Until the second half of 2010, photovoltaic panels were used very rarely as a source of energy for greenhouses. Due to the opacity of the cells, the batteries could occupy only 10 to 30% of the greenhouse roof area. This limited the productivity of the installations and reduced the amount of light received by the plants. The problem was solved only with the advent of thin-film translucent photovoltaics.
Purple panels by Michael Loic
The first translucent greenhouse batteries to become widely known were the purple panels of a California engineering team led by Michael Loic.
In 2017, an experiment was carried out with two greenhouses, one of which was completely covered with photovoltaic sheets. In both beds, the same vegetable crops were planted – cucumbers and tomatoes – after which they began to observe their growth.
The crop in the tested greenhouses ripened at the same time, and did not differ in the entire set of quantitative and taste parameters. At the same time, the “purple” greenhouse fully provided the needs of plants for electricity for ventilation, heating, lighting and irrigation.
The detailed results of the experiment were published by the American magazine ” Earth is Future “.
Solar panels LUMO
Among the first industrial samples for greenhouse complexes, innovative LUMO panels stand out. In addition to the increased efficiency compared to earlier models, the solar panels of the American company Soliculture were distinguished by the presence of a special luminescent coating on the inner surface.
The physical and technical features of LUMO allowed semitransparent surfaces not only to effectively combine the transmission and absorption of photons, but also to refract the green part of the spectrum into the red. The predominance of this particular wavelength:
- increases the yield of vegetables by 6-8%;
- accelerates ripening time;
- increases resistance to diseases and pests of fruits;
- reduces the need for water by 5%.
To increase the energy efficiency of installations, Soliculture also offers a combination of transparent elements with classic SD photovoltaics. In this case, the first type of panels is placed on the roofs and walls of greenhouses, and the second – in warehouses, where finished products are packed and stored.
French development of Ombrea
The European answer to the Americans was modular photovoltaic systems with artificial intelligence of a sliding type from the French company Ombrea. The specialization of this holding is the comprehensive protection of crops on agricultural farms from climatic threats, including extreme precipitation and temperature fluctuations.
The French have developed a unique design with sliding solar panels, which are controlled by a computer based on information from external sensors. Innovative solar power plants from Ombrea not only provide energy for closed greenhouses and open areas for planting crops. Automatic control allows you to vary the position of the batteries and the amount of incident light depending on weather conditions.
According to the head of the company, Julie Davico-Pajin, his designs:
- guarantee mechanical protection of plants;
- select the optimal level of solar insolation required for different crops;
- contribute to the increase in the yield of greenhouse and melon vegetables;
- allows you to reduce or increase the content of sugar and alcohol in grape varieties, etc.
Batteries with Selective Radiation Absorption Technology WSPV
The most advanced today is the WSPV technology, developed by specialists from the University of Santa Cruz (California), physicists S. Carter and G. Allers in 2019. The prototypes for its creation were the earlier development of Soliculture panels, with which the new technology has much in common.
Batteries with selective absorption of the solar spectrum have the following unique physical and technical characteristics and operational capabilities:
- transmit light waves of one range of the solar spectrum and absorb others;
- due to the presence of a special luminescent coating, they provide a glow at the level of 25% of the maximum efficiency even at night or in thick clouds;
- due to the patented design of current-conducting strips, they minimize losses in the energy conversion process;
- in 80% of cases provide a higher rate of crop maturation and yield growth;
- require 5% less water for irrigation.
Selective separation of electromagnetic radiation makes it possible to provide sufficient illumination to plants without reducing the efficiency of photovoltaic installations. For greenhouses, this technology is ideal.
Benefits of Translucent Batteries
The ability to increase yields is only one side of the coin that distinguishes WSPV panels and the like. The second contains a number of economic advantages, in comparison with both previous generations of photovoltaics and traditional energy sources for greenhouses. Among them are the following advantages:
- Translucent solar panels are 35-45% cheaper than “classics” of similar performance.
- Light weight and unique optical characteristics allow them to cover any usable area without compromising the lighting of plants.
- The capacity of the plants is enough to cover 100% of the needs of greenhouses for heating, ventilation, irrigation and electronics control in sunny regions, and up to 90% in the middle lane.
If it is necessary to increase the autonomy of the greenhouse on cloudy days, it is possible to reconfigure the absorption range upwards. The increase in productivity will be achieved through the partial selection of red light waves that promote photosynthesis. Plants at such times will grow a little slower, but this will not affect the overall yield.