"In our view, the only logical option is to use LED"

Half of the HPS fixtures at the Belgium tomato nursery Primato have been replaced with LED toplights, allowing both intensity and spectrum control. Kevin Primato explains, "Now we can maintain the same light levels with half the lamps as we did with the HPS before. We aim to use 80% LED and 20% HPS."

Primato's greenhouses look completely different from last year when the new tomato plants were yet to arrive. Due to electricity prices, the company opted for unlit cultivation then. Kevin says, "We occasionally supplemented with SON-T lighting when electricity prices were low, but it was certainly not fully lit cultivation." Now, with tomatoes already showing good fruit growth, the situation in the greenhouses has changed. "Due to customer demand, we wanted to reintroduce lighting. In our view, the only logical option is to use LED," says Kevin.

Primato is known for its investments in sustainability. During the 2017 expansion, when the greenhouse was expanded to 12 hectares, half of it was equipped with 180 mmol SON-T lighting. Part of the lit area was then fitted with a hoistable LED interlighting installation of 75 LEDs. "We're keeping that," Kevin points out. "But half of the HPS fixtures have been removed and replaced with LED fixtures. Transitioning to full LED is a significant step, and we have the lamps available. In a new greenhouse, we wouldn't use HPS anymore, but now we can gain knowledge. Then we can decide whether to replace the rest in the coming years and redistribute the fixtures over the next few years."

The 1000W HPS has been replaced by a 1000W LED. "When the HPS is off, and the LED is on, we achieve double light levels compared to the HPS. So now, with half the lamps, we can maintain the same light levels as with the HPS before."

They chose a model with the widest possible lens for the highest possible uniformity. Initially skeptical about good light distribution with such an arrangement, they found it to be effective. The choice also fell on Mechatronix lamps for various reasons. The 3100 toplights installed can be controlled on three channels: the red, blue, and white spectra can be set separately. The entire installation is dimmable. Due to multi-channel control, they also have a boost function where they can go up to 1250W. This is possible only when the HPS is off due to the load on the strands and the transformer.

"We deliberately chose to invest more now. We believe we will get more out of it in the long run," says Kevin. 'When there is sufficient daylight, or when there is no staff in the greenhouse, we turn off the white light. We also do this when the HPS lamps are on because this spectrum is abundant in the HPS range. This way, we can optimize energy consumption."

Moreover, the HPS lamps are still used. "We heat with the CHP, but sometimes we can use the radiation in the crop head. Last week, for example, when temperatures were low. With HPS, it's also a bit better for dehumidification, and we can lower the pipe temperature by a few degrees. It means a little less heat goes into the bottom net. HPS may be a bit less efficient, but the heat is not entirely lost." At the same time, the company is already experiencing the benefits of LED. "Especially on milder nights and when the screen cloths are closed, it's nice to be able to illuminate with LED alone."

So, there are many possibilities, and it takes some getting used to. "It doesn't make things easier," Kevin confirms. "We try to automate as much as possible and use sensors, but we are still learning, and that means we still tweak a lot ourselves. At the same time, we see HPS as not a solution for the future, and that's why we made this investment. We believe in LED lights."

The goal is to get 80% of the light from LED and 20% from the HPS installation. "We can't grow at the cost level of 3 to 4 years ago. Energy prices have dropped in recent times, but it's still much more expensive than a few years ago. Yet, there is a demand for winter production. We do everything to save energy, but it must not compromise the cultivation. That still comes first."

For more information:
Primato
www.primato.be
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Kevin Pittoors
[email protected]