UPDATED - August 2019
SolarEdge Technologies is one of the world’s fastest growing solar inverter manufacturers and currently ranked as the third largest inverter manufacturer globally behind Chinese electronics giants Sungrow and Huawei. The company with headquarters based in Israel supplies a wide range of inverters for residential, commercial and small utility-scale solar installations, along with a range of optimisers and smart energy solutions.
Founded in 2006 SolarEdge is rather unique among Inverter suppliers as they do not manufacture conventional string solar inverters but what the company refers to as ‘intelligent inverter systems’ using power optimisers to maximise power generation at the individual panel level.
SolarEdge systems have long held a large market share in the US but only recently has popularity started to surge in Australia. European sales have also grown rapidly as both customers and installers realise the benefits of individual panel level monitoring to help reduce the impact of shading and performance issues. Despite the higher upfront cost and added complexity, many installers are pushing the advantages of optimised systems due to the many advantages explained in detail below.
New SolarEdge products on show at InterSolar 2019
SolarEdge unveiled a large range of new smart energy products at InterSolar Europe 2019 including a new suite of StorEdge energy storage solutions. The biggest surprise was the all new SolarEdge residential battery option and larger scale modular commercial battery storage system due to be released early 2020. After purchasing the established battery manufacturer Kokam in 2018, SolarEdge have been hard at work developing a new 10kWh home battery system based on the Kokam Lithium (LFP) cells, along with a modular, rack mount, commercial battery storage system.
Also on display at Intersolar was the smart panel, a 300 Watt SolarEdge branded 60-cell panel with factory attached power optimsier. The panels manufactured by Jinergy in China use monocrystalline PERC cells and come with a 12 year product warranty, and 25 year performance warranty. Supplying a panel with matching optimiser enables SolarEdge to offer a complete solar solution. This simplifies both sales & service through having a common supplier for all components and also helps reduce complexity and installation time. The SE smart panels were first trialed in Australia with almost instant success and will now be distributed globally. See Smart solar panel specifications.
A new slightly more efficient 310W smart panel is now also available.
How the SolarEdge System Works
Traditional string solar inverters convert DC power from one or more strings of panels to AC, which depending on the numbers of panels and several other factors, results in a wide range of operating voltages. The string inverters track the voltage and convert the DC to AC at the maximum power point (MPP) of the entire string. This generally works very well unless there is partial shading, dirty cells or issues with one or more panels which results in the whole string power being reduced.
SolarEdge Inverters on the other hand operate at very specific voltage point (typically 380V). They work by using DC power optimisers connected to each solar panel. The optimisers work much like a maximum power point tracker (MPPT) and can either boost or reduce the panel voltage to deliver the required voltage to the inverter. If several panels are shaded or under performing resulting in low voltage or current, the other panel optimisers can compensate (up to a point) for the poor performing panel and provide the optimum string voltage.
SolarEdge optimisers are in effect DC to DC converters which work together to deliver the optimum string voltage to the inverter for maximum power.
Of course there are some limitations to the SolarEdge system. For example, if multiple panels are shaded or under performing the optimisers can only compensate so much (as they have a limited range) before whole system performance is reduced. I should also mention power optimisers cannot generate additional power during bad weather or when most of the panels are dirty, or shaded, sorry they aren’t magic!
solarEdge Power Optimisers
Optimisers along with micro-inverters are generally known in the industry as MLPE or Module Level Power Electronics, which as the name suggests consists of electronic power conversion units attached directly to individual solar panels. MLPE offer a range of benefits including panel level monitoring to provide real time power generation data from every panel in a solar array. Using this technology under performing panels can also be highlighted and assessed for issues.
Due to the vast array of different solar panels available on the market with different power ratings from 250 to 450 Watts and various operating voltages SolarEdge has also produced a wide range of optimisers designed specifically for different types of panels and installations. See the full details here
Below is the SolarEdge system monitoring platform which enables tracking and monitoring of every individual panel in the system. The below example shows a 18% delta between the highest and lowest performing panel. While this roof would appear to suit a string system, the weaker panels on the array would lower total performance. This is one of the advantages of panel level monitoring and power optimisation.
Range of Solar Inverters
The compact HD wave residential inverters are available in a large range of sizes from 2.5kW to 10kW (single phase). Like most inverter manufacturers SolarEdge has followed suit and removed the display screen to help increase lifespan and reduce faults. The range of larger scale 3-phase commercial inverters keeps growing with a wide range of inverters from 15kW through to 82.8kW and larger 100kW units in the pipeline.
Residential Inverter Range
Single phase from 2.5 to 10.0kW - HD wave - Data sheet
3-phase range from 5.0 to 8.0kW (New) - Data sheet
StorEdge battery interface for self consumption - Data Sheet
Commercial Inverter Range
StorEdge Hybrid battery Inverters
The StorEdge inverters, available in 3 sizes, 3kW, 5kW & 6kW, are all-in-one hybrid inverters designed for maximising solar consumption through storage and self-use, plus provide backup power to essential circuits in the event of a blackout. The peak backup power ratings are respectable at 4.9kVA and 6.6kVA, higher than most of the competition. (But keep in mind it may be lower depending on the battery output power rating). Like most hybrid inverters, the StorEdge inverter is suitable for providing backup during short, infrequent blackouts. It is not suitable for off-grid installations.
See the StorEdge Inverter specifications datasheet here. For non back-up battery installations the LG RESU-H battery range can also be used in conjunction with the HD Wave Inverter using the StorEdge battery interface.
New StorEdge Inverters
The new generation single phase StorEdge hybrid inverters, based on the HD wave technology, were on show at InterSolar 2019 along with the first 3-phase StorEdge Inverter. The new compact lightweight single phase hybrid inverters will be compatible with the LG chem, BYD and the new SolarEdge battery system still in development. New StorEdge inverters release date is mid 2019.
New AC Coupled StorEdge Backup Inverter - A modified version of the StorEdge inverter is now available (with PV disabled) as an retrofit AC coupled option to suit some specific network requirements. Available in 3.0 and 5.0kW sizes.
Benefits of Power Optimisers
Shading is one of the most common problems with standard string inverters and rooftop solar installations. However, with an optimised system if one or more panels is even partly shaded the optimisers bypass or compensate for the shaded panel/s without effecting the output of the other panels in the string.
Besides shading there are many other reasons (listed below) why individual panels or strings can underperform or reduce performance. Even minor issues can become more problematic over time as PV systems age and can develop hotspots due to individual cells degrading at different rates. Different panel degradation rates (typically 1-2% in the first year and 0.4% per year after) can result in 5-6% mismatch over life of the system.
Listed below are main factors which can result in reduced system performance on old or newly installed systems.
Shading – Trees, buildings, poles, wires, antennas, or rooftop structures
Panel mismatch – manufacturing tolerances
Panel damage – micro cracking, hot spots or water ingress
Temperature difference – thermal mismatch at different times of the day
Soiling – Dust, snow, bird droppings or birds
PID – Potential voltage and current leakage issues
PID issues in particular can be very difficult to assess without using expensive specialised equipment, however with the aid of individual panel level monitoring the SolarEdge system makes it much easier to identify Potential Induced Degradation issues as they develop.
Additional Optimiser Benefits
The SolarEdge system offer additional benefits to solar installers in regards to flexibility in design layouts as described below. One important benefit is when it comes to replacing old or faulty panels on systems in the future it is often very difficult to find the same size or model panel, optimisers overcome this as they can function will multiple panel sizes and models on the same string. For example you can replace an old 260W panel, which are no longer available with a 300W panel, and each panel will still operate at its maximum power point.
Added benefits of SolarEdge Optimisers
Multiple orientations one on string
Different panels on one string – ideal for upgrading old systems
Maximise roof space – shading in winter less of an issue
Can install parallel strings of unequal lengths
Monitoring at the individual panel, string and inverter level.
Remote troubleshooting via the monitoring portal
In addition to the individual panel level monitoring and power optimisation, SolarEdge optimisers offer a great safety advantage by reducing the DC cable voltage to 1 volt per panel in the event of a grid or inverter shut down. Strings of solar panels can be dangerous (during the daylight) as the DC voltages are usually 300-600 Volts, which can be hazardous in the event of a fire or an emergency.
High DC string voltages in combination with damaged connectors, faulty isolators, water ingress or corrosion can potentially lead to an arc fault resulting in a severe damage to the panels or in the worst case a rooftop fire. SolarEdge inverters also incorporate built in art fault detection (UL1699B) to help mitigate the chance of arcing.
Added safety - during installation and commissioning, before the inverter is switched on, the voltage is reduced to a safe level with the DC string voltage corresponding to the number of panels in the string. ie. 12 panels = 12 volts DC.
Disadvantages and Potential Problems
Installing optimisers adds to the total system cost due to the additional components required and more complex installation, with additional cables & connection points. Also more connection points could potentially lead to more failure points, especially if the right type of connectors are not used. However SolarEdge and many solar installers claim the benefits of panel level monitoring, added DC safety, and power optimisation outweigh the additional setup cost and complexity.
Having individual power electronics mounted on each panel could potentially increase the likelihood of failures and technical problems over time as the optimisers are located on the rooftop in extreme conditions such as high temperatures and humidity.
A higher than average failure rate of rooftop optimisers has been noted by some Australian installers located in the tropics or area’s with very high humidity. Despite this the overall failure rate reported by both SolarEdge and the installers we have surveyed has been low.
With the added benefits of individual panel monitoring any issues can be identified as SolarEdge also monitor all network connected systems globally. In theory this means any warranty issues should be very easily handled and resolved, so long as the system has been installed correctly.
Problems with small systems and excessive shading
Since SolarEdge residential inverters operate at 350V DC (380V for the HD wave) and the optimisers have a limited voltage range (60V to max 85V for P505) a minimum string size of 6 to 7 modules is required. Smaller systems with shading issues can be very problematic. If many of the modules are shaded the system voltage will drop out of the inverters voltage range resulting in poor performance, so generally installations with excessive shading will not be suitable for small systems with less than 8-10 panels.
Despite the ability for optimisers to mitigate the effects of shading, if a high proportion of panels in a string are shaded, then total output will be significantly reduced, or worse the inverter may shutdown if the voltage drops below the required voltage (380V).
This can also be a problem for small systems with multiple orientations. For example a split North and West roof where the West facing modules are shaded during the morning can drag down the North modules resulting in low performance. To help reduce issues associated with shorter strings and shading the SolarEdge P404 and P505 optimisers have a higher voltage range and will help when designing layouts for difficult installations. See optimiser specification sheet here.
Difficulties with 3-Phase Residential Systems
Applicable to Australia only due to the 600V limit for residential systems.
Due to the added complexity and skill required, solar Installers using SolarEdge products should be certified and trained by SolarEdge to ensure the systems are designed correctly and perform as expected.
SolarEdge Monitoring Portal
Like most solar inverters on the market, SolarEdge offer a free cloud based system monitoring portal which provides solar generation and consumption monitoring (with an additional energy meter). However unlike most others the solarEdge portal can also offer detailed panel level monitoring (provided it is enabled), plus a suite of smart home control features which can be used to control home appliances and specified loads with the additional SolarEdge smart energy products.
SolarEdge design Tools
SolarEdge have a range of free tools to help installers and designers with configuring and designing SolarEdge systems. The SolarEdge site designer helps ensure the correct optimisers and inverters are used and will operate with the selected solar modules. This tool also helps produce accurate solar performance estimates to ensure the system meets the customers requirements.
SolarEdge offer a 25 year warranty on all power optimisers and an industry leading 12 year warranty on all inverters with optional extensions of 20 or 25 years. Of course a warranty is only useful if the company is around in the future to support it and SolarEdge is doing rather well so this would not be a problem.
Some of our solar professionals have noted warranty claims can be problematic with SolarEdge and generally take longer to resolve than other manufacturers.
See warranty certificate here
Wrap up - Summary
SolarEdge inverters and optimisers will improve performance slightly over common string inverters but more importantly the SolarEdge system offers the additional benefits of individual panel power optimisation and monitoring. Optimisers can offer more flexibility in design and panel layouts especially with complex rooftops or when partial shading is a concern. However smaller systems with less than 7-8 modules, or sites with severe shading issues are generally not compatible with the solarEdge system.
Although the initial setup time and installation cost is slightly higher compared to string inverter systems, the wide range of benefits including shade tolerance, layout flexibility, simplicity in finding/replacing faulty panels, PID detection, and panel level optimisation and monitoring over the life of a system should make life easier for both installers and customers alike.
The low ‘reported’ failure rate, 12 year inverter warranty and 25 year optimiser warranty make it's easy to see why SolarEdge optimised systems are surging in popularity around the world.