Solar cells do not depend on weather conditions. First of all, they are 100% water-resistant. Whether it rains or gets foggy – they work if only there is some natural light. Panels work constantly and stably although the darker it gets, the less efficient they become. This is what differs them from windmills fitted on board of boats which, under heavy wind, generate lots of power just to stop working when they reach a place shielded from wind. Such a charging mode does not benefit batteries, which makes it necessary for special charge controllers to be installed. An undoubtful advantage of photovoltaic panels is their noiselessness and reliability – the advantages that windmills unfortunately do not have. Monocrystalline and polycrystalline photovoltaic panels are the most popular ones. Monocrystalline cells work better in focus light, that is when there are no clouds in the sky. This is why they are more often encountered in Southern Europe and Africa. As for polyscrystalline ones, they are better off in stray light. Such conditions are more frequent in our country, cause the Polish skies are often cloudy and clouds act like filters and disperse the light. If we take a closer look at different seasons of the year, monocrystalline modules do better in the summer, but polycrystalline ones are more effective in other seasons. Paradoxically, at our latitude clouds are quite beneficial to photovoltaics, cause stray light makes panel exposure more uniform. You must keep in mind that a photovoltaic module is like a chain – it works as well as its weakest link does. Therefore, if a little cloud appears in a clear sky and casts a shadow over one of the cells, the other ones slow down to adapt to the shadowed one. In such a situation monocrystalline modules shall do worse even if their general capacity is better.