TOTEM: A low-cost solar-powered aeroponic system for vertical agriculture.

Soil degradation, freshwater scarcity, and urbanization are increasing the demand for resource-efficient food production systems. Controlled environment agriculture (CEA), particularly aeroponics, enables efficient crop production with reduced water and nutrient use; however, most existing systems rely on grid electricity and involve high implementation costs. This work presents TOTEM, an open-source, solar-powered vertical aeroponic system implemented for energy-autonomous soilless agriculture. Developed for universal replication, the design allows for modification or scaling using widely available materials. The system integrates a modular stacked architecture comprising growth, reservoir, pumping, filtration, control, and power units. A microcontroller-based embedded controller manages irrigation cycles and monitors chamber temperature and nutrient solution level, whereas a photovoltaic module enables fully off-grid operation. The system was built to support up to 24 plants within a compact footprint (0.078 m3) and validated using basil (Ocimum basilicum) under two successive harvest cycles. Results demonstrated stable irrigation performance, uniform nutrient distribution, and reliable operation on solar power. Biomass production confirmed the system capability to sustain plant growth under continuous operation. TOTEM provides a scalable, low-cost platform for vertical farming with applications in urban food production, research, and education, particularly in resource-limited or off-grid environments.