Light distribution in a two-level unit with supplemental LED lighting in a hydroponic greenhouse

Plant growth in a multi-level-controlled environment allows intensive cultivation with minimal use of land and water resources.
Modern plant factories are usually fully equipped with modifying LED lights (adjusted to specific crops and growth stages), hydroponics, and intelligently designed climate control and fertilization systems, to reduce the risks of yield loss.
However, multi-level plant factories are not widely utilized due to high investments, energy consumption and complex design.
The current study aims to demonstrate that effective sharing of sunlight between plants grown in a low-cost, two-level system can reduce the needs for supplemental lighting and prevent heat overload, thereby decreasing energy consumption.
Utilizing the structure of a commercial hydroponic greenhouse for leaf crops located in the central part of Israel, optical and thermal models have been employed using ANSYS software to explore the design of the second growth level made of growth channels.
Based on the modeling results, the hydroponic growth channels were installed 1 m above the conventional hydroponic tables.
Growth experiments were conducted with four types of lettuce cultivars, examining the effect of supplemental artificial lighting combined with sunlight.
Several growth cycles were carried out over one year with and without supplemental light treatments.
This study demonstrates that it is feasible to double the growing area without yield loss by spreading the growth channels above the growth tables and using LED lighting to compensate for the reduction of solar radiation.
Alternatively, it is possible to increase the growth area by about 50%, without supplementing lighting, while still maintaining recommended growth conditions.

International Symposium on New Technologies for Sustainable Greenhouse Systems: GreenSys2023

H. Vitoshkin, M. Sacks, L. Rosenfeld, E. Ziffer, V. Haslavsky

multilevel greenhouse, hydroponics, lettuce, optical, thermal modeling

https://doi.org/10.17660/ActaHortic.2025.1426.61