Monitoring and remote management of photovoltaic systems is a strong growth sector in our country and which faces critical issues connected, not only to large dimensions – a system has a significant quantity of data which must be monitored, with specific problems which are different from those of other types of energy production plants – but also to the protection of considerable investments which allow them to be installed.

Roberto Caspani, a systems integrator in the province of Bergamo who has worked in the remote management and tele-measurement sector for fifteen years, has created a monitoring system for 20 photovoltaic plants in cooperation with EFA Automazione using the products offered by the Belgian company eWON, and inserting them in the Energ&metrY integrated solution (www.energemetry.net).

Medium voltage monitored by remote management

“The problems with a medium to large photovoltaic system are related, first and foremost, to the connection to the medium-voltage line, which could be subject to voltage or frequency variations” the engineer stated. “The management offered by the monitoring system, in this case, must promptly report these variations so that action can be taken immediately over the Internet, even with just a Smartphone or a tablet”.
Caspani explains how the monitoring and the alarms which signal deviation of the medium voltage are fundamental within a photovoltaic system, because they let maintenance personnel know in a very short time - in this case about ten seconds - which system has a fault, which area it is in and with which parameters, so that they can take action to solve the problem.

The operation can take place in one of two ways: entirely remotely or on site. The operator connects to the Internet with any fixed or mobile device and from the digital Energ&metrY platform is able to establish whether to take action remotely or to go send technical personnel on site to activate switching or conduct the appropriate checks. This is possible thanks to the remote management feature implemented in the eWON devices which provides a web-based interface that displays all the monitored system parameters. “Naturally, in the event of remote action” added Caspani “a careful analysis of possible consequences is required, connected to the fact that at the time of the operation and due to delays on the IP network, the means line has incorrect parameters, therefore the result may not be effective or it may even damage the inverter”.

Considering the high commercial value of these systems – which is around three million euros – only expert maintenance personnel can decide what action to take.
In summary: eWON provides an interface with the inverter, weather station, medium-voltage protection interface, electrical production meter for GSE charging, medium-voltage transformer temperature, etc. These components are all subject to heavy electrical and environmental stress which determines their reliability.

eWON, the simple and powerful solution

“In this first phase of development of the system, tested on 20 Megawatts - which corresponds to twenty 1 Megawatt systems – I was able to see how a product which comes out of the traditional industrial automation sector can be so perfectly adaptable to a new and highly differentiated environment such as photovoltaic energy, even foreseeing the use of other sources of renewable energy such as wind farms, biomass, and hydroelectric power”, said Caspani.

The fact that it is modular is important in the photovoltaic field because that allows costs to be optimised. This connectivity is guaranteed by the HSUPA band. In fact, the eWON device is equipped with a 7.2 Mb download and 5.76 Mb upload HSUPA communicator. This kind of connectivity eliminates the need for other solutions such as Wi-Fi or Wi-Max, which in any case may or may not cover the site concerned, and which have significantly higher costs if they are available.
Thanks to this band, streaming video can be used, both in real time and delayed, accessing the digital video recorder at the system site, whilst eWON acts as a gateway for all the technological components on site, including the security system.

“You must remember that there are a lot of people involved in a photovoltaic system” Caspani says. “First and foremost there is the end customer, who must be guaranteed plant productivity through the monitoring system reports. The second figure is the maintenance operator for the physical infrastructure with all of its components – panels, inverters, cabling, cables, panel cleaning, fencing. Then there is the security company that manages alarms which the plant generates: personnel who are notified immediately in case of burglary attempts and who arrange to have a patrol sent on site. Unfortunately this is an event which has occurred often recently, especially theft of panels or cables. The fourth and final player is the alarm system maintenance operator who checks and repairs sensors and video cameras”.
The sum of these figures revolves around the eWON device, which therefore becomes the core of the system and is used to its maximum potential.

A choice determined by the infinite possibilities of customisation

“I have been working in the machine to machine remote management sector for fifteen years and I was already familiar with eWON products, but after working on this project I was surprised by the multiple uses and features that it offers” said Caspani. “In larger corporate organisations work is usually done in a different way, striving to develop internal solutions: the application is built using hardware with a communicator or an easily programmable operating system which is readily available on the market. The advantage of eWON is that it provides a wide variety of built-in features, that it can be adapted to the user's needs and easily configured with a few lines of code: web servers which provide access to all the eWON parameters but above all variables monitored by the plant, customised screens, addition of your own logo. Exactly the same as if it were an application developed from scratch”.

As regards this, Caspani also explains how, thanks to the availability of most of the industrial protocols managed by eWON, it was also possible to develop a distributed SCADA which simultaneously interrogates all the eWON devices in the field and returns a real time situation report on all the systems. The simultaneous display of all the systems with a centralised database was developed in the Energ&metrY digital platform which provides, in addition to immediate accessibility, additional functions such as production reports, all the system databases, a periodic maintenance and post-processing log which guarantees plant performance analysis, heavily influenced by the ambient temperature and ageing in addition to irradiation.

Ease of programming, rapid configuration, reliability of the objects: eWON is the ideal solution for systems integration organisations because it allows an application to be developed in the least possible amount of time. The rapport established over the years with EFA Automazione was also quite satisfying for Caspani. “EFA technical support, whom we contacted in the beginning for a few configuration adjustments, always responded quickly and efficiently and eWON was never lacking even in the background in terms of technical support and SW upgrades”.