Teris Control: Industrial Internet of Things for the control of photovoltaic plants

The Teris Control project, just completed by Chirale for the client Teris Energia, brings together all the features of the 4.0 Transition — a digital-innovation process increasingly affecting small and medium-sized companies in our region, also thanks to the many support measures funded by both the PNRR and the regular programming of European funds.

In this case too, the project’s launch was made possible by public funding — specifically by the Voucher for Digital Innovation call published by the Rome Chamber of Commerce.

The main elements that characterise Teris Control could not be more topical: renewable energy, digital process automation, Industrial Internet of Things and Machine Learning — in practice a textbook “use case” worth telling.

But let’s proceed in order, starting from the Client and its needs.

Teris Energia is a leading company in consulting, design and installation of photovoltaic plants, in the residential, agricultural and industrial sectors.

Teris is able to assess the energy efficiency of buildings and industrial facilities and to propose improvement solutions based on the use of photovoltaic panels.

For several years, in addition to the design and construction of energy-production plants, Teris has also been offering its clients tools and services to monitor installations and check that the plant’s efficiency is maintained.

The software platform that makes this service possible is called Teris Control, and the first version was built some years ago using technological solutions that were beginning to show their limits.

The project entrusted to Chirale made it possible to build a new version of the Teris Control system, in line with the most recent paradigms of the Industrial Internet of Things (IIoT) sector.

IIoT is the industrial evolution of the classic Internet of Things (IoT) model, usually used in domestic or personal applications involving more or less “smart” devices connected to the Internet.

In the industrial domain, the devices connected to the Internet are control systems for production processes or single plants.

In our specific case, the systems to be controlled are photovoltaic plants — made up of panels, energy-storage batteries and the many devices that control the process and measure its efficiency.

Examples of devices used in photovoltaic plants are the battery charge controllers, the inverters that convert the DC voltage from batteries into the AC voltage of the domestic (e.g. 220 V) or industrial (e.g. 380 V three-phase) standard, and the multimeters that measure available and supplied voltages, currents and powers.

Most industrial-class devices can communicate with electronic control systems via the ModBus protocol, usually implemented over an RS485 serial link.

This is a fairly old protocol — the first standard dates back to 1979 — but widely used and well known to anyone working in automation and home/building automation.

In traditional control applications, the devices are governed via microcontroller systems (PLCs – Programmable Logic Controllers) or via dedicated personal computers.

With the advent of the Internet, many systems were made network-accessible and remote-monitoring and -control applications were developed.

The first version of Teris Control belonged to this type of architecture.

The new system designed and built by Chirale, on the contrary, uses a more flexible and especially more scalable architecture, based on an IIoT model.

The data on the parameters provided by the various devices are read periodically by dedicated control devices based on industrial-class microcontroller development boards — model Arduino PRO MKR WAN 1013 — equipped with an RS485 serial interface.

Through the ModBus-over-RS485 protocol, data is acquired from the devices and forwarded to the central monitoring-and-control system, reachable via a dedicated HTTP URL in line with the REST API paradigm.

The Central System is a Cloud Computing application usable by Teris Energia’s technical staff and by Clients who have signed a dedicated contract.

The distinctive features that make the system innovative, flexible and scalable lie in the architecture used for the connection to the Internet.

By definition, in IIoT or IoT applications it is necessary to implement the link between the smart object or device and the Internet.

The immediate, apparently most obvious solutions that come to mind are leveraging a wired LAN (Ethernet) or Wi-Fi network providing routing to the Internet — if the device is inside a home, an office or a factory — or using GPRS or LTE cellular connectivity if the device is in open spaces not covered by Wi-Fi networks.

This kind of solution, however, in cases like this one has many drawbacks.

First, these are broadband connections — capable of transmitting millions of bits per second — and therefore usually expensive and energy-hungry.

A system like Teris Control, on the contrary, needs to acquire some hundreds of bits per hour — if not per day — so a Wi-Fi or even GPRS bandwidth would be used for only a few millionths of its capacity!

Moreover, the system configuration would depend on the customer’s home or company network — an entity that is usually not under Teris’ control, especially after the installation works are completed.

The problem of the uselessness and cost of broadband for IoT systems is well known, and in recent years it has driven the development of protocols called LPWAN — Low Power Wide Area Network.

These are standards based on radio-frequency connectivity, able to connect — with a very limited bandwidth but high quality and reliability — hundreds of remote devices to a few gateways, which in turn have broadband Internet access.

Among all the offerings on the market, our choice fell on the LoRaWAN protocol, which seems to be the one currently spreading the most.

Among the many advantages LoRaWAN offers is the possibility of building one’s own network infrastructure and installing gateway devices without having to apply for licences or hold concessions.

The frequency band used in Europe by the LoRa radio protocol on which LoRaWAN is based is the one at 868 MHz, which — within the limits set by law — is free and usable by anyone.

In the Teris Control project, Chirale designed and built a private network infrastructure that allows Teris to extend coverage over time for its data-connectivity needs, as new customers are acquired and new plants built.

The costs of building and maintaining the LoRaWAN network of Teris Control are very low and, above all, follow a perfectly scalable model.

The Arduino MKR WAN 1013 microcontroller boards natively provide LoRA connectivity.

The last distinctive element of the new system is the collection and use of the monitoring data to train a neural network capable of autonomously recognising alarm situations or situations needing attention, implementing at the same time a predictive-maintenance system.

At the moment, machine-learning technologies are used at the central-system level, since the main training phase is not yet completed.

Later, the pre-trained neural networks will be installed on more powerful microcontroller devices — such as the Arduino Portenta H7 — to implement an Edge Computing / Tiny Machine Learning paradigm.