As part of Wind Up Battery’s push to get everyone thinking about renewable energy, we present, just in time for the summer, a real summer theme: solar energy. Here, it is not a question of photovoltaic cells which convert solar energy into electricity, but of thermal solar installations, that is to say the production of heat using solar heat collectors. Unlike photovoltaic systems where extremely complex physical processes transform the sunlight into electric current, solar heating is within the reach of everyone: the solar radiation which hits the collector is transformed