web system.

Let’s have a look at some of their range and discuss how you can order Fronius products in Australia.

Fronius Inverter Product Range

Fronius Primo Inverter
Fronius Primo Inverter

Fronius stock a range of inverters for every power category – from 1.5kW – 27kW, depending on the size of your PV solar array. According to international sales director Adrian Noronho to EcoGeneration, the biggest seller in Australia is the Primo series for single-phase residential systems – and they sell over 4,500 of these units per month. Their inverter range includes:

  • Fronius Galvo / Galvo UL (SnapINverter )
  • Fronius Primo / Primo UL – this has been specially developed for private households wanting from 3.8 – 15kW – it’s a single phase, transformerless device that connects to WiFi via WLAn, has a SuperFlex design, and includes the super simple SnapINverter mounting system. The primo also has two MPPT (Maximum Power Point Tracking) controllers.
  • Fronius Symo / Symo UL / Symo Hybrid
  • Fronius Eco

The Solar.web App works on iPhone and Android so you can see how it analyses your consumption patterns, optimises your energy usage and manages how your surplus energy is stored.

Fronius Solar Battery Australia

Fronius Solar Battery
Fronius Solar Battery

Fronius also manufacture a lithium-iron phosphate solar battery which comes in 6 different sizes – 4.5, 6.0, 7.5, 9.0, 10.5, 12   (usable capacity 3.6kWh to 9.6kWh)

The batteries are rated for 8000 cycles and over 20 years long service life at an ambient temperature of 22°C. Please note that they are only IP20 weather rated so these are indoor batteries – no matter which capacity you choose they all have the same dimensions (955mm high x 570mm wide x 611mm deep) – the weight ranges from 91kg for the 3.6kWh battery to 176kg for the 9.6kWh.

Voltage range, nominal charging power, nomimal discharge power, and max charging/discharge current will vary depending on the product chosen so please double check this will be suitable for your installation before purchasing.

The inverter/battery combo is able to be DC or AC coupled using their Multi Flow Technology- so it’s suitable for grid or offgrid solutions.

If you’re not 100% sold on which brand you’d like it’d also be worthwhile checking out our solar battery comparison where you can learn more about the various other products on the market.

Fronius Energy Management

If you want to optimise an existing PV system using ‘Intelligent Energy Management’ is a great choice – its ‘Solar.Web’ monitors household energy and optimises usage based on patterns of usage. Watch the video below to learn more and feel free to contact us if you want to get the best quote for this system.

Warranty Levels

You can choose between two levels of warranty: a ‘warranty extension’ which means parts will be replaced but the user will have to pay for labour, and the ‘warranty extension plus’, which is like comprehensive insurance for your car – where, if a claim is made, in additional to all replacement parts, labour costs for transporting, removing and installing the replacements is also covered.

Please note that these warranty terms can differ depending on the country and region – we have attached the Australian/New Zealand Terms and Conditions updated as per 31.08.17.

Warranty Terms and Conditions – Australia and New Zealand

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