Photovoltaics present an innovative alternative to traditional power sources in enhancing safety and control through remote monitoring systems and their vital applications in security and defence.
Is it possible that the tiny electronic devices, made of just several micrometre-thick semiconductor layers, can protect anybody or anything? Yes, but in a completely unconventional way. By the delivery of electric energy in a quiet, undetectable, sustainable way in a place where no other source is able to do this. Today, I invite you to the world of very special applications, where photovoltaics is an unspoken hero on guard of our daily safety.
Remote monitoring enhances safety and control
We can observe that, recently, the remote monitoring digital systems are becoming more and more popular in the private real estate sector, commercial buildings, on the roads, at airports, and in border supervision. Owing to the rapid development of electronic cameras and sensor systems, we can control an impressive number of parameters. Starting from simple motion detectors, through speed measurement by RADAR and LIDAR (Light Detection and Ranging) systems, until very sophisticated infra-red passive and active detection of people, animals and surrounding objects. Using high-resolution digital cameras connected to a security network may be highly effective by transferring records over an internet protocol (IP) network to a PC server with special artificial intelligence (AI) video management software installed. There, the fast analysis of the situation may be automatically employed, potential threats detected, and suspects identified by their face recognition or registration number identification. Alternatively, the smoke detectors or heat sensors can prevent wildfires in rural areas or in highly urbanised districts. Carbon monoxide sensors are still on alert in many houses using burning fire, while afterdamp detectors are saving human lives in mines and refineries.
Overcoming challenges in the field: The potential for photovoltaics
The specifics of all those systems are a wide dissipation in the monitored area, often far from the energy supply lines and the need for remote control and wireless communication. Very often these kinds of installations are located in the field as temporary objects (e.g. during the building/road construction processes) and should be active constantly within the designed period of time. Moreover, by the specifics of work, in many cases, these systems should be invulnerable to the power delivery outage by traditional cables, whether caused by natural accidents or deliberate intruder actions. Additionally, we should keep in mind that the costs of transformers and cabling needed for the delivery system in the rural area may, in many cases, greatly surpass the price of the sensors or miniaturised cameras.
On the other hand, the electronics used for the operation of all those cameras and sensors are supplied regularly by low-voltage DC (Direct Current). Considering this, the modern battery solutions seem necessary for a sustainable power supply. Nevertheless, even the highly-efficient lithium-ion (Li-Ion) batteries are vulnerable to the environmental conditions, heavy, cumbersome and foremost time-limited as a source of energy. Thus, photovoltaics is coming into the fray. Low-cost, small dimension and possibly flexible photovoltaic cells, integrated with the charge controller and miniaturised battery system, create a great opportunity for surveillance systems. Currently, we may observe the initial stage of these devices, equipped with the first generation of monocrystalline silicon micro-modules. They are relatively effective; however, their level of integration, durability and work requirements still need to be optimised.
Applications in defence
Another important field of application is connected with modern warfare equipment. In almost every aspect of the modern combat field, the use of electronics and electric equipment is absolutely crucial. Starting from telecommunication, enemy detection and weapon guiding systems, to drone charging and control, electric energy delivery is the backbone of every military force.
Traditional liquid-fuel power generators, widely used all around the world, are absolutely disastrous in this role. Not only are they heavy and must be constantly equipped with hectoliters of gasoline, but they are noisy, and as the by-product of the operation, they generate more heat than electric power. This, of course, makes them perfect targets for the enemy missile guidance systems.
Advancing PV for new applications
For these applications, thin-film flexible PV modules may be much more effective. For example, thin film, lightweight, rollable and portable PV modules may deliver electricity for a long period of time in extensive combat missions. Currently, experiments aimed at the reduction of their visibility in the optical and radar spectrum alike are underway. Irregular module shaping and effective antireflective coatings are the possible solutions. These kinds of devices may also be easily incorporated into the structure of backpacks or tents, with prototype peak power reaching up to 1 kW.
For all of these applications, a cheap, efficient and stable thin film PV structure is needed. One of the potential candidates for this kind of material is the Sb2S3 semiconductor compound, which is currently being investigated in the Laboratory for Thin Film Energy Materials at TalTech. This semiconductor may be deposited by an inexpensive and effective spray pyrolysis technique, with the potential conversion effectiveness higher than traditional silicon. This production technology and material structure make it possible to achieve a higher integration level with the elements of various shapes and dimensions. Semi-transparency of these layers gives an even chance for deposition on windows, visors, binocular lenses, and other optical equipment. Let’s see what the future of security systems will be when equipped with robust and stable PV energy sources in the near future.
Acknowledgement
The work was supported by EU Horizon 2020 project 952509-5GSOLAR
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