READY Project Uses Innovative Photovoltaic Modules Developed by the Danish Company RACell
I had the chance to visit the factory and R&D site of RACell, Denmark-based innovative SME providing combined solutions for solar thermal and photovoltaic modules (PV modules) for the demonstrators in the READY project, which is funded by the European Union’s Seventh Framework Programme for research, technological development and demonstration. As I already have heard a lot about their products, I was eager to literally get my hands on their latest developments. We also used this opportunity to throw plenty of questions at the CEO of RACell, Yakov Safir, who responded patiently.
Their first, most important innovation is to laminate multiple bypass diodes inside the module. Bypass diodes are necessary to protect PV modules and maintain total system performance in case of (partial) shading. They are usually placed in the outer junction box. Laminating multiple bypass diodes inside the module has the following three advantages: For one, this invention completely eliminates the sensitive and clumsy junction box found on almost any module, and therefore ventilation behind a module is no longer necessary. Secondly, the module now being a completely flat plate without junction boxes makes it possible to laminate a solar thermal absorber directly on the backside of the PV module. Last but not least, the multiple diodes allow multiple string configurations to match the given system configuration with the inverters even for very large area modules.
Talking of lamination: This is the process of encapsulating the solar cells into a sheet that protects them from environmental exposure to ensure a long and reliable life. At RACell they showed machinery to laminate actual steel mounting profile elements directly inside the large modules together with the cells. This is possible because of patented laminator construction with very large chamber heights. They went on to demonstrate the easy mount invention that simply hooks their modules on any façade by using a lift. This lift operates with suction to attach to a 6m² panel and transport it to a wall prepared with simple L profile rail fixtures. Personally, I find those large panels (up to 3m x 4m) aesthetically pleasing. Furthermore they promise to cut on cost and assembly time at the construction site. The maximum size is limited not only due to limitations in the laminator but also by the maximum height that heavy goods vehicles are allowed to transport under bridges.
Moving on to my favourites, the hybrid photovoltaic thermal modules (PVT modules): They are PV modules with integrated bypass diodes mounted together with an absorber made of multiple thin aluminium finns that are flowed through with water. These PVT modules allow to convert solar irradiation into electricity and hot water simultaneously thus making efficient use of the available space. When laminated together, the PV glass part and the thermal absorber form a load bearing structure which enables them to also act as roof elements. As Yakov told us, they managed to find a process that glues and joins together two materials with differing coefficients of expansion. Regarding the thermal component I would have expected finger thick water channels instead of the 1mm thin metal finns. However, the thinness helps with performance, cost and weight.
Besides managing the balancing act of producing electricity and hot water (PV prefers it cool) at the same time, RACell is currently investigating a further use of their PVT system. You might have experienced yourself how uncomfortably chilly a night sky can be without cloud coverage. The same effect can be utilized with solar thermal modules for cooling purposes by dissipating unwanted heat towards the night sky. This free night cooling could work especially well with thermally inert buildings that use low temperature concrete core activation. In my opinion the challenge lies in the clever design and operation of such efficient buildings and their innovative energy systems. Furthermore, each climate zone requires individual solutions.
We finished our tour with a demonstration of a PV module with integrated LED and programmed light sequences. At first this appeared to me like an advertisement boards or like an expensive toy. At second thought however, a large installation on a modern building with the right animations could look really cool and urban at night.
In conclusion, the biggest surprise of all was that, unlike Henry Ford’s Model T, you can have the PV and PVT panels in almost any colour moving away from the usual blue or striped black panels. Currently they are developing a white (!) panel and I am really curious about the resulting performance. I was promised to see one, the next time I am around. For the time being, I was shown a camouflage-like dark green that supposedly only has a 15% loss on PV production and a little higher impact with regards to thermal output. As an economically thinking engineer I felt a bit unease with the thought of cutting on performance at a supposedly extra charge. However, it could be those innovations that boost acceptance by moving away from pure yield and cost as a benchmark towards creating new aesthetics and integration of renewables with the architecture of tomorrow. Innovation and synergetic use will help with economics.
The large, all black panel with matt surface was my all-time favourite. No way however would I have made it through airport check-in with this panel, nor convinced my darling of the aesthetics of producing clean power over having a flowery spot for sunbathing in our tiny garden. Nonetheless I was able to see some definite want-to-have products. Thank you, Yakov. Now it is time to spread the word and think outside the box - I hope to have given you some inspiration!
Max Blöchle has been working at AIT Austrian Institute of Technology’s Energy department since 2012 in the field of Sustainable Buildings and Cities. During his time in the UK he acquired academic qualification and work experience in the field of embedded electronics and IT systems. With his later study of renewable urban energy systems in Vienna he is now specialized in topics concerning the intersection of Information and Communications Technology (ICT) and energy. During his studies he also gained many years of experience working in R&D for embedded sensors and as a freelancer in IT systems. At AIT he is currently researching potentials of ICT with respect to energy efficiency and integration of renewable energy sources, more specifically working on energy monitoring systems, data analytics and energy management.