Gross collector area (m²)
Annual collector output / m² in Athens at
|Vitosol DIS20A||Flat plate|
|One Sun One|
The One World Solar Collector developed by Austrian company Sunlumo finally received a Solar Keymark certificate in October 2015 (see the attached PDF). This is a milestone in the long design and development process, which started in 2009. “We designed a completely new collector model optimising weight, performance, logistics and raw materials,” Robert Buchinger (left), Managing Director of Sunlumo, says about the long term R&D project. The photo, which was taken at machinery supplier Fill’s booth at the 2014 edition of Fakuma, the international trade fair for plastics processing, in Germany, shows Buchinger and Wilhelm Rupertsberger, Head of Competence Center Polymer Technology at FilI, holding up the pilot collector with a gross collector area of 0.95 m² and a weight of only 8.1 kg. Sunlumo is looking for investors who want to purchase a complete production line as well as the license and produce the polymer collector locally. The One World Solar Collector is the third 100 % polymer collector with a Solar Keymark certificate. The other two are Eco Flare 3M by Israeli manufacturer Magen Eco Energy and a collector from Norway’s Aventa.
AIT Austrian Institute of Technology has performed the tests according to the solar collector standard EN ISO 9806 and took three units from the initial batch. “The initial batch consisted of the production and assembly of several hundred collector components,” explains Buchinger. Since Sunlumo is mainly a service company with a focus on R&D, industrial design and international consulting, its owners established a 100 % subsidiary called One Sun One World, which produced the new polymer collector for the pilot project. This means that the newly founded subsidiary is also the owner of the recently issued Keymark certificates. According to Buchinger, the assembly process of the initial batch from purchased components took place at different sites across the region around Perg, where the headquarters of Sunlumo are located, as well as Linz, the closest larger city.
Low price offsets – smaller solar yield
“We aim at utilising the collector in pumped solar water heaters in sunny countries to challenge thermosiphon technology, which is dominating world markets today,” confirms Buchinger. The designer of the polymer collector limited the maximum operating pressure to 2 bar, which is not enough for a typical open-loop thermosiphon system linked directly to the water grid.
“The absorber consists of a special polymer, which offers high absorption rates, but does not need any additional absorption coating.” The weak points are the higher heat transfer losses caused by the minimised insulation and the high emissivity of the absorber. According to Buchinger, the collector can still compete economically with thermosiphon systems in many climate zones all over the world. The managing director assumes production costs to be 50 % lower than for metal flat plate collectors. Sunlumo is also about to develop polymer components for the solar circuit and considers the cost-saving potential of the entire system to arrive at a total of 70 %, including the lower collector costs.
Nominated for ecodesign award
Since 2012, Solar Keymark certificates include an additional table which enables the comparison of annual collector output in different weather conditions. Domestic hot water preparation in sunny climates corresponds best to the calculations for Athens at an average collector temperature of 50 °C (see the table below). The comparison shows that the better flat plate collectors produce around double the kilowatt hours of the Sunlumo polymer collector, but that the two Chinese vacuum tube collectors achieve only around 40 % more than the One World Solar Collector.
Figures taken from the second table of Solar Keymark certificates for different collector types. The annual collector output was that of Athens at an average collector temperature of 50 °C. The Aventa certificate contains the following statement “Due to a much better aperture–absorber ratio for full-size collectors and the higher flow rate used, a higher thermal performance is expected for actual installations.” The Israeli collector from Magen is not part of the listing, because its certificate does not yet include an additional table.
The modern design of the new polymer collector also convinced the jury of the Ecodesign award presented by the German Federal Ministry for the Environment. Together with 33 other projects and products, the One World Solar Collector was nominated out of 137 preselected applications in four different categories: Product, Service, Concept and Young Talent. The award ceremony will take place in Berlin on 23 November 2015.