DC in the Greenhouse



DC in the horticulture

The greenhouse market is widely using HID lighting fixtures to illuminate the crops. When using supplemental lighting based on AC, a lot of energy is wasted in the conversion of AC into DC in each lighting fixture. This energy loss is converted into heat waste in each fixture. If the entire greenhouse would use DC, these losses would be reduced. By centralizing conversion of AC to DC in the greenhouse, instead of local conversion in each of the lighting fixtures, a lot of energy would be saved. 

DC and SON-T

Block diagram of the HID lamp connected directly to DC:


Currently used AC driver:                                   Prototype DC driver:

Input voltage 1ph 400Vac 50Hz

1000W SON-T

Driver from Philips

Efficency: >96%

Power factor: 0.98

Input current: 2,6 Aac

Wire  3x 2.5 mm² + PE max. 9 lamps

Wire 3x 4 mm² + PE max. 15 lamps



Input 700Vdc

1000W SON-T

PCB mounted in a Philips case

Power Line communication

Efficency: >98%

power factor: NA

INput current: 1,4 Adc

Wire 2x 2.5 mm² + PE max. 11 lamps

Wire 2x 4 mm² + PE max. 18 lamps

System overview

The block diagram below makes clear that central distribution panels belong to the past and are to be replaced by a local connection to a DC bus where communication and energy go together.


Direct Current Ltd also sponsors this project Gelijkspanning Komt in de Kas (DC in the Greenhouse). Direct Current Ltd gives technical support for the development of the DC infrastructure and the development of DC lighting fixtures in the greenhouse.

The following organizations displayed in the image on the right side are also sponsors of this project. For more information, please visit the website of DC Foundation at www.gelijkspanning.org. In the Hague College, we have initiated a program in cooperation with the DC Foundation in order to motivate students to work with DC and to teach the subject of DC.



Direct Current Ltd is developing for the greenhouse market a DC version of the currently used HID ballast.

In addition, a new standard is being developed for the DC infrastructure with the following starting points:

  • Less material
  • Higher system efficiency
  • Longer life span
  • Future-proof
  • Hybrid SON-T and LED lighting
  • Lower operating costs

Project sponsors

The following companies are sponsors and partners in making DC in horticulture possible: