7 more questions worth asking when choosing an agronomic lighting system
Characterizing an agronomic lighting solution is a process that requires answering many questions and making decisions in many different fields.
I explained the basics in three questions in the proper characterization of an agronomic lighting solution. I will address choosing the correct lighting supplier in ask yourself at least 4 questions while choosing your agronomic lighting provider.
In this article we will go one step farther and deeper into the process of selecting the best agronomic lighting system for you. My goal is for you to approach selecting a system with more knowledge and make the correct choices for you. There is a large range of possibilities and solutions available, and the answers to the questions in this article will help in focusing and directing you in checking which system works best for your requirements.
Not everything you need to know will be presented here. However from here you will definitely be able to start the process in, what I feel, is the correct way.For convenience I will present the subject as 7 questions.
1. What type/size of growing facility are you using?
Are you growing in greenhouses, outdoors, aquariums, research facilities, vertical farms, on shelves, vertical columns, on one floor or several?
The answer here will help you to understand the existing limitations of the physical space in placing of lighting arrays, lighting directions, heat emission and more. This can even affect growth protocols and the designated agronomic lighting protocol.
Supplemental lighting in a greenhouse will allow more flexibility with the size of the lighting fixture which, in turn, will affect the heat emission in the facility. When lighting an aquarium we must take note of IP rating, angle of light and minimum distance. In 100% indoor facilities, density has an economic significance which will affect the production capability of the facility and work output. Also, treatment of heat emission is an expense which is highly relevant in growing costs and success.
Answering this question will give you a general idea of which parameters to check and on what to focus.
2. What is the physical shape of the fixture you will use?
Large floodlights, thin linear fixtures, screw-in bulbs, side lighting fixtures?
In most cases, when lighting a greenhouse you can work with physically bigger fixtures with high output, whereas when growing on shelves you will tend to use short fixtures which will take up minimum space on the shelves. When trellising there is a huge advantage in adding side lighting within the foliage. The answer to this question will help you in a preliminary filtering of the solutions that you come across and save precious time.
3. What is the luminous efficacy of the LED?
Answering this question will help you to evaluate solutions by quality.
Luminous Efficacy is the ratio between the amount of electrical energy that the light source uses and the luminous energy output.
The more light units you get per electric unit, the lower the electric cost. Efficacy also equals cash when considering purchasing costs. Components with a high efficacy are more expensive to purchase but cheaper to use.
On the techno-economic side, there is tremendous importance to the heat emission relating to the efficacy. An electric light source converts part of the electric energy to light and the rest to heat.
Let's compare two lighting solutions, for example, XLED and YLED. I'm aiming for a PPFD of 100 micromole/m/second. Let's assume that the energy conversion is 50% light and 50% heat. Let's continue and assume that XLED has a lower luminous efficacy, so, in order to achieve the needed lighting level, with XLED we invest 100w and with YLED we invest 70w (the values are just for example). This means that every hour of use with XLED we put out into the growing space the equivalent of 50w heat and with YLED its just 35w. All this heat needs to be handled by the climate control system which means higher electric costs and can also affect the crop, stress the plants, increase infestations etc.
Pay attention to the luminous efficacy as it is key component in both the facility and your pocket.
4. What is the quality of the components which make up the fixture?
There are a great many components in an LED lighting fixture. I'm assuming that as customers, you don't have labs for testing lighting fixtures so I'd recommend focusing on two main components that are important to check - the LEDs and the driver. Take into account that the quality of the component will affect the lifespan of the product, the ability to maintain a stable spectrum in the long run, light decay, efficacy, heat emission and more.
Your research should include identifying the manufacturer and confirming that it is a reputable company which specializes in producing the components for similar lighting applications to yours.
5. What is the minimum distance from the lighting fixture to obtain spectral uniformity?
In an LED light, the spectrum is obtained from a combination of diodes of different wave lengths. The type of LED fixture and its assembly will affect the distance at which all the different LEDs together will give you the lighting effect and spectrum you want. This will determine the minimum distance from the light fixture at which you will have the spectrum you ordered. Use this to evaluate all the different fixtures being offered in order to find which is most suitable.
COB will generally give spectral uniformity from a lesser distance than individual HIGH POWER SMD LED.
6. Does the fixture have dimming capabilities?
In agronomic lighting I feel that a dimming feature is necessary for almost all applications apart from photoperiodic lighting. When we grow plants from seedlings, during the development we need different lighting levels for each stage of development. We don't always use dimming, however as you get to know your plants and facility the more you'll find the value of it. You will be able to be more precise with your light protocol with changing light levels throughout the growing cycle which will produce better results and save power on light and heat.
7. What is the cooling method?
The weak point of every LED lighting fixture is heat dissipation. A product that can't dissipate heat properly from the junction point of the LED to the electric circuit will not last long and the light will rapidly decay. This may also cause changes in the spectrum.
Check the type of heat dissipation system you are being offered. If there is a solution that removes the heat from the lighting fixture and will also be able to remove the heat from the plants or even from the growing space, this is a wonderful bonus with enormous economic significance both in purchase and growing costs. I've written more in depth about this in my article about LEDs and Heat.
There are many more parameters that need to be researched before reaching a decision about which lighting system will best grow your crop.
Answering the questions raised here will put you on the right path to achieve the successful goal of a system which will provide good results.
I wish you many more questions, honest answers and correct choices.