M. Grafiadellis, G. Spanomitsios, K. Mattas
Among the big variety of solar systems for heating greenhouses developed in different countries, the passive solar system with water tubes designed in Agricultural Research Center of Northern Greece has been found to be the most acceptable for practical applications by the growers. The reason is that this solar system is very simple in its construction and also is very effective in the use. With this system the solar energy is collected in the greenhouses by laying water tubes between plant rows. The same water tubes are used as heat reservoirs and also to distribute the energy collected. Under the water tubes a black sheet of polyethylene film is laid to increase the efficiency of the system and to avoid weed growth.

From the research data collected during 1977–1988 on this solar system it was found: a)The most suitable plastic material for the construction of the water tubes is a good quality simple polyethylene film 100–125 μ thick, b)The best size of the water tubes is that of 100–120 cm. perimeter, c)The water tubes should cover 35–40% of the area of the greenhouse, d)This system increases the air,l the soil and the plant temperature by 3–5 °C and affects considerably plant production.

Grafiadellis, M., Spanomitsios, G. and Mattas, K. (1990). RECENT DEVELOPMENTS INTRODUCED IN THE PASSIVE SOLAR SYSTEM FOR HEATING GREENHOUSES. Acta Hortic. 263, 111-120
DOI: 10.17660/ActaHortic.1990.263.10

Acta Horticulturae