Ivo Palu, the moderator of the coffee morning, Director of the Department of Electrical Power Engineering and Mechatronics, and Professor of High Voltage Technology, started the event by stating that currently, most of the roofs on campus have no solar panels. He introduced the researchers and research groups working on the development of third-generation solar panel technologies.

Three generations of development

Maarja Grossberg-Kuusk, Director of the Department of Materials and Environmental Technology and Professor of Physics of Optoelectronic Materials, gave an overview of solar panel technologies and the reasons for the need to develop their third generation. Namely, the first generation of silicon-based solar panels, which are currently used most broadly, are produced at a high environmental cost. Second-generation thin-film panels contain materials found in limited quantities or toxic substances; the production of thin-film solar panels based on toxic cadmium telluride is prohibited in Europe. Third-generation panels will be developed to be thin, flexible, partially transparent, economical to produce, and safe and accessible in terms of composition.

In recent years, in addition to the traditional solar panels, the focus has shifted to building-integrated solar panels, where the solar cell is integrated into a building element in such a way that it is not even noticeable. As an example, Grossberg-Kuusk pointed out that Estonia already produces solar panels integrated into building materials – both metal roofs that generate solar electricity and roof tiles that are suitable for buildings under heritage protection. Initially, they will be based on first-generation silicon technologies.

‘Solar energy has been the fastest-growing renewable energy sector for years,’ said Grossberg-Kuusk. However, she added an important nuance: the development of new technologies takes a long time. ‘The silicon-based solar panels we can buy in shops today have been developed for over 70 years; we have only been developing third-generation panels for just over 10 years,’ she points out. Ten years is the minimum time needed to develop new technology, she says, and achieving good results takes even longer. ‘We still have to improve efficiency, which will take another five years for sure,’ said Professor Grossberg-Kuusk in response to a question on how far the third-generation technology is from reaching the market. ‘But a university is not a factory – we will never produce them. We are developing the technologies,’ she quickly added.

Tallinn University of Technology is the only university in Estonia where solar cell systems and technologies can be studied – this makes it possible to use innovation to change the future by solving real problems. New technologies for generating electricity from solar energy are currently being developed in two research groups. Professor Ilona Oja Acik heads the research laboratory for thin-film energy materials, which is developing low-cost, fast, and resource-efficient technology for ultra-thin panels that are well suited to solar power generation on, for example, window panes. The Laboratory of Photovoltaic Materials, led by Professor Marit Kauk-Kuusik, is developing an environmentally friendly and resource-efficient technology for lightweight, flexible, and semi-translucent monolayer solar cells – an ideal solution for building-integrated applications.

In addition, under the leadership of Professor Anna Volkova, the Department of Energy Technology is setting up a solar energy laboratory, which will focus not only on generating electricity from the sun, but also on storing heat with solar collectors. Prof Volkova cited examples from Denmark and Latvia, where fuel-free heat is fed into district heating networks.

TalTech’s ‘roof club’

Kalev Leppoja, Chief Maintenance Officer of the university’s Real Estate Office, said that it is possible to install about 1 MW of solar panels on the roofs of the campus. Leppoja admitted that the university will have nothing left to sell to the grid: with rooftop panels, we can produce 5–10% of our own continuous electricity consumption. However, with the help of solar panels, we will save around 400 tonnes of CO2 per year. Currently, there are panels only on the Ehituse Mäemaja building, which produces about 45 MWh of electricity per year. Leppoja said that the next buildings to get solar panels will be U02 and U05, followed by the Student Building and U01.

Given that the university chose the carbon-neutral path a long time ago, one might wonder why we do not already have panels on our roofs. In theory, we could, but Leppoja presented the practicalities – the stages – of installing solar panels. First, the roofs need to be inspected and thoroughly fixed up – both the roofing and the insulation. Second, the documentation on load-bearing capacity needs to be reviewed – roofs now have to support not only snow, but also panels, and the wind load needs to be considered, too. Third, all plans in the Mustamäe campus must be coordinated with the heritage protection authorities to ensure that everything is the right colour and nothing accidentally peeks over the edge. And finally, building permits need to be obtained from the city government. ‘We have received some money from the ministry for the panels and we will be able to really do something this year,’ Leppoja finished his presentation on a positive note.

Of course, at the same time, the research institution is working with data: every single watt produced by the university’s solar panels is being monitored and, together with the researchers, a suitable environment is being chosen to collect and display the data. So far, three years of data on the electricity consumption of university buildings have been collected in the Campulse environment. In the future, we will also be able to include data on new electricity generation equipment, so we know exactly what the benefits of our solar roofs are. In cooperation with the FinEst Centre for Smart Cities, microgrid management and analysis software will also be developed to act as a bridge between the asset (PV panels, batteries, consumers) and the service provider, gathering data from each and helping the customer to decide whether to consume, generate, or store electricity. This will help the owner of the solar park to better predict their production and to trade more effectively in the market.

At the end of the discussion, Professor Ivo Palu proposed the idea that placing solar panels on roofs could be financed through donations. For example, everyone could have the chance to buy their own panel, monitor its production online, and, if they wish, calculate the electricity price or convert the energy saved into CO2. ‘It would be like a kind of Tamagotchi to keep an eye on,’ said Professor Volkova, drawing an apt parallel. However, a number of questions still need to be clarified, such as who will take care of these ‘Tamagotchis’ over the years – the donors themselves will not be asked by the university to work on the roofs – and whether these costs will be included in the sales price of the panel. ‘Once all the roofs are full and there are still people interested in the ‘roof club’, we will either start giving out grants or make the houses even more efficient, selling, for example, personalised electric windows, wind-resistant doors, and insulated walls,’ Palu joked. Whether or not this is a joke will become clear when the roofs of TalTech are full of solar parks.