After several years of testing we found out, that the overall energy balance of solar-panels is much better than of a sail. In an average application – holiday boat or world traveller, the energy produced by the solar-panels – which are specially designed for this purpose – exceeds by far the energy produced by the sails for propulsion. It is a simple fact, that you use a sail only a fraction of the time, whereas the solar-panels produce energy every single minute of daylight, energy you can use for propulsion AND for cooking, cooling the boat, refrigeration, washing-machine, water-maker etc.