Solar thermal evacuated tubes
Solar thermal evacuated tubes are made from strong, insulated glass and contains a copper heat pipe which heats up when there is sunlight on it.
Evacuated tube systems are very efficient and they can collect energy even in overcast or cold weather.
Due to the cylindrical shape, evacuated tubes are able to collect sunlight for many hours of the day. With a series of tubes ideally on a south facing roof, you can maximise the heat conversion as the sun is at the best angle to the surgace of the for much of the day.