Solar Edge, a manufacturer of inverters and power optimizers originating from Israel, is a very popular brand in the solar industry. The technology of optimizing the operation of individual modules combined with very effective marketing enabled market success.
SolarEdge in the world
Solar Edge is one of the largest inverter manufacturers in the world. The company has delivered a total of over 3.7 million inverters with a total capacity of over 31.6 GW.
The company was founded in 2006 in Israel and the first products with the SolarEdge logo were delivered to the market in 2008. Serial production started in 2010. Since 2015. Solar Edge has its own production plant in Israel, but most of the production of inverters and optimizers is contracted to subcontractors.
Solar Edge, instead of classic string inverters, offers systems equipped with power optimizers that enable individual photovoltaic modules to operate independently of each other.
Principle of operation of the SolarEdge system
SolarEdge uses power optimization at the level of a single photovoltaic module (MLPE (Module-Level Power Electronics) includes power optimizers and microwaves ). A typical string inverter controls the operation of a chain of photovoltaic modules (a chain is a group of interconnected PV panels ). If one of the modules works worse than the others (e.g. due to dirt) in a classic inverter, it will affect the entire chain. In the Solar Edge system, the performance degradation will be limited to a single module.
Operation of the shaded photovoltaic module
The junction box generally contains three bypass diodes that turn off part of the module if it is shaded. In this way, the impact of shading on the remaining PV panels in the system is limited. However, it sometimes happens that shading affects the entire chain of PV panels.
The basic task of the bypass diode is to protect the module against the so-called hot-spots, but it also allows you to reduce the impact of shadow on energy production in a photovoltaic installation.
The main difference between a system with a good-quality classic inverter and the SolarEdge system lies in the way in which the impact of a worse module on the entire system is limited. A typical inverter uses an algorithm that searches for the so-called maximum operating point of the module chain (MPPT) while in Solar Edge each module has an individual algorithm.
SolarEdge Power optimizer
Solar Edge used a different than the classic approach to the shading problem, namely by installing a device called a power optimizer under each PV module. The power optimizer means that instead of having one MPPT tracking system for a string of panels, the MPPT algorithm has been transferred to an individual PV module, which means that each photovoltaic panel produces maximum power and in shaded conditions more energy can be obtained from the photovoltaic system.
Additionally, in addition to optimizing the operating parameters of individual PV modules, the optimizer enables voltage reduction to 1 volt on the module and monitoring the efficiency of each module.
SolarEdge single-phase inverters
Single-phase SolarEdge SE2200H, SE3000H, SE3500H, SE3680H inverters are available on the Polish market. The number after the letters SE indicates the power of the inverter, e.g. SE2200H means a single-phase inverter with an output power of 2.2 kW. The letter H stands for HD Wave and denotes the generation of inverters introduced to the market in 2015. Catalog efficiencies according to the European standard range from 98.3% for Solaredge SE2200H to 98.8% for SE3580H.
SolarEdge three-phase inverters
Solar Edge offers three-phase inverters with power from 3 to 10 kW: SE3K, SE4K, SE5K, SE6K, SE7K, SE8K, SE9K and SE10K. As with single-phase inverters, the number indicates the inverter’s output power. Due to the increasing power of photovoltaic modules, Solar Edge has introduced inverters dedicated to photovoltaic installations consisting of a small number of PV modules. Three inverters are available: SE3K-RWB, SE4K-RWB and SE5K-RWB.
The reason for creating a parallel series of inverters is the SolarEdge technology, which in classic three-phase inverters requires operation with a DC voltage (voltage from the modules) of 750V.
Therefore, the minimum number of modules that can be connected to traditional three-phase SolarEdge inverters is 14 pieces. SE3K-RWB to SE5K-RWB inverters operate with a lower voltage of 375V, which is easier to obtain from an installation consisting of several PV modules.
The RWB series of inverters differs from the K series, among others: efficiency of inverters. For example, SE3K has a catalog efficiency of 96.7%, while SE3K-RWB has an efficiency of 94.6%. For comparison, the efficiency of the Fronius Symo 3.0-3-S inverter is 96.2% and SYMO GEN24 3.0 PLUS is 96.7%.
SolarEdge optimizer – principle of operation
A power optimizer is a device that increases or decreases the voltage obtained from a photovoltaic module. However, such conversion requires additional energy for the optimizer’s operation, which reduces the yield from the module. Just like communication between the optimizer and the inverter – this also requires the appropriate amount of energy.
Greater yields from a photovoltaic installation
A photovoltaic installation equipped with the Solar Edge system with an optimizer on each PV module enables, under certain conditions, increased energy production from the PV installation compared to a classic inverter. Greater yields result from:
- Factory mismatch of PV modules – PV modules are categorized according to specific power levels, e.g. a 350W module generally has a power of 350 – 355W; by connecting modules in a chain, there can be modules with a power of e.g. 350W and 355W; In practice, however, good quality modules have very similar powers, most often in the middle of the tolerance range, e.g. 352W – 353W.
- Pollution, shading and leaves. Dirt on modules reduces production.
- Uneven aging of modules – over time, the efficiency of modules decreases and this may happen at different speeds.
Photovoltaic modules cannot be turned off when the sun is shining on them. Even if we turn off the classic inverter, voltage will remain in the cables on the roof. The SolarEdge system allows voltage reduction to 1V per module.
However, it must be remembered that the installation of power optimizers involves an increased number of connections in the DC installation. A large number of connections increases the risk of fire in a PV installation, especially if connectors of different types or manufacturers are used, which may happen because PV panel manufacturers use different quick connectors.
Disadvantages of the SolarEdge system
In many cases, optimizers can increase production compared to systems without optimizers. This is especially true for complex, multi-faceted roofs or roofs with a lot of shade. For installations where there is no shade, the benefits of SolarEdge may be limited.
It must be remembered that power optimizers use energy for their own work. Unlike inverters, there is no standard that defines the so-called European efficiency of optimizers, which is why the so-called “weighted performance,” which is determined by the manufacturer. According to research conducted at the University of Zurich, it was found that the efficiency of power optimizers is usually around 96% – 97.5%.
A study conducted at the University of Southern Denmark showed that classic inverters can produce more energy than systems with optimizers not only in clear skies but also in cloudy conditions. Interestingly, in some situations the system with a classic inverter produced more energy even when the modules were in shadow.
Installing optimizers involves additional cabling, and power transmission losses increase with the length of the cables. Additionally, power optimizers require a much larger number of connectors, which also generate losses and increase the risk of fire, as mentioned earlier.
You should also remember that devices sometimes suffer from failures. Solar Edge provides a 25-year warranty for its optimizers, which does not change the fact that problems do occur with them. If the optimizer in the middle of a large area of modules is damaged, the installer must dismantle at least several adjacent modules to get to it. Due to the significant labor intensity of such work, the investor should check with the installer whether there will be any problems with replacing the damaged optimizer.
Overall, the Solar Edge system is a good solution and can provide many benefits under certain conditions. Most effective on difficult roofs with many planes and directions or when there is significant shading on the modules.
SolarEdge systems are equipped with monitoring that allows you to control the operation of the photovoltaic installation. Monitoring allows you to track the operation of individual PV modules, which may be particularly useful if they are distributed on different planes or regularly shaded. Monitoring individual modules allows for:
- Identification of modules working worse than others due to e.g. a growing tree or dirt,
- Identification of modules that degrade (reduce efficiency) faster than others,
- Identification of the module in which the bypass diode was damaged.
Perhaps one of the most significant advantages is detecting a damaged bypass diode. This applies primarily to modules that may receive intense shadow during the day (e.g., from a chimney). A shaded module will activate the bypass diode and its frequent activation may lead to its damage. SolarEdge monitoring will detect faults and protect the module chain from performance degradation.
The SolarEdge warranty covers the inverter for 12 years and power optimizers for 25 years. These periods begin 4 months from the date SolarEdge ships the products or when the products are installed, whichever occurs first.
The warranty is limited because its application may be waived in certain cases, e.g.
If the product (e.g. inverter or optimizer) has been damaged due to misuse, abuse, accident, neglect or lack of maintenance. Excerpt regarding SolarEdge warranty exclusions
However, the installation manual does not contain any maintenance information. Older inverters with an LCD display and an external fan required annual fan maintenance by removing accumulated dust.
However, currently produced inverters do not have this requirement. Nevertheless, it is worth checking from time to time whether dust has accumulated on the heat sink, which would impede the cooling of the inverter.
You can extend the inverter warranty to 20 or 25 years. This must be done within 24 months of shipment of the inverter from the SolarEdge factory. The prices are as follows:
|Solar Edge Product
|Warranty extension to 20 years
|Warranty extension to 25 years
|SolarEdge 1-phase HD-Wave 4-6 kW inverter
|SolarEdge 3-time inverter <15 kW
- Solar Edge is a system that offers optimization of yields from individual PV modules.
- The Solar Edge system shows the most benefits, especially on difficult, multi-faceted roofs
- The warranty for the inverter is 12 years and can be extended to 20 or 25 years.