The title for the most popular grid-tie solar inverter has never been closer as many of the top manufacturers release advanced new models with intelligent online monitoring and smart home energy management features. Home energy storage systems or hybrid systems is also growing, but it is early days for batteries and the majority of solar installations still require a dedicated solar inverter.
Solar Inverter Function & Problems
The solar inverter is the most sophisticated part of any grid-tie solar system and unfortunately it's also the part most likely to have issues. This is not surprising considering inverters are usually located outside in 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 extreme variations in humidity and temperature, it is likely that many inverters mounted outdoors will experience a fault at some point during their lifetime. However, the life of a solar inverter can be significantly increased by locating it inside a garage, under a carport and out of direct sunlight.
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 more than 5 years and with extended warranties if available.)
Warranty and Service
Fronius and SMA have ranked on top of the list for many years due to the low failure rates and great service, as we are able to get it locally in Singapore. Fronius available with 10 year warranties, while SMA offer 5 year manufacturers warranty as standard. It is similar with Huawei and Growatt. 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 weeks and sometimes months. This will have a much greater financial impact due to system downtime.
Solar Inverter Types
1. String Solar Inverter
This review is focused on 'string' solar inverters which use a string of solar panels linked together in series. String inverters are the most common type of inverter used in Singapre, Malaysia, Europe & Asia, and growing in popularity in the US where micro inverters are very popular.
2. Hybrid Solar Inverter
The new generation hybrid or battery ready inverters combine a solar and battery inverter together in one simple unit. These inverters are becoming more competitive against solar inverters as hybrid inverter technology advances and batteries become cheaper and more appealing.
3. Off-grid Solar Inverter
Off-grid or stand-alone power systems require powerful battery inverters with inbuilt chargers which can be setup as either AC or DC coupled systems. Modern, flexible off-grid inverter/chargers, also known as multi-mode inverters, can be used to create advanced hybrid grid-connected systems. For smaller scale off-grid systems, we usually are using solar charge controllers to operate solar system.
4. Micro Inverter
Micro inverters, also known as micros are very small solar inverters attached directly to individual solar panels. Since each micro inverter and panel operate independently, they are a great option for complex roof layouts and locations with shading issues. Despite the slightly higher cost, micros are very popular only in North America and the many advantages they offer over string inverters.
Inverter Rating Criteria
The following 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 commercial 3-phase inverters from the same manufacturers are equally well regarded.
Quality & Reliability
Service & Support
There is a considerable price difference between the hundreds of different solar inverters available. For example, a low-end 5kW inverter can start from as low as S$1,500, while a premium quality 5kW inverter with 10 year warranty may cost $1950 or higher. However, considering the higher failure rates of many low-end/cheap inverters and difficulty claiming warranties, we recommended you invest in a higher quality unit. As a common saying in the solar industry goes 'the cheapest product will cost you more in the long run'.
The Most Popular Solar Inverters 2020 (Top 5 Residential Solar Inverters)
Fronius - Primo
Huawei - SUN2000L
Growatt - MIN
SMA - Sunnyboy
SolarEdge - SE and HD wave
The Most Popular Commercial Inverters (3 Phase)
Huawei - SUN2000
Growatt - MAC & MAX
SMA - Sunny Tripower & Core 1
Fronius - Symo & Eco
SolarEdge - SE 3-phase