Double layer glass with built-in solar cell is installed on the roof of the dryer, under the outside air is circulated, and underground heat exchanger device employing heat exchanger pipe embedded in the ground By introducing the heated hot air into the lower part of the dryer and circulating, a low-temperature dryer using economical and environmentally friendly solar heat and geothermal heat is possible, which enables high efficiency drying of crops. A horizontal auger 20 is disposed inside the low temperature dryer, and a plurality of wings 22 spirally move on the radial axis of the rotary auger 20 of the horizontal auger 20 in contact with the agricultural products to transfer the agricultural products in the transverse direction. Is formed to protrude, the horizontal auger 20 is rotated by a drive motor 24, the solar cell generator 100 is installed on the roof of the low temperature dryer, a plurality of solar cells 130 is built A glass plate 114 is installed on an upper surface of the battery module 110, and a first air flow path P1 for warming by solar heat while circulating outside air is defined between the inner upper surface of the main body and the upper guide plate 16. The second air passage P2 for circulating the air heated by the geothermal heat is defined between the inner lower surface of the main body and the lower guide plate 18, and the air heated by the geothermal heat is transferred to the second air passage P2. Underground heat to provide toward The ventilation device 200 is provided with a heat exchange pipe 210 is made of a long pipe in a zigzag form so as to obtain the heat of the ground effectively.태양전지가 내장된 복층유리를 건조기의 지붕에 설치하고 그 아래로 외기를 도입하여 순환시킴과 동시에 지중에 매설된 열교환 파이프를 채용한 지중 열교환기장치에 의해 10~35℃의 천부지열을 이용하여 데워진 더운 공기를 건조기의 내측 하부로 도입하여 순환시킴으로써, 농작물의 고효율 건조가 가능하여 경제적이고 친환경적인 태양열과 지열을 이용하는 저온 건조기가 개시된다. 저온 건조기의 내부에는 수평오거(20)가 배치되고, 상기 수평오거(20)의 회전축(21) 방사상 외면상에는 농산물과 접촉하여 농산물을 횡방향으로 이송하기 위한 다수의 날개들(22)이 나선형으로 돌출하여 형성되며, 상기 수평오거(20)는 구동모터(24)에 의해
