Ключевые слова: bird, cell, cleaning, dirt, dirty, dust, dusty, efficiency, electrical, electricity, energy, excrement, factory, finger, glasses, hand, hot, loss, low, maintenance, many, mud, palm, pane, panel, performance, photograph, photovoltaic, picture, ratio, roof, rooftop, rubbing, shading, shadow, siam, solar, solar panel, spot, surface, warehouse,