Photovoltaic plants are steadily gaining popularity as an environmentally friendly means to generate power. One related question is how the vast outdoor installations can be protected against theft, unauthorized access and vandalism. Dallmeier has developed an intelligent and efficient surveillance concept which is already in use across a number of photovoltaic plants in the Czech Republic.

Photovoltaics mean the direct conversion of sunlight in electrical power through so-called solar cells. A heightened environmental awareness and financial assistance by the government for renewable energy projects have led to the construction of numerous photovoltaic plants. A reliable protection of the usually vast areas against theft or sabotage is not only in the interest of the operators. In the Czech Republic security systems are also demanded by insurance companies and investors. The requirements for video surveillance and analysis are clearly defined: The system is meant to reliably issue alarms if an unauthorized person should attempt to access the area. At the same time, false alarms triggered for example by weather effects or animals, should be reduced to a minimum.

Regensburg based CCTV/IP experts Dallmeier collaborated with local partner NSN CS in developing a high-performance video surveillance system for a photovoltaic plant in the South of the Czech Republic. An intelligent video analysis system, namely the DVS 1600, ensures a reliable perimeter protection and automatically displays the images to operators at a security room. However, the Dallmeier solution offers another decisive advantage. Through the use of thermal imaging cameras the power consumption of the surveillance system can be significantly reduced, which increases the efficiency factor of the photovoltaic plant.

Hynek Matocha, Technical Manager at NSN CS, explains: “The operators of the photovoltaic plant had informed themselves thoroughly about CCTV systems in solar plants. Usually, cameras with infrared lighting are used in order to get usable image material at night. However, particularly the high energy requirement of that concept and the rapid wear and tear of individual components pose a problem. Therefore, Dallmeier and NSN CS developed a new, more efficient and more reliable surveillance concept.”

Thermal imaging cameras with low power consumption
Compared to other current concepts, the new system uses thermographic cameras instead of cameras with additional infrared light. The smart idea was devised by Abbas, Dallmeier’s local distributor in the Czech Republic. The FLIR cameras produce high-quality thermal images during daylight as well as in complete darkness. In contrast to other night vision systems, which require residual light to produce images, the FLIR cameras do not need any light at all. Thus, an additional infrared lighting is no longer necessary. Since no additional lighting is used the operating costs of the video system are significantly lower, which means that, despite the higher acquisition costs of the thermal imaging cameras, the investment quickly pays off.

Reliable analysis with the DVS 1600
The camera images are recorded on a Dallmeier DVS 1600. Apart from the recording the DVS 1600 also offers intelligent video analysis. The Czech photovoltaic plant uses the “Intruder" analysis in order to immediately detect unauthorised access. Hynek Matocha explains the reasons: "The plants are often installed in remote areas where thieves can go unnoticed while dismounting entire modules. Usually the thieves break through the fence or the entrance gates using trucks to gain access. Unfortunately sabotage is a problem, too. Some people attempt to climb over the fence and then wilfully damage the valuable installation.”

Matocha is more than happy with the results of the Dallmeier video system." The system reliably triggers alarms in case unauthorised persons attempt to access the premises. At the same time, the number of false alarms is nominal", he says.

During the video analysis the DVS 1600 detects the movements in a given video sequence. The moving objects can be persons and vehicles but also branches, grass, animals or shadows. In order to minimise the number of false alarms the detected objects are subjected to a comprehensive validity check. Decisive criteria for the check are for instance the size and the direction of movement of an object.

If an object fits the alarm grid, two important steps are initiated. In a first step the alarm triggers the recording at the DVS 1600. The video server stores a parameterisable time period prior to and after the alarm and associates the alarm with the alarm image. The alarm is saved in a database and can be investigated at any time. The second step is automatically forwarding the alarm to the security centre where the alarms can quickly be verified and further action be initiated, if necessary. "We are currently considering the possibility to address intruders via speakers from the security centre in order to limit the damage”; Matocha says. ”That is another interesting option that Dallmeier proposed to us."

Easy configuration
Hynek Matocha is particularly excited about the easy operation of the DVS 1600: "People always think that installing and configuring a sophisticated video analysis system is a highly complicated job. That is totally different with the new DVS 1600. It is easy to see that Dallmeier have put special emphasis on an intuitive user concept.” A wizard was developed that guides the user step by step through the individual steps of the configuration. “All steps are easily understandable and are also explained in an online help. So the configuration is really simple. The wizard also makes sure that no important steps are forgotten", says Matocha.

Image transmission with PRemote
Photovoltaic plants are often built in remote areas where high-bandwidth networks are usually not available. Nevertheless it must be ensured that the images of the video system are transmitted to the security centre reliably and in good quality. For those kinds of requirements Dallmeier has developed a special transmission method called PRemote. The particular codec is optimised for low bandwidths, enabling fast image transmission even at low bit rates.

In contrast to other low-bandwidth transmission techniques such as Dual Streaming, PRemote allows not only the transmission of live images but also of recorded footage. A multisplit is also easily possible. Roman Pernica from OP Security, the man responsible for the technical operations at the security centre, explains: "The high performance of PRemote is simply convincing. One decisive advantage is the short transmission delays for the control signals of the Pan/Tilt/Zoom cameras. Hence, PTZ cameras can also be controlled manually via networks with low bandwidths.

Further installations planned
The surveillance concept by Dallmeier has proven itself in practice so well that further projects are already planned. Hynek Matocha explains: “The operator of the photovoltaic plant is highly satisfied with the new surveillance system. We are already in the process of equipping other plants with Dallmeier technology.”