The title for best grid-tie solar inverter has never been closer as many of the top manufacturers release advanced new models with clever online monitoring and smart grid capabilities. The hype around home battery systems has also been huge but it is early days for batteries with most solar installations still needing a dedicated solar inverter. Even the much anticipated Tesla Powerwall 2 with its inbuilt inverter requires a separate solar inverter to work with a solar array.
This review is focused on string solar inverters which use a string of solar panels linked together in series. These are the most common type of inverter used in Asia, Australia and Europe. Micro inverters are also popular, especially in north America, and although slightly more expensive they do have some advantages over string inverters. Learn more about micro-inverters here.
Basic layout of a string solar Inverter system
The solar inverter is the most sophisticated part of any grid-tie solar system and unfortunately it is also the part most likely to have issues. This is not surprising considering string inverters are usually located outside under harsh weather conditions including rain, humidity and extreme heat, all while generating thousands of watts of power for up to 10 hours a day. This is why it's important to use a quality inverter and mount it in a sheltered location if possible.
Due to the harsh environmental conditions it is likely that many inverters will experience a fault at some point during their lifetime, which should be 10-20 years. Solar panels can also develop problems over time which can result in poor performance but unlike a faulty inverter this will generally not result in complete system shutdown. With this in mind it is worth while paying the additional cost for a reputable manufacturer (one which has been in good business standing for 5+ years and with extended warranties if available.) SMA has ranked on top of the list for many years due to the low failure rates and high quality service as they usually ship replacement units in 3-5 business days. Many of the lesser known 'value' brands will only repair a faulty unit if it is shipped to them (at the owner costs) and returned which often takes several weeks and sometimes months. This will have a much greater financial impact due to system downtime.
- Quality & Reliability
- Service & Support
The above criteria was used to determine the best solar string inverters available on the market together with continuous feedback from solar installers and industry specialists. Note this comparison is focused on the common grid-tie solar 'string' inverters (single phase) although the larger commerical 3-phase inverters from the same manufacturers are equally well regarded.
TOP FIVE SOLAR INVERTERS 2017
Fronius - Primo & Galvo range
SMA - New Sunny boy range
Solaredge - SE range & HD wave
ABB - New UNO range
SolaX Power - New X1 range
One of the biggest surprises among the previous top inverter manufactures was the decision by Bosch to pull out of solar altogether. The Bosch solar inverters were impressive with a high build quality and unique features so the reason behind Bosch's decision to pull out of solar is unknown.
Another surprise was the decision by SMA to manufacture the new range of sunny boy AL & AV inverters in China. SMA was traditionally the standard against which other inverter manufacturers were measured so it will be interesting to see how the new SMA inverters hold up to the competition. This may prove more difficult as SMA has also taken the risky move of not including a display panel on the new inverter range and instead relying on wifi communications for setup and monitoring.
At present there are only four 'Premium' inverter manufacturers on the market - SMA, Fronius, SolarEdge and ABB.
SolaX Power is a relatively new Chinese manufacturer and as yet only produce value level inverters, although the new model range soon to be released could move them closer to the premium level.
Fronius Inverters have surged in popularity since the release of the snap-in design around 2 years ago. The high-end Austrian manufactured inverter range has definitely become the inverter of choice for many domestic and commercial solar installations. Although customers are also raving about the performance and monitoring features, plus the reliable customer service from Fronius in Australia. Although the high demand for these premium inverters has resulted in some supply issues and quality problems were recently raised possibly due to rushed testing/inspections during manufacture. Although any issues have been promptly corrected, and with the 10 year extented warranty period the Fronius range is now considered the industry leader.
One of the clever features is the integrated solar DC isolator which means an external isolator box is not required, resulting in a much neater installation. Also the unique snap-in design makes servicing and installation very simple.
Wifi monitoring comes standard with all inverters via the Fronius Solar.Web. The addition of a separate Fronius Smart meter enables monitoring of energy generation and consumption and can be used as a complete home energy monitoring system. A free solarweb smart phone app is also available for android of iOS.
See full Inverter specifications here
SMA inverters now made in China! Leading German manufacturer SMA Solar Technologies recently transferred some manufacturing from the US and South Africa to China, although they have retained the head manufacturing plant in Germany. SMA inverters have a proven track record for reliability and are generally considered one of the highest quality inverters available, however this decision to move manufacturing to China has led to some doubts about the ongoing quality. Manufacturing a product in China is not always to the detriment of quality as long as the correct testing and quality control measures are implemented. It's early days but this move has already effected SMA's reputation to some degree, although some argue this will enable SMA to produce the new generation AV sunny boy inverters at a more competitive price while still maintaining the level of quality expected. Despite the manufacturing location, local service and support is very reliable and SMA provides an optional extended 10 year warranty.
Another controversial decision was to eliminate the display panel from the new inverter range and rely solely on the wifi communications. A digital display in an outdoor environment can be problematic so this my reduce faults and warranty issues in the long term, but only if the communications is very reliable and stable.
The new Sunny boy AV inverters have no display for setup and monitoring so reliable communications will be vital to the success of the new models.
SMA also has one of the best free monitoring software packages available known as the sunny portal. Since the new Sunny boy inverters have no display for setup and monitoring, reliable communications will be vital to the success of the new models. Most SMA inverters have the wifi webconnect capability as standard and with the additional Sunny home manager 2.0 (energy meter) a complete, easy to use home energy monitoring system can be created. Note the sunny portal mobile app (android) is not a great effort with no real time data available so SMA have some work to do here.
See full Inverter specification here
SolarEdge inverters (SE range) manufactured in the US are relatively new to Australia. This popular inverter stormed into the Australian solar market along with the first Tesla Powerwall battery in early 2016. Since the Powerwall was a unique 'high voltage' battery the StorEdge model was the only compatible (hybrid) inverter for single phase homes. Since the vast majority of Australian households are single phase the unique inverter was the obvious choice for most installations.
The recently released new HD wave (SE-H series) is possibly the smallest inverter on the market and according to the specifications is also the most efficient at 99% for the larger 5 - 6KW models. This new generation inverter uses advanced thin-film capacitors and digital processor to produce a clean AC output with low losses. All SE inverters only function in combination with additional DC optimisers (see below) which perform part of the job of a common string inverter so this is perhaps the reason Solaredge was able to package such a small efficient inverter.
The biggest advantage SolarEdge has over the competition is panel level monitoring through the use of ‘DC optimisers’.
DC Optimsers are small electronic modules attached to the back of the solar panels which allow for individual panel level tracking and monitoring. Previously individual panel monitoring was only obtained through the use of micro-inverters, plus some add-on optimisers such those from Tigo. This is a clever add-on feature does add to the cost and complexity of the system and may have the potential to cause issues or faults in the longer term.
Panel shading a problem? For complex roof profiles or installations with shading issues this would be the inverter of choice.
SolarEdge also has an industry leading 12 year warranty period.
SolarEdge inverters have 'optional' wifi which together with the optimisers provides power output data of each panel individually, which is great for both monitoring and fault detection. Also SolarEdge definitely have one of the best smart phone apps for remote system monitoring.
See full Inverter specification here
ABB is a premium manufacturer but many installers we interviewed consider the ABB PVI range to be outdated and have highlighted slow and substandard customer service compared to the top three, however it is still rated higher than the value brands and offers some advanced features. Also since ABB is an industrial giant you can be sure they will be around in the future in case of warranty/service issues. Although the below standard reputation may be reversed with the recently released new range of UNO-TL and UNO-TL-DM-PLUS single phase solar inverters. However service and support with any faults or warranty claims will be vital to the success of the new UNO range.
The new UNO inverters have the common plug & play interfaces, are lighter, more compact and offer a unique backup AC supply in case of a blackout (TBA). It is not yet known how this works without a battery but it may be a very clever innovation.
ABB are not well known for their monitoring capabilities but have recently released a new Wifi logger card (VSN300) which can be installed on all UNO and TRIO (3-phase) inverters. The new UNO-DM-PLUS inverter range has wifi as standard and offers some advanced features for smart home and smart grid applications (zero feed-in). Hopefully they include the wifi logger on all models in future.
5. Solax Power
SolaX Power are a relatively new solar inverter manufacturer which was largely unkown in the industry until they launched the economical battery X-hyrbid inverter. SolaX is a subsiduary of the the much larger Suntellite Group in China which manufactures solar cells, panels and inverters, and has a strong emphasis on research and development which is possibly why they have managed to produce quality inverters with advanced features compared to many other lower level manufacturers. SolaX Power also has a strong global presence with an Australian support office located in Melbourne. The current X1 range of solar inverters do not have the sleek designs of the european rivals but at close to half the price you wouldn't expect them to compete on this level, their slogan sums them up nicely 'simple, reliable, efficient'.
One of the clever inverter options from SolaX is the very affordable X-hyrbid unit which is one of the most economical battery ready solar inverters available. Despite the economical pricing the new range of Solax power inverters due to be released soon do look more impressive and may even put some pricing pressure on premium inverters above.
The Solax online monitoring portal V2 is quite advanced and offers access via smart phone apps or web interface with battery management features for hybrid systems and email reporting, although the wifi dongle is an optional extra.
See full Inverter specification here
Best value Solar Inverters
Although this article is focused on the high-end or premium inverter brands (exc Solax), it is worth highlighting some of the better value inverter brands that are well known and still improving/developing their products. Several of these manufacturers are quite reliable and are often only let down by the lack of service and support when an issue occurs.
Delta is generally well regarded by installers as one of better value Chinese made inverters. This is not surpising as Delta Group is a gloabal electronics giant which has been manufacturing power control systems around the world since 1971. Although the new RPI range released a few years back does not seem to have become a huge hit with installers, possibly due to the the tough competition from the many other lower cost inverters manufacturers. With a 10 year product warranty as standard and an Australian office located in Melbourne, it is still one of the more trusted value level inverters available.
GoodWe is a large, well known Chinese inverter manufacturer established in 2010. Goodwe like most Chinese brands have a mixed reputation in Australia due to some previous quality issues, but have improved considerably over the last 2 years. The Goodwe hybrid inverter ( GW5048D-ES) is a standout product from the Goodwe range and is well regarded in the industry with many other manufacturers incoporating this inverter into there own home battery energy storage systems (ESS). All Goodwe inverters include Wifi monitoring as standard.
Sungrow is one of the oldest Chinese solar inverter manufacturers but is not well known in Australia. It is a very large player internationally and has a reasonably good reputation for reliability compared to many other value level manufacturers. Sungrow produce one of the best value hybrid solar inverters on the market - the SHK5 ESS model inverter is known as a reliable and affordable option for home battery systems when back-up power isn't a priority. Sungrow inverters include Wifi monitoring as standard on all residential models.
Zeversolar (see full review here) is one of the largest inverter manufacturers in China and is almost solely owned by SMA. Since the purchase in 2013, SMA have been working closely with Zeversolar to improve the manufacturing quality and reliability. However it is taking time to improve as installers are still reporting issues with the new range released in 2015. In addition generally slow support from the service centre has not helped Zeversolar's reputation.
Growatt New Energy Technology Co was established in 2010 in China. Growatt inverters have had some regular problems but are one of a few Chinese manufacturers to have an Australian based service centre so they are generally quick to replace any faulty units still covered under the standard 5 year warranty. In addition an extented 5 + 5 year (10 year) warranty is sometimes available depending on installer and inverter model.
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