BIPV is a promising new technology in the field of solar industry. More and more solar power plants around the world are used in close association with the architectural design, organically blended into the urban environment.
Building integrated solar power plants are mounted traditionally on flat and lean-to roofs and are integrated with frontages or elements of glazing: domes, glass roofs, floor-to-ceiling windows. BIPV solar power systems have a number of advantages over traditional photovoltaic stations:
To date, the most effective solution for the price/quality ratio among BIPV systems is glass/glass systems (modules) created on the basis of crystalline silicon modules. They combine the low cost of solar panels made using traditional technology and the aesthetically attractive look characteristic of thin-film flexible modules. They fully comply with the requirements of the European standard EN50583, which defines the requirements for BIPV modules as part of the building structure. For example, the glass/glass module is able to withstand a pressure of 8000 Ra – with such force, a layer of snow 8 meters high would press on the roof and have excellent sound insulation performance.
A big breakthrough in this area can be considered the entry into force of the new European standard – EN50583, which defines the parameters of BIPV. First of all, this standard gives a precise and unambiguous definition of BIPV – only those that will be considered as integrated photovoltaic panels must be replaced with other building materials or structures after removing them from the building in order to avoid violating the integrity of the building. This is precisely the key feature of the EN50583 standard – it gives clear definitions and defines the BIPV parameters, in fact they receive equal rights with traditional building materials.
According to the standard, building-integrated photovoltaic panels are these ones, which have to be replaced after their removal from the building by other construction materials or structures in order to preserve the structural integrity of this building. The standard defines clearly the functions that can be performed by solar power plants integrated with the building structure.
The standard also determines five methods of the installation of photovoltaic elements.
Up to now, the manufacturers of BIPV systems did not follow building standards during the production of solar modules. It is quite a paradox: the panels of BIPV systems are used in building instead of other construction materials. As a rule, they replace reinforced glass constructions. European standards regulate scrupulously the use of the vitrifaction, taking into considerations angles, thickness of the glass pane, frames and forms of glazing. However, there was never anything like this for BIPV systems. EN 50583 eliminates this defect, providing the same requirements to BIPV modules, relating to the way of their integration and the durability of the structure, as to the construction materials.
Solar modules, produced up to now, are not adapted in most of the cases for the use under atmospheric aggressive conditions: exposure to wind or snowfall. Glass/foil typical structures are protected by the layer of glass with the thickness of 3 or 4 mm, more modern double glass panels can meet the building standards only by chance. As usual, they are even not tested under aggressive atmospheric conditions. The standards IEC 61215 and 61730, regulating the production of these modules, are elaborated by the International Electro-technical Commission for BIPV crystalline-based modules, taking into consideration their electro-technical parameters (not structurally-mechanical ones).
Though IEC standards define the requirements to mechanical loads of solar modules, the experts of the commission do not detail this aspect. Thus, the explanation of the calculations of wind load value, according to the standard IEC 61730 takes about a half of a standard size sheet A4. For comparison, an analogous standard EN 1991-1-4, applied to building constructions in the European Union, comprises 250 pages. The standard EN 50583 transforms this approach.
Furthermore, the most important aspect of putting BIPV systems into operation, described by new standard, is the specialisation. The solar module integrated with the building frontage at the height of 5 meters shall bear much less axis load, weather effects and wind load than an analogous module mounted on the 50th floor. It is not profitable to use identical modules in the given situation. Thereby there is the necessity of the description of the requirements of various specialised modules. The standard spells out these requirements as the list of ways to fix the modules and the length of bearing surfaces defining the form and the type of module. The compliance with the standards calculated for glass structures helps to specify the parameters of the modules. In fact, the standard integrates photovoltaic panels with the existing operating models for glass frontages, domes and roofs, providing BIPV systems with the importance equal to other construction materials.
Designing BIPV systems is a very complex and time-consuming process, as a result it is necessary to find a compromise between the optimal conditions for the functioning of photovoltaic modules, the requirements of building codes, architectural component and economic feasibility. At the same time, standard solutions and software used for the calculation and design of standard solar power plants cannot be fully used here. In this case, it is very important to choose the right way to place BIPV elements and adapt the design of BIPV elements to the general architectural style of the building in order to obtain electrically and architecturally optimized systems. Designing BIPV systems is a job at the junction of several professions at once: architect, builder and electrical engineer.
Due to their design and mechanical properties, BIPV modules, beside their main function aiming for noiseless and environmentally sound power generation, are able to perform many other tasks, having replaced completely traditional construction materials. The degree of multifunctionality of photovoltaic module as a kind of construction materials is determined by its design and structure, which condition the aspects of technical, architectural and economic project development. The installation of BIPV modules allows replacing traditional construction materials. On the one hand, BIPV systems become cheaper than the construction materials instead of which the modules are installed. In addition, on the other hand, their use raises profitability of the investment. As a result, the installation of BIPV modules, in spite of initial outlay, can really be recouped faster than the installation of traditional photovoltaics. And, not to mention, BIPV systems are more attractive aesthetically, than standard roof solar power plants. They are able also to integrate in the buildings without affecting general architectural style.
One can define the next important particularities and advantages of BIPV systems, related to their multifunctionality:
As it was mentioned at the beginning of the article, about 99% of the solar power plant market are not subject to new standard. However, this rate can change in the nearest future. A lot of companies manufacturing solar energy units consider BIPV systems the key to the future market, which will start growing at the moment when the price of solar panel integration is lower than the price of power generated in this way.
Internal initiatives of many countries favour to such a development of events. For example, the decree of the European Council from 2010, regulated energy efficiency in buildings, will take effect in December, 2020. At this moment, households shall comply with the criteria, stipulating practically zero-energy consumption and cover the power deficit from renewable energies. The decree does not list the sources of renewable energy, but there is a high probability that just BIPV systems will become the base of such kind of energy efficiency up to this moment. Even today, much earlier than the decree of the European Council is effective, many cities worldwide integrate BIPV systems with their buildings. Thus, in April of the current year, the steering committee of San-Francisco, California, took the decision on the use of solar power plants in all new construction projects.
The industry of BIPV systems grows, and set ambitious targets. Newly formed group of companies, Allianz BIPV, residing in Germany, aim to achieve just such a goal: make BIPV systems become a recognised component of the process of building. The group includes small architectural and construction companies. Their representatives are certain that BIPV systems will become an integral part of modern architecture in the near future.
Moreover, when large companies decide to join, it will surely occur.