STATE 518
Internal DSP malfunction
A malfunction was detected in the digital signal processor (DSP), which manages critical real-time control functions within the inverter.
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Expected Behaviors
- The inverter is displaying a STATE 518 message indicating a warning. It typically continues operating, but other errors may also be present. Press ENTER on the inverter to acknowledge the message and check the menu for additional status codes.
State Class
A state class is a generalized description of errors, catagorized by the number the STATE code starts with.
These messages typically do not stop the inverter from feeding energy into the grid. They are usually informational, such as logging problems, low-priority hardware faults, or maintenance notices. The inverter continues operating normally, though performance may be limited in some cases. Users can acknowledge the message by pressing the ENTER button. If the warning persists or if there are other symptoms, the system should be checked by a qualified technician.
- In some cases, power cycling the inverter may clear the 518 error state. To do so, disconnect both the DC (solar) and AC (grid) power sources, both must be turned off to allow the inverter to discharge. Leave the system off for approximately 3 minutes, then restore AC and DC power. Once back on, the inverter will conduct a series of self-tests, then enter a startup process that will take about 5 minutes (required by code). After which, the inverter should return to normal operation.
- If this issue persists, it may be that the inverter has detected a fault within the external wiring and components, or an internal failure in the inverter. Further diagnosis, such as live circuit testing and internal inspection is required to troubleshoot further, which should only be performed by a trained Fronius Service Provider. Defective components or the inverter itself may require replacement.
Tips for Qualified Persons
The following procedures involve safety risks and potential for equipment damage. They are intended only for qualified personnel trained to identify and avoid the hazards that exist, and possess the appropriate PPE. These are general tips to aid professionals in troubleshooting, not instructions or directives to perform them.
We assume no liability for injury or damage resulting from their use.
- Perform a hard power cycle by disconnecting both the DC and AC power sources allowing sufficient time for internal capacitors to fully discharge, then reconnecting both power sources to restart the inverter.
- If all inspections and diagnostics have been completed and no resolution is found, it may be necessary to replace the faulty component, or the inverter itself. For advanced troubleshooting specific to your site, or to initiate a warranty claim, contact Fronius Technical Support at 1-877-Fro-nius (1-877-376-6487).
Fronius inverters in the U.S. typically come with a standard 10-year warranty. Starting in 2024, registering the inverter on the Fronius Solar.web website (the Fronius solar monitoring platform), extended the warranty by an additional 2 years, totaling 12 years of coverage, and updates the warranty start date to the actual installation date. Fronius has also offered warranty extensions of up to 20 years.
The inverter label, typically located on the bottom of the unit, lists the device serial number. To check if your inverter is still covered, call Fronius Technical Support at 1-877-Fro-nius (1-877-376-6487)
Founded in 1945 by Günter Fronius in Pettenbach, Austria, Fronius began as a repair shop for radios and electrical equipment. Recognizing the need for efficient battery charging, Günter developed a device to recharge car batteries, marking the company's first foray into energy solutions.
In the 1950s, Fronius expanded into welding technology, introducing the first welding transformer with magnet-yoke control in 1950. This innovation allowed for continuous adjustment of welding current, setting the stage for future advancements in welding systems. The company's commitment to innovation led to the development of the Transarc 500 in 1981, the world's first primary transistor-based inverter welding system, which significantly reduced power consumption. Fronius has since expanded into advanced welding automation recognized among key players in the industry, alongside firms like ABB, and Yaskawa Electric Corporation. Their current offerings include robotic welding systems, collaborative robots (cobots), and intelligent software solutions like Fronius Pathfinder, which provides functions for creating and simulating welding sequences. In 1992, Fronius ventured into photovoltaics, releasing its first photovoltaic inverter, the Fronius Sunrise, in 1995. This move marked the beginning of Fronius's Solar Energy division, which has since become a cornerstone of the company. Subsequent innovations include the IG inverter series in 2001, the SnapINverter technology in 2014, and the GEN24 Plus hybrid inverter in 2020, reflecting Fronius's ongoing commitment to advancing solar technology. Today, Fronius stands as one of the top-tier inverter manufacturers globally, often ranked alongside SMA (Germany), in terms of quality and market presence. While companies like Enphase dominate the U.S. microinverter space and SolarEdge leads in optimizer-based MLPE systems, Fronius remains a leading choice for high-efficiency string inverter systems, particularly in Europe, Australia, and commercial U.S. installations. Their inverters have robust build quality, excellent thermal performance (with active cooling), long warranties, and strong service support. With over 3.4 million inverters installed and more than 35 TWh of clean energy produced, Fronius competes head-to-head with larger players, maintaining a presence in premium residential and commercial markets globally.The best point of contact is your original installer
If the orginal installer is no longer available, contact a local Fronius Service Provider in your area.
Fronius Technical Support can also be reached at 1-877-Fro-nius (1-877-376-6487)
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