Modernising Remote Monitoring: Internet Connectivity and Cloud for Existing Turbines

Monday morning in the operations office: one turbine has not reported in since Saturday. The modem at the tower base still dials, but the connection drops after a few seconds because the telephone line has long since been switched to IP technology. So someone drives out, reads the fault off the terminal, acknowledges it by hand and jots the values down on a slip of paper. Two days of downtime for a message that could have been dealt with remotely in minutes.

Many operators of older wind turbines are familiar with situations like this. The turbines themselves often still run reliably, but the technology around them comes from another era: dial-up modems, ISDN cards, GSM modules, isolated terminals or manufacturer portals whose support is coming to an end. This technology does not fail all at once; it becomes less reliable bit by bit.

In this article we show what modernising a remote monitoring system actually involves, which options are available and what you should look out for in terms of IT security, manufacturer lock-in and data sovereignty. We are an engineering office based in Warburg, we develop manufacturer-independent remote monitoring systems and we have been operating our own wind turbines since 1998. What we describe here is the path we take together with operators.

Why legacy remote monitoring is becoming a risk

A remote monitoring system has two jobs: it reports faults quickly, and it supplies the operating data you use to demonstrate yield and availability. If the data path fails, you usually only notice when a period of downtime lasts longer than necessary. With older turbines, three developments come together that threaten this data path.

Modems, ISDN and the switch to All-IP

Many turbines from the 1990s and early 2000s, such as the Vestas V47 or V66, Enercon E-40 or E-66, Südwind S46, DeWind D4/D6 or Tacke and AN Bonus machines, were originally polled via telephone modem or ISDN. The major telecommunications network operators in Germany have now largely switched their lines to All-IP. All-IP means that telephony, too, runs as a data stream over the Internet Protocol.

For a telephone call, that is not a problem. A modem, however, transmits its data as tones, and these tones are digitised, compressed and split into packets along the way. The result is dropped connections, very slow transmission or no connection at all. An adapter on the router can sometimes bridge the gap, but it is not a reliable long-term solution.

Mobile networks: the end of 2G has been announced

Where there was no landline at the tower base, GSM modems were often used. The 3G network has already been shut down, and Telekom has announced that it expects to switch off its 2G network completely on 30 June 2028. It expressly advises replacing old radio modules in machines in good time, because early planning reduces costs.

For you, this means that a modem that still communicates via 2G today has a foreseeable expiry date. If you plan now, you can combine the replacement with a genuine modernisation instead of merely swapping the radio module shortly before the shutdown.

Manufacturer portals, spare parts and know-how

On top of this come systems that are tied to a manufacturer or a former service provider. Once their support ends, there are no more updates, spare parts become scarce, and often only one person still knows the password for the terminal. At that point, at the latest, the monitoring of a running turbine depends on a single computer or a single person.

What modernisation actually means

Modernising does not mean rebuilding the turbine. In most cases it is about the data path: how the values get out of the controller, where they are stored and who is allowed to see them from where. The turbine controller stays in place, provided it supplies the necessary data.

The data path from the controller to the screen

A modern remote monitoring system consists of a few clearly separated building blocks. Each of them can be checked individually and replaced if necessary:

1. Interface to the controller: Older controllers often have a serial interface (RS-232 or RS-485) to which the modem used to be connected. A gateway translates this data into a network protocol.
2. Recording: A database server stores power output, wind, operating states and messages continuously and fully automatically.
3. Transmission: Routers using mobile networks (4G/5G), DSL or fibre-optic cable (LWL, glass fibre) connect the site to the internet.
4. Access: Via an encrypted connection or a cloud platform, you can view data and messages in the office, on the move or on a live display.

The term SCADA often comes up in this context. It refers to a system for monitoring and controlling technical installations (Supervisory Control and Data Acquisition): it collects measured values, displays states and passes commands on to the controller. At its core, a remote monitoring system is a small SCADA system for your turbines.

What stays and what is replaced

What stays is decided by the site survey. Typically, modems, old terminals and software that is no longer maintained are replaced. The turbine controller, existing cabling within the wind farm and functioning sensors stay in place if they meet the requirements.

How the old data is handled is important. If a terminal or a legacy computer holds years of operating data, this should be backed up before the conversion. Whether it can be transferred to the new database depends on the format and is part of the technical clarification.

Router with VPN, on-site server or cloud: the options compared

There is no single right solution. Which option suits you depends on how many turbines you operate, who needs access to the data and how important a complete data history is to you. The three basic options can also be combined.

Option 1: router with VPN

The simplest level replaces the modem with an industrial router. Access runs via a VPN (Virtual Private Network), i.e. an encrypted tunnel through the internet that is open only to authorised devices. This lets you see the turbine's user interface as if you were sitting at the tower base.

This solves the problem of reachability, but not that of data storage. Without your own recording, you only see what the controller itself stores. For single turbines with little need for analysis, that may be sufficient.

Option 2: on-site database server

Here, a database server on site continuously records all values. The data is therefore physically with you, independent of an internet connection. A live display shows the current status in the office or on site, and you access the system remotely via a secure connection.

This option is particularly suitable if you want to keep your data in your own hands or if the connection at the site is not always stable. You can read more about this in our article on online monitoring with a database server and live display.

Option 3: connection to the cloud

With a cloud connection, the site transmits its data to a server in a data centre. You and all authorised persons, such as the technical operations manager, service company or co-shareholders, access it via a browser. Several sites appear in a shared view.

Technically, open protocols can be used for this. MQTT is a lightweight protocol in which devices send measured values to a central broker, and it is well suited to fluctuating mobile connections. OPC UA is an industrial standard for manufacturer-independent data exchange between machines and software. What matters is less the protocol than whether you can get all of your data out at any time.

The line to the site: DSL, mobile network or fibre

Each of the three options needs a connection from the site to the internet. Which technology fits depends on the location, the volume of data and the required reliability. Video surveillance needs considerably more bandwidth than the transmission of operating data alone.

Mobile networks with 4G and 5G

For many single turbines, a mobile connection is the obvious solution because no cable needs to be laid. The decision should be preceded by a signal measurement at the tower base, not just a glance at the coverage map. External antennas on the tower often improve reception considerably.

Mobile solutions frequently use a private APN (Access Point Name). This is the access point through which the mobile network routes the data directly into a closed corporate network instead of the open internet. We explain why a private APN alone is not enough in the section on IT security.

Fibre-optic cable in the wind farm

In wind farms, a dedicated fibre-optic data network often pays off. The turbines are connected to one another, and only one point in the wind farm needs the connection to the outside world. This reduces the number of mobile contracts and creates a stable basis for cameras, shutdown systems and direct marketing (Direktvermarktung). You will find details on planning and selection in our article on 4G/5G mobile networks and fibre.

IT security: internet connectivity without open doors

Connecting a turbine to the internet fundamentally makes it vulnerable to attack. This is not a theoretical risk. In October 2026, the German Federal Office for Information Security (BSI) published the recommendation BSI-CS 154 "Gefährdung durch internet-verbundene OT-Systeme" ("Threats posed by internet-connected OT systems"). It is expressly aimed at operators of small power generation installations as well, including wind turbines.

In it, the BSI describes coordinated attacks on wind farms in Poland in December 2025. The attackers exploited unchanged factory login credentials, reused passwords and a mobile network connection in which devices belonging to different installations could communicate with one another unhindered. The vulnerabilities were simple; the consequences were disrupted controllers and interrupted communication with the grid operator.

No direct access from the internet

The BSI's most important rule is that controllers, visualisations and the administration interfaces of routers must not be directly reachable from the internet. Port forwarding to turbine devices should be switched off. For any necessary remote access, a VPN is the minimum requirement.

In concrete terms, for a modern remote monitoring system this means: the connection is established from the site, and no service is exposed to the outside. Passwords are individual to each device, factory accounts are deactivated and, where possible, a second factor protects access. A dynamic IP address is expressly not a form of protection.

A private APN alone is not enough

According to the BSI, transmission within private APNs is often unencrypted, and without additional measures attackers can move between separate installations. A private APN therefore replaces neither encryption nor proper network segmentation. Firewall rules should permit only the connections that are actually needed; everything else stays blocked.

Know and document every access point

The BSI points out that remote maintenance access points are often not fully documented and that some operators are not even aware of them. An LTE modem left in the control cabinet by a former service provider is a typical example. In a modernisation, every existing access point should therefore be scrutinised: keep it, secure it or remove it.

Manufacturer lock-in and data sovereignty

Older remote monitoring systems show what happens when a system is tied to a single supplier: when that supplier's support ends, access to your own data often ends with it. In a modernisation, you should therefore look not only at features but also at dependencies.

Open interfaces instead of isolated solutions

We work on a manufacturer-independent basis. For you, this means that the remote monitoring works with turbines from different manufacturers, and several makes can be combined in one system. Open protocols such as MQTT or OPC UA and documented data formats ensure that other programs can process the data as well.

Your data belongs to you

Before you start, clarify where the data will be stored, who has access and how you can obtain a complete export. With an on-site database server, the data is physically located in your installation. With a cloud solution, it should be agreed in writing that you can get your data out at any time and in a common format.

Also check whether a permanent cloud connection is really necessary for operation. The BSI recommends reviewing connections to manufacturer services to determine whether they are necessary. A solution in which the turbine continues to run and record properly without the cloud is more robust than one that goes blind without the internet.

Grid operators, direct marketers and shutdown systems

Remote monitoring is rarely the only data connection a turbine has. Grid operators, direct marketers and permit conditions each impose their own requirements. A modernisation is the right moment to look at these connections together.

Remote controllability under the EEG

Under Section 9 of the German Renewable Energy Sources Act (EEG), operators of installations of 100 kW or more must provide equipment that allows the grid operator to retrieve the actual feed-in and to reduce output by remote control. For direct marketing, Section 10b EEG imposes a corresponding requirement in relation to the direct marketer. There, the law requires communication technology that reflects the state of the art and refers to the standards and recommendations of the BSI.

We connect wind farms and single turbines to direct marketing via EMSYS, including the data interface to the direct marketer and the implementation of schedules and curtailments at the turbine. You can read more about this in our article on connecting to direct marketing via EMSYS.

Bird, ice, bat and sector-based shutdown

Many permits require shutdowns: when ice forms, to protect birds and bats, or in certain wind direction sectors. These systems supply signals to which the turbine must respond automatically. We integrate them into the controller and make their interventions visible in the remote monitoring system.

This has a practical benefit: when a turbine is at a standstill, you can see immediately whether there is a fault or a mandatory shutdown is in effect. Cameras and remote switching can also be used via the same connection, so that you can start, stop and control turbines remotely.

What modernisation costs and what it delivers

We deliberately do not quote flat-rate prices, because the range between replacing a router on a single turbine and reconnecting a mixed wind farm is wide. The effort can only be estimated reliably after the technical clarification. What we can tell you is which factors determine it.

What the effort depends on

• Number and type of turbines: Identical turbines in a wind farm can be connected in a uniform way; mixed fleets need more adaptation.
• Controller interfaces: If the controller supplies its data via a documented interface, connecting it is simpler than with proprietary protocols.
• Line to the site: A mobile connection with good reception is set up quickly; a new fibre-optic route within the wind farm means civil engineering work.
• Scope: Pure data transmission, database server, live display with remote control, camera and external systems build on one another.
• Customer-side prerequisites: Supply cables, telephone connections and the power supply are provided by the operator, and this affects the installation effort.

What you get in return

The most tangible benefits are trips avoided and shorter periods of downtime. If you can read and assess a message remotely, you can decide more quickly whether someone needs to go out and with which spare part. With remote switching, some faults can even be resolved without a site visit.

In addition, you get a complete data history. It demonstrates availability to insurers, service companies or banks and helps you decide whether continued operation is worthwhile. And last but not least, a risk disappears that cannot be expressed in euros: the risk that one day the monitoring simply stops working.

How a modernisation project works

With us, a modernisation project follows a fixed sequence. It starts with the question of what is already in place at the site. Only then are planning, manufacturing and installation carried out.

Step zero: the site survey

Before we submit a quotation, we clarify the technical framework together with you. The following overview shows which points we check and why they matter. You can gather many of them in advance.

From order confirmation to handover

1. Order confirmation and technical clarification: After this, we set the expected delivery date. Our quotations remain valid for three months.
2. Design and manufacturing: We build the system to the agreed scope of delivery, for example control cabinet, server, router and gateway.
3. Readiness for dispatch and transport: Once readiness for dispatch has been notified, the equipment is shipped to the site.
4. Installation and commissioning: Mechanical and electrical installation and commissioning take place on site. For this, we bring in professional service companies.
5. Handover, instruction, documentation: We instruct you during the commissioning phase and hand over the documentation. Final acceptance takes place no later than two weeks after the start of commercial operation.

After the handover

A remote monitoring system is not a project that ends with the handover. Routers and servers need updates, passwords and access rights must be maintained, and the BSI recommends making security checks a routine. Remote administration of the system is handled by our office during normal business hours; we offer maintenance and spare parts as required.

Frequently asked questions

Conclusion

The remote monitoring of older wind turbines often relies on technology whose end is in sight: modems on IP lines, GSM modules facing the 2G shutdown, portals without support. A modernisation renews the data path without rebuilding the turbine. Whether you choose a router with VPN, an on-site database server or the cloud depends on your turbines, your users and your requirements for the data history.

If you plan now, you can build in security, manufacturer independence and data sovereignty from the outset, instead of merely swapping a module under time pressure. The first step is an honest site survey. If you would like support with this, please get in touch.