SolarEdge Technologies is one of the world’s fastest growing solar inverter manufacturers and currently ranked as the third largest inverter manufacturer globally behind the German owned SMA and Chinese electronics giant 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 energy storage 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.
In Australia which currently has over 1.7 million rooftop solar installations the popularity of SolarEdge inverter systems has grown rapidly as both customers and installers realise the benefits of individual panel level monitoring to help prevent and troubleshoot faults or performance issues. Despite the higher upfront cost many installers are pushing the advantages of optimised systems as they can also provide a greater level of flexibility in layouts in addition to slightly higher generation over the life of the system.
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 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 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 and they do this by using power optimisers connected to each solar panel to supply the optimum voltage for maximum power generation. If a panel is shaded or under performing resulting in low voltage or current, the other optimisers can bypass or compensate for the poor performing panel to provide the optimum voltage to the inverter.
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 all the panels are dirty, 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 be highlighted quickly 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
Several solar panel manufacturers supply panels with embedded SolarEdge optimisers which mean the installation is much neater and simpler. LG energy, JA solar, Jinko solar and Canadian solar all offer SolarEdge optimiser embedded panels.
Range of Inverters
SolarEdge manufacture a wide range of residential and commercial inverters for different applications. The new generation compact HD wave residential inverter offers advanced features made with high quality long lasting components such as ceramic thin-film capacitors and silicon switches.
Residential Inverter Range
- Single phase from 2.5 to 6.0kW - HD wave - Data sheet
- Single phase from 8.0 & 10.0kW (coming soon)
- 3-phase range from 5.0 to 8.0kW (New)
- StorEdge Hybrid inverter 5.0 & 6.0 kW - Data Sheet
- StorEdge battery interface - Data Sheet
Commercial Inverter Range
Battery storage - StorEdge Hybrid Inverter
The 'StorEdge' residential hybrid inverters are compatible with the well known LG Chem RESUH (high voltage) batteries available in two sizes, the RESU7H battery at 6.5kWh capacity and the RESU10H at 9.3kWh usable capacity. Due to high demand LG chem have been working closely with SolarEdge and are due to release (mid 2018) an add-on combiner/junction box to enable 2 x RESUH batteries to be connected for greater energy storage capacity up to 18.6kWh.
The StorEdge inverter available in 2 sizes, 5kW & 6kW is an all-in-one hybrid inverter designed for maximising solar consumption through load shifting (self-use) and can provide back-up power to essential circuits in the event of a blackout. See full specifications. For non back-up battery installations the LG RESUH battery range can also be used in conjunction with the HD Wave Inverter using the StorEdge battery interface.
Benefits of Optimizers
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 Optimizer 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 is no longer available with a newer 285W panel with each panel operating at it 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. Normal strings of solar panels can be dangerous (during the daylight) as the DC voltages are usually 300-600 Volts which can be very hazardous in the event of a fire or 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 many 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. Also salt mist corrosion near seaside homes or buildings would generally not be a great combination with roof mounted electronic systems. However the failure rate reported by both SolarEdge and Australian installers we have surveyed has been low, and with the added benefits of individual panel monitoring any issues can be identified immediately as SolarEdge also monitor all network connected systems globally. This means any warranty issues should be very easily handled and resolved.
Problems with Smaller Systems
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 severe 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.
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.
Due to the added complexity and skill required solar Installers using SolarEdge products should be certified and trained by SolarEdge to ensure the systems perform as expected.
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.
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 very well so this would not be a problem.
See warranty certificate here
Wrap up - Summary
SolarEdge inverters and optimizers will improve performance slightly over common string inverters but more importantly the SolarEdge system offers the many benefits of individual panel power optimization and monitoring. Optimizers offer more flexibility in design and panel layouts especially with complex rooftops or when shading is a concern, in this way optimizers make it possible to add solar to sites which would otherwise have extremely poor performance and would not be suitable using common string inverters. However very small systems (less than 7 modules) with 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, easy system trouble shooting, simplicity in finding/replacing faulty panels, PID detection, easier warranty claims, and panel level optimisation and monitoring over the 25+ year life of a system will no doubt make life much easier for both installers and customers alike.
The low reported failure rate, 12 year inverter warranty and 25 year optimiser warranty makes it's easy to see why SolarEdge optimised systems are surging in popularity around the world.