Tremendous progress has been made in the science of lighting for indoor farming. We now know about the impact of the light spectrum, the optimal time to operate the lights for specific plants, and much, much more. Despite this important information, all the options on the market today can make picking the right hardware for your specific grow operation a daunting endeavor.
There’s a lot to consider but picking the perfect grow lights for your operation will pay off in spades in the long run.
Here are 10 important factors to consider when selecting the ideal indoor grow lights.
1. Light Intensity
Will the lights provide what your plants needs to thrive? This is where the science comes in. You need to have a basic understanding of the metrics. Understanding factors such as photosynthetically active photon flux (PPF), photosynthetically active photon flux density (PPFD), daily light integral (DLI) and the light spectrum is essential to optimizing the grow environment for your plants so you get the best results.
Cannabis, for example, is a light-hungry plant when blooming. Starting at low levels for cloning (200 µmols) it rapidly climbs to wanting 1,000-plus µmols in later stages. This level of intensity would torch or burn most plants, but not cannabis. If you can keep the carbon dioxide levels in parts per million above your µmol intensity, your buds will grow at their peak speed.
2. Cost
Cost is always a top concern and growers should look at both the long-term and the short-term costs. Less expensive high-pressure sodium lights might seem like the smart path but, when considering operating and maintenance costs, could end up costing more than LED lights in the long run (after one year).
The key expenses to consider are: Investment (grow lights, electrical wiring, air conditioning, automation accessories, etc.); operating cost (energy consumption by grow lights and air conditioning); and maintenance cost (consumables, such as bulbs, and labor, such as replacing bulbs).
For an idea what all these variables would mean to your operation, you can use a cost calculator, like the one at AEssenseGrows.com.
3. Electricity
Voltages can be tricky, so it’s best to talk to an electrician. The choice of voltage has a huge impact on initial building costs. Higher voltage is desirable because you can power more lights for the same current. As a rule, the lower the current draw (less amperage), the easier to install electric wiring.
Wiring, and especially circuit breakers, are limited by the amperage. This will limit the grow lights you can install, so choose carefully. High-voltage feeds (277 volts to 480 volts) are less common but offer the best scalability and are worth investigating.
Wattage is an essential component of cost because it determines how much power your grow lights consume, which translates to the size of your electric bills.
4. Waste heat
Air conditioning is another expense you’ll need to manage as you remove light-generated heat that could damage your plants. The amount of cooling needed is usually expressed in tons, with one ton of cooling being equal to 12,000 BTUs per hour. That’s enough for three HPS lights or five or six LED lights. To figure out your air-conditioning costs, you’ll need to know your cooling efficiency, best measured by the seasonal energy efficiency ratio (SEER), and do some more math to determine air-conditioning costs.
There are a variety of resources available online to help with this. Regardless of the cost, you’ll likely find that the lights themselves consume the lion’s share of energy. Careful planning can help keep air-conditioning costs in check. If you have multiple grow rooms, for example, you can minimize heat generated — and the necessary cooling — by scheduling lighting times to ensure all lights aren’t on at once. Lighting schedules can be staggered for the best electrical rates.
The key expenses to consider are: Investment (grow lights, electrical wiring, air conditioning, automation accessories, etc.); operating cost (energy consumption by grow lights and air conditioning); and maintenance cost (consumables such as bulbs and the labor to replace bulbs). Photo by Steven Conley.
5. Uniformity
There are many plants on each grow tray and it is simply not enough to have the right light intensity in just one point. Every part in the canopy needs to receive the right number of photons. Ideally, your PPFD intensity should be the same everywhere across your complete canopy surface. Otherwise, your results will be wildly inconsistent with large colas here and there and light deficits in the other spaces. Uniform surface PPFD intensity leads to the highest yields per square foot of canopy.
Factors that come into play include ceiling height, light overlap, plant canopy size and lighting form factor.
One way to help ensure uniformity is to get grow lights that fit perfectly over the tubs rather than mixing and matching lights in an effort to get all plants covered.
6. Automation
An automated lighting system where you can control ON/OFF and dimming is crucial for a large operation. It cuts labor costs while ensuring your plants get the light they need to thrive. And by keeping employees out of the grow rooms, automation helps with pest management. Selecting a lighting system that has automation technology already integrated will save you dollars (and perhaps a few headaches) over adding an automation system separately.
7. Form Factor
The dimensions of the lighting units are especially important if space is at a premium in your grow rooms. Regardless of the space you have, thinner, lighter units give you more flexibility and open up more vertical stacking options.
Aisle space is wasted-light dead space. Using movable trays or movable rows enables higher canopy density in your grow rooms. There is also the added benefit of perfectly formed lights as they move with your movable rows and every plant always gets the ideal intensity.
While high-intensity discharge lights may be cheaper initially, the long-term cost of operating the power-intensive lights, as well as cooling them, must me factored into your decision. Photo by Garrett Rudolph.
8. Manufacturer’s backup data
You’ll need to read the fine print to make sure the information provided is relevant to your grow room scenario so you can make an informed decision. This includes factors like installation height, tray area and grouping (light overlap). You’ll want to make sure you’re speaking the same language as the data sheet authors. For example, when you want to understand the power consumption, look for input power, not LED power or bulb wattage.
9. Water resistance
No matter how you grow your plants, there is going to be water involved, and your lights are going to get splashed on occasion. You want to make sure they can take the occasional water splash without leaving you in the dark.
10. Longevity
Check the warranty. A quality light should carry a warranty of at least five years with high output quality. The longer your lights last, the lower the cost of materials and labor to replace them.
Phil Gibson is the vice president of marketing at AEssenseGrows. He has been with the company since 2016 and manages business development and marketing globally for indoor cultivation. He has a master’s degree in business from the University of Southern California and an electrical engineering degree from the University of California, Davis. More information and a detailed white paper addressing the total cost of lights can be found on the AEssenseGrows website.