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Best commercial solar inverters, 20-40kW

Best commercial solar inverters, 20-40kW

Most leading solar inverter manufacturers make three-phase inverters for commercial solar installations. These range in size from 10kW to 100kW plus.

This blog reviews six of the leading solar inverters in the 20kW to 40kW category.  This size solar panel system is suitable for commercial premises using 80-140kWh a day.

Each of the six solar inverters are rated on the following criteria:

  1. Efficiency
  2. Number of MPP trackers
  3. Start-up voltage
  4. Price
  5. Warranty

On this blog:

  • What each selection criterion means
  • Summary table: how each inverter rates
  • Conclusion

What each selection criteria means


Solar inverter efficiency is a critical rating that directly impacts the performance of your solar power system.

Solar inverter efficiency measures how much DC electricity (produced by the solar panels) is converted to usable AC electricity for your business or grid export.

Every extra percentage point in solar inverter efficiency helps maximize power output and payback. A difference of a couple of percentage points in solar inverter efficiency for a large commercial system can easily translate into hundreds, or even thousands, of kilowatt hours more power over a year.

And, of course, more power means lower electricity costs – which is what every business wants!

Number of MPP trackers

MPP trackers, or MPPTs, stands for maximum power point trackers.  An MPP tracker is an efficient DC to DC converter which maximizes the power output from connected solar arrays.

The reason why MPPTs are needed is because solar panels all produce slightly different levels of voltage and current. These differences are caused by the condition of the panel, the amount of sunlight hitting it, the temperature on the roof etc.

The problem is that a series circuit can only have one value of current, which will always be based on the worst performing solar panel.

What the MPPT does is vary the resistance in the circuit to adjust the voltage and current.  This evens out the current in the circuit, resulting in more power from each circuit with a MPPT.

So, if you had a 60-panel solar power system with just one MPPT, if one of the panels dropped in output to 60%, all 60 panels would drop to 60%.  If, however you had 60 panels with 3 MPPTs, with 20 panels on each MPPT – then if one of the panels dropped to 60% output that would only impact 19 panels, the other 40 panels would continue to generate maximum power.

Essentially, the more MPPTs your solar inverter has, the more solar power you get.  So, the more MPPTs the better!

Start-up voltage

When the sun wakes up, you want your solar power system to wake up too.  But some systems are early birds, and some aren’t!

The way to make sure you get a solar panel system that gets to work early is by checking the start-up voltage on the datasheet.

What you want is a solar inverter with the lowest possible start-up voltage – that way when the sun rises and sunlight hits your panels, they start generating power immediately.


When it comes to price, you’ll find that the world’s largest PV inverter manufacturers – such as GoodWe and Sungrow – have the edge due to their economies of scale and massive investment in R&D.  Smaller, more niche European inverter manufacturers produce good products, but their cost base is higher resulting in premium prices.

In our opinion, some of the lower priced solar PV inverters from China’s largest inverter manufacturers are amongst the best commercial inverters on the market – the fact they’re cheaper is a bonus!


Most commercial solar inverters sold in Australia come with a manufacturer’s product warranty of 10 years including parts and labour.

What’s surprising, is that two of the premium-priced European commercial inverters – SMA and Fronius – only have a 5+5 year warranty.  This means you get the first 5 years covered for parts and labour, but the second 5 years is only covered for parts.

Given that labour is always the most expensive aspect of any inverter replacement, a 5+5 year warranty isn’t very attractive – particularly when you can get a full 10-year product warranty on quality commercial solar inverters from other manufacturers.

Summary table: how each inverter rates

The six top commercial solar inverters are ranked in the table below based on the selection criteria.

Best commercial 3-phase solar inverters 2022: 20kW to 40kW

Ranking Inverter Inverter capacityCompany HQEfficiency# MPP trackersStart-up voltagePriceWarranty
1GoodWe SMT Series25kW / 36kWChina98.9%3180VAffordable10 years (when registered on company’s Smart Energy Management System)
2SolarEdge SE Series



25kW / 30kW / 33.3kWIsrael98.3%Power Optimizers (each optimizer acts as a MPP tracker)340VMid to high25-years – Power Optimizers


12 years – inverter

3Sungrow SG30CX


30kWChina98.6%3200VAffordable10 years



20kW / 30kW / 33kWItaly98.4%2250V (default 430V)Mid10 years
5SMA Tripower X15 kW / 20kW / 25kWGermany98.2%3150 to 180VHigh5+5 years
6Fronius ECO


25kW / 27kWAustria98.2%1650VHigh5+5 years (if registered with Fronius)


The GoodWe SMT Series of commercial inverters outperforms the other five inverters based on its combined ranking against the five section criteria: efficiency, MPPTs, start-up voltage, price and warranties.

Coming in a close second is SolarEdge.  Because SolarEdge works differently from other solar inverters using Power Optimizers, the overall system efficiency for a SolarEdge commercial solar system can exceed that of all its competitors in many circumstances.

The reason why SolarEdge is so efficient is because each Power Optimizer is a MPP tracker – so with a 60-panel system you have 60 MPP trackers.  That’s a multiple of 20X more MMP trackers than most other commercial solar inverters.

Even though the inverter efficiency for SolarEdge is fractionally lower than GoodWe, SolarEdge will produce more power over the lifetime of the system because each panel is optimized to produce maximum power and will not be affected by underperformance of other panels.

Another plus point for SolarEdge is that their optimizers have a 25 year warranty and their inverter is the only one to have a 12 year warranty – all the rest have 10 years or less.

When it comes to start-up voltage, GoodWe is a winner.  With a start-up voltage of 180V, the only other inverter to rival it is the SMA Tripower X.

Looking at price, GoodWe is a top performer coming in with an affordable price point for commercial solar inverters in the 20kW to 40kW size category.  It also has a good warranty – 10 years parts and labour.  However, when it comes to warranties you can’t beat SolarEdge!

All up, GoodWe is a high performance commercial solar inverter at an affordable price point backed by a solid 10-year product warranty.  However SolarEdge is a very close second and offers superior power generation performance over the system lifetime due to its unique Power Optimizer technology, plus an unbeatable warranty.

Get in touch

If you’re interested in a commercial solar PV system for your business or organization, get in touch.

We have extensive expertise in commercial solar system design, installation, and maintenance for systems sized from 15kW to 100kW-plus.  Plus, we also have the commercial kudos in solar financing to get you the best ROI and quickest payback on your investment.

Act now! Every day without solar means another day that you’re paying more than you need for electricity.

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