Every day, the Earth receives enough energy from the Sun to fully meet all human energy needs all over the world. Photovoltaic solar panels have been developed to capture this energy as electricity and solar thermal collectors are used to produce heat. While the efficiency of such system has been increasing and prices decreasing, the fundamental problem of only having solar energy available during daytime remains. Solar thermal energy can be stored in water tanks for a few days, but in the Nordic countries very little solar energy is available during winter.
While infeasible for single houses, in community scale the solution is seasonal energy storage. In our project Tackling the challenges of a solar community concept in high latitudes, we propose a system where a large amount of solar heat is collected in the summer and stored in the ground, to be used many months later during the dark of winter. In Europe, dozens of solar communities already exist, with Denmark being the forerunner. In Finland, however, only two major trials have been made. These projects were not major successes, due to design errors, insufficient technology development or lack of ambition. Today, there are examples of fully working solar communities, most famously the Drake Landing Solar Community in cold Canada, which provides 98% of its space heating demand through solar power.
Just copying a pre-existing design is not enough, however, and any design of such a solar community has to be adapted to the local conditions. This includes the availability of solar energy and properties of the ground, as well as economic, legislative and social aspects. To design a practical solar community concept, this project is made as an interdisciplinary collaboration between four different teams, each focusing on a work packagerelated to one important aspect of the problem.
Work package 1 (Aalto University, Department of Energy Technology) is focused on the energy system in the community, designing the interconnections between energy generation, consumption and storage.
Work package 2 (Aalto University, Department of Civil and Environmental Engineering) is studying the feasibility of different seasonal storage concepts, designing and modeling the most optimal concepts.
Work package 3 (Hanken School of Economics, Department of Marketing) is focused on the business models of the community, what kind of pricing or investment schemes work best in such a shared system.
Work package 4 (University of Helsinki, Department of Social Research) is looking into the social acceptability of the solar community, how to get past peoples' resistance to a new kind of technology and living environment.
To ensure the practicality of the developed concepts, an advisory group of industrial partners will be formed. This group will provide advice from companies which work on fields related to the solar community design and construction.
At the end of the project, we aim to have a practical concept of a solar community, which will provide more than 90% of its annual space heating and hot water demand through solar energy. The design should be economical and socially acceptable, so that there is nothing preventing actually building the community for people to live in.
Text: Janne Hirvonen