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Fronius International Fronius Eco 25.0-3-S

Fronius International Fronius Eco 25.0-3-S

25 kW Grid-tie Three-phase
Compare with closest alternative Datasheet PDF
Rated AC (kW)
25.00
Typical for its class
Euro eff. (%)
98.0
Typical · median 98.0%
MPPT
1
Weak · bottom 1%
Max DC (V)
1000
Typical · median 1000 V
Weight (kg)
35.7
Typical · median 35.0 kg
Warranty (yrs)
-
Not published

The Fronius Eco series are three-phase grid-tie inverters designed for large commercial and industrial installations, where rapid installation, operational resilience, and stable energy production are essential. The transformerless design combined with its highly sealed IP66 housing enables the equipment to be installed outdoors without additional environmental safeguards. In practice, features such as the SnapINverter service system and integrated string fuse holders allow frequent elimination of separate DC combiner boxes.

Fronius Eco features 1 MPPT-ideal for locations where solar panel strings have similar orientations and minimal, uneven shading occurs. Its high European efficiency translates to better real-world performance under varying loads and temperatures, not just in laboratory conditions.

Monitoring is handled via Fronius Solar.web-communication can occur via Wi-Fi or Ethernet, with views available in the app and web browser. This is not a hybrid inverter, so it is not designed for direct integration with energy storage systems. The series meets required safety and grid connection standards and can be covered by the manufacturer’s warranty (including extensions).

Ranking

227 inverters from 12 to 30 kW
Metric This inverter Median Position in class Rank in class
European efficiency 98.0% 98.0% Typical 77
MPPT trackers 1 2 Weak · bottom 1% 161
Max DC input voltage 1000 V 1000 V Typical 101
Weight per kW 1.4 1.6 Typical 93
Warranty - 5 yrs Not published -
Colour key Strong - top 25% Typical - middle 50% Weak - bottom 25%

Price offers

2 from shops we track
Shop Country Price Per kW Stock Offer updated Link to shop
www.frexolaire.com France 2 649.92 € incl. VAT 106 €/kW In stock 4h ago Visit shop
supermercadosolar.es Spain 3 287 € incl. VAT 131.48 €/kW In stock 4h ago Visit shop

Specifications

Open datasheet PDF
Rated AC power 25 kW Continuous output
Max apparent power 25.00 kVA
Phases Three-phase
Nominal AC voltage 400 V 3~NPE 380 V / 220 V or 3~NPE 400 V / 230 V (+20% / -30%)
Grid frequency 50 Hz Range 45–65 Hz
Power factor 0–1 ind./cap.
Harmonic distortion (THD) 3.0 %
Max DC input power 37.80 kW DC/AC ratio 1.51
Max DC voltage 1000 V Caps the string length
MPPT voltage range 580 to 850 V
Start-up voltage 650 V
MPPT trackers 1 6 strings each
Max short-circuit current per MPPT 80.0 A Must exceed the panel's Isc
European efficiency 98.0 % Weighted across part loads
Max efficiency 98.2 % Best single operating point
Dimensions 725 × 510 × 225 mm Height × width × depth
Weight 35.7 kg 1.4 kg per kW
Enclosure IP66
Cooling forced-air
Operating temperature -25 to 60 °C
Max humidity 100 %
Max altitude 2000 m
Interfaces Wi-FiEthernet
Protocols Fronius Solar.webModbus TCP (SunSpec)Fronius Solar API (JSON)Fronius Solar Net (RS422)Modbus RTU (SunSpec) (RS485)
Protection DC switch
Certifications ÖVE / ÖNORM E 8001-4-712DIN V VDE 0126-1-1/A1VDE AR N 4105IEC 62109-1IEC 62109-2IEC 62116IEC 61727AS 3100AS 4777-2AS 4777-3CER 06-190G98G99UNE 206007-1SI 4777CEI 0-16CEI 0-21

Pros and cons

5 positive · 3 caution
What owners get
IP66 + transformer-less design

The IP66 protection rating, combined with a non-transformer power supply, allows for direct installation outdoors - without the need for additional protective enclosures. This reduces BOS (Building Owner's System) costs and installation time in typical commercial projects.

Maximum efficiency: 98.2%

Model 25.0-3-S achieves a maximum efficiency of 98.2%, placing the Eco series among the leading string inverters in the 25-27 kW segment. High European efficiency translates into a real annual yield under variable solar irradiation, typical of the Central European climate.

Integrated DC string fuses

Integrated string combiner box features eliminate the need for separate DC string combiner boxes. This simplifies the installation design, reduces setup time, and lowers material costs in commercial installations with multiple strings.

SnapINverter - service and replacement

The SnapINverter mechanical system allows a single person to install and remove the device without specialized tools. In practice, this reduces service downtime, which is crucial in commercial installations where every hour of downtime results in lost production.

Dynamic Peak Manager - a global MPPT solution for shaded conditions

The Dynamic Peak Manager (DPM) algorithm regularly scans the entire PV system and identifies the global Maximum Power Point (GMPP), even in the presence of partial shading of the strings. It partially compensates for the limitations of a single MPPT tracker in systems with moderate shading.

Trade-offs
Only 1 MPPT - lack of orientation flexibility

The Eco series features a single tracking string with maximum power output (1 MPPT, 580-1000 V DC range). In comparison, the Fronius Symo Advanced in a similar power range offers 2 MPPT, which allows for the use of strings with different orientations or inclines without performance loss. The Eco is only optimal when the modules are in uniform, unshaded areas.

Narrow power range: only 25 and 27 kW

The series includes only two power options (25.0 kW and 27.0 kW). The absence of intermediate models (e.g., 20 kW, 22 kW) makes it difficult to precisely match the inverter to the project and may force the use of an oversized unit or multiple units, which increases installation costs.

The older SnapINverter platform lacks an active roadmap.

The Eco belongs to the SnapINverter generation, which Fronius is progressively replacing with newer lines (Tauro, GEN24 Plus). The Australian CEC certification expired on 01/06/2025, indicating a limited product lifespan. New firmware features and integrations (e.g., Vehicle-to-Grid, advanced energy management) are being developed exclusively for newer platforms.

Inverter Power Euro eff. MPPT Weight Difference
Fronius International Fronius Eco 25.0-3-S 25 kW 98.0% 1 35.7 kg You are here
MID 25KTL3-X2 (Pro.E) 25 kW 98.6% 3 24.0 kg +0.6 pp efficiency, +2 MPPT, 11.7 kg lighter
MID 25KTL3-X 25 kW 98.6% 2 23.0 kg +0.6 pp efficiency, +1 MPPT, 12.7 kg lighter
MID 25KTL3-X1 25 kW 98.5% - 29.5 kg +0.5 pp efficiency, 6.2 kg lighter
GW25K-MT 25 kW 98.4% - 40.0 kg +0.4 pp efficiency, 4.3 kg heavier
Fronius Verto 25.0 400 25 kW 98.3% 4 35.2 kg +0.3 pp efficiency, +3 MPPT
SG25T-P2-CN 25 kW 98.3% 2 19.0 kg +1 MPPT, 16.7 kg lighter
SUN2000-25KTL-M5 25 kW 98.2% 2 21.0 kg +1 MPPT, 14.7 kg lighter
SOFAR 25KTLX-G3 25 kW 98.2% - 36.0 kg Similar on paper

About the Fronius Eco series

6 answered

These answers cover the whole series. Where a figure differs, the specification above is this model's own.

Can the Fronius Eco inverter be mounted outdoors without the need for an additional enclosure?
Yes, the Fronius Eco features an IP66-rated enclosure, which means complete protection against dust and water jets. The inverter can be safely mounted directly on the exterior wall of the building without the need for additional enclosures or covers. This is particularly important in industrial and commercial installations, where space within the hall is limited.
Is a separate DC string box required for Fronius Eco installations?
In most cases, this is true. The Fronius Eco has integrated string fuses on both poles, meaning that the external DC collection box is often not required. This simplifies the installation, reduces material costs, and shortens the assembly time, which translates into significant savings in large commercial systems.
What are the MPPT capabilities of the Fronius Eco, and will it perform well in partially shaded conditions?
The Fronius Eco only has one MPPT tracker, so it works best in installations where all strings have the same or very similar orientation and tilt angle, without uneven shading. For complex roofs with multiple sections or partial shading (chimney, ventilation), a string inverter with two or more MPPT trackers is a better option.
What is the efficiency of the Fronius Eco inverter, and what does "European efficiency" mean?
The Fronius Eco achieves an efficiency exceeding 98%, and its high European efficiency (EU efficiency) takes into account realistic operating conditions: variable loads and temperatures typical of the Central European climate. This translates to higher energy yields throughout the year compared to devices advertised solely based on peak laboratory efficiency.
How does the monitoring function in the Fronius Eco inverter work, and is an additional gateway required?
Fronius Eco communicates wirelessly via WiFi or through Ethernet (LAN), eliminating the need to purchase a separate monitoring device. Production data and diagnostics are available on the Fronius Solar.web platform, accessible via both a web browser and a mobile app. The inverter also supports Modbus TCP SunSpec and Fronius Solar API, which simplifies integration with BMS and SCADA systems.
Is the Fronius Eco series still available for sale?
The Fronius Eco series has been discontinued and is no longer offered as a new product. If you are looking for a three-phase Fronius inverter for a new commercial installation, the current successor in the SnapINverter range is the Fronius Symo or newer models from the Fronius Primo/Symo Advanced family. Service and spare parts for existing Fronius Eco installations should still be available through authorized Fronius service partners.
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