Want to install or upgrade your auxiliary lights? This is a step-by-step guide to help you determine the best fit for your needs.

Lighting is one of the most expensive and important decisions in controlled environment agriculture (CEA), whether in a greenhouse, indoor farm or vertical farm. However, lighting technology continues to develop rapidly, resulting in a large number of options. So how do growers choose the right light? This article gives the answer.

The following are some important growth lamp terms:

In the best case, the right plant grow lights can optimize output, reduce operating costs, and keep up with the evolving market.

1. Define operational goals. Do you want to maximize yield, quality or flexibility between crops? Do you want to minimize investment or maximize return on investment? Due to the large number of lighting products on the market, determining your operational goals will help you first narrow the range of available technologies to candidates that best suit your needs. Over time, output and quality may need to be continuously optimized, and understanding your operational goals will tell you which technical specifications to pay attention to. After understanding your goals, you will be able to ensure that your plant growth light solution not only meets your initial needs, but is also flexible enough to continuously optimize your most important parameters.

2. Determine the target lighting requirements. Lighting may require 5 to 10 years of capital investment, so plan for the future. For example, if you know that you are starting to grow leafy greens, but plan to grow grape crops within two years, consider building your system to accommodate crops with higher light requirements.

Then, you can determine your lighting goals based on the following parameters:

Strength (PPFD, DLI): Which of your crops requires the highest PPFD or the highest DLI? Specify your system to meet the needs of your most demanding crops now or in the future.

To find the recommended crop PPFD or DLI, look for proven agricultural resources and manuals, for example from Purdue Extension (extension.purdue.edu/extmedia/ho/ho-238-w. pdf).

Spectrum: What kind of wavelength distribution do you need?

Broad-spectrum lamps with a fixed output can usually be used to produce high-quality plant growth in a range of crops, but more advanced lighting systems can adjust the spectrum according to specific needs.

For example, if you get the most commercial value from budding or flowering products, you might focus on a system that enables you to adjust the ratio of red to far-red light at different growth stages. However, too much red light may falsely signal to the plant that it is being shaded, triggering shade avoidance mechanisms, such as extending or changing the flowering time, which runs counter to your crop goals. In contrast, the correct ratio of red light to far-red light allows you to trigger flowering when needed. If optimizing photobiology through the growth cycle can increase commercial value, tunable spectral illumination may be a feature to consider. See g2voptics.com/photobiology/ for more information on the subtleties of photobiology.

Uniformity: What is often overlooked is whether your light is uniform. Will one plant become saturated while others lack light? Although you can ensure that plants are properly illuminated by placing them under the fixture, the design of the fixture determines how much flexibility you have when placing crops while still achieving a certain uniformity of lighting. Check the manufacturer's uniformity and lighting specifications to understand the distance and acceptable angle to achieve a specific PPFD. Unification is achieved through the combination of plant growth lamp specifications and overall room design, so some lamps cannot be used in conjunction with your expected growth environment.

Coupling: This is another factor that is often overlooked in growing lights—how much light actually reaches the plant (reported as a percentage)—it depends on the light specifications and layout design.

Many layouts allow 30% of the light to spill into the aisle, which does not contribute to plant growth. This is wasted funds and increases your operating expenses. The degree of coupling between light and plants depends on the shape of the canopy of the plants, as well as the emission angle and distance of the lamps. If you grow on a single-layer connected table, the coupling degree of the wide-emitting lamp will be high (95%). However, if you plant on a rack with a walkway in the middle, the height of the rack lighting will greatly affect the amount of light loss. If your rack lighting is quite high compared to the plant canopy, the wide emission lights will result in a lot of waste of electricity when illuminating the sidewalk. If you install multi-level rack lighting near the plant canopy, there will be less spilled light loss. Check the specifications of the corner emission, and whether the lamp has a lens, and compare them with your expected layout. See how much your lighting investment will help plants grow.

The total lighting area, the lighting area of ​​a lamp, and the price of a lamp are typical up-front costs that operators will consider. But this is not enough.

In addition to direct costs, lighting also involves indirect operating costs, such as HVAC, ongoing labor and management overhead, not to mention degradation, replacement and obsolescence costs.

3. Determine the total area you need to cover. What is the total area of ​​your crops? How big is your expected leaf crown? Are you willing to accept the lower quality of light around you?

In general, do not include the area of ​​walkways and benches in your estimate, but this will depend on the shape of the room. When you plant on a shelf, only the shelf is important, but when it is a large single-story canopy room, the aisle is usually (unintentionally) illuminated by light and may have to be included in the area. A good way to avoid this situation is to use a scrolling table. Generally, you want to cover as much growth area as possible compared to the circumference, because correcting for unevenness around the circumference of any growth operation can become expensive.

It is also worth considering some options, such as accepting poor light uniformity at the edge of the production area and compensating for it through crop rotation. For example, some growers will deliberately choose lights that illuminate areas smaller than the plant canopy, and then rotate the plant's position throughout the year. If the lights are more expensive than the labor required to move the crops regularly, this can save costs.

The total area you want to illuminate, and the lighting quality of each area you want, will help drive the number of lights you need, and the types of lights that may be based on the total cost.

4. Finding and designing different lighting options With your requirements, you can now focus on finding lighting. Consider several different technologies so that you can evaluate the widest possible range of products.

For example, although high pressure sodium (HPS) and ceramic metal halide (CMH) lamps are very common in horticulture, LED technology now offers significant competitive advantages, including energy efficiency, longer service life, and different lighting formulations. A variety of adjustable settings. Once you have narrowed the range to several types of plant growth lamps according to the specifications, you can use their parameters to design detailed layouts and lighting studies to verify your assumptions about the number of lamps, uniformity and coupling .

Make sure you understand the cost and features provided by each option.

5. Estimating the benefits Many times, growers only focus on one aspect of lighting-a cost that needs to be minimized. This may become a missed opportunity to maximize operational value.

Photons are the main driving force of photosynthesis and therefore are the result of cultivation. Lighting should be seen as an investment in infrastructure to maximize operational output.

Most commercial farms are driven by the annual crop income per unit area, which is calculated based on the sales price of the crop, the output per unit area, and the number of harvests in a year. All of this depends largely on the quality of the lighting. Better quality light can increase sales prices, increase yields, or shorten harvest time. Light intensity, spectrum, uniformity, and most importantly intelligent light management, can all drive cultivation value.

Smart light management uses data to determine the spectral intensity and lighting duration at any point in the plant life cycle. In small facilities and the early stages of growth, light management can be achieved through manual monitoring and manual control by experts. However, in large commercial facilities, it is best to achieve light management through real-time monitoring and an intelligent light management platform. This kind of automation platform is becoming more and more commercialized.

However, it is difficult to estimate the quantifiable benefits of high-quality lighting, such as annual crop income per unit area. For growers who are not familiar with specific crops, please talk to the Growers Association and view the Federal Agricultural Yield Report to understand the expectations for a certain crop. From this, you can estimate the rough benefits of crop growth, but you may not be able to compare different options.

To compare different lighting options or conditions, the best way is to experiment and verify. Don't build the entire facility based on theoretical output! Instead, spend less money and conduct experiments to accurately assess whether a 30% higher PPFD can recover the cost in terms of revenue.

Pilot studies can be time-consuming, but they are essential for exploring the benefits of specific grow lights. Successful pilot studies depend on working with trusted partners throughout the optimization process.

6. Estimate the initial purchase cost (obvious cost) The number of purchased lamps comes down to the total lighting area required, the lighting area of ​​one lamp and the price of one lamp. This is the obvious cost that most growers will consider, as well as the cost of electricity to run the lights.

7. Estimate other less obvious costs. Lighting is closely related to the complex production equipment required by CEA. Although the initial purchase cost is important, in reality, any gardening operation requires:

For example, the up-front cost of planting lights is lower, but they generate too much heat. Although the initial capital expenditure may be lower, the cost of the HVAC system may increase to manage the higher heat load during the summer. Cheaper bulbs may also be prone to failure, resulting in ongoing maintenance costs. The least obvious is the cost of degradation. Over time, all lights will degrade, resulting in a decrease in light yield and revenue.

Labor can also be expensive. Although lower cost options may require personnel to enter and manually turn some lights on or off, more expensive lighting solutions may be automated. Make sure you have seen the broader picture and considered any hidden operating costs.

8. Calculate the return on investment and payback period You now have everything you need to calculate the return on investment (ROI) and payback period. Generally speaking, ROI is calculated by dividing the sum of benefits by the sum of all costs (including all indirect and potential hidden costs) during the time period of interest.

To give a very simple example, suppose there are two different lighting systems: the capital cost of system A is 75,000 US dollars, the annual operating cost is 10,000 US dollars, and the estimated annual output value is 100,000 US dollars. In comparison, the capital cost of System B is US$100,000, and the annual operating cost is US$15,000, but it is estimated to be able to produce US$125,000 per year. The second system is essentially equivalent to an increase of 33% of the upfront cost, 50% of the operating cost and 25% of the production capacity.

On the surface, a lower-cost lighting system may provide more value in the short term. However, a 25% increase in long-term gains would have a significant impact on the USD 25,000 investment difference between the two systems.

After five years of additional capital investment of $25,000, you can calculate a simple rate of return on the marginal difference between the two investments:

[(5 years of additional income)-(5 years of additional cost)-(additional capital investment)]/(additional capital investment). The annual additional income is US$25,000 and the annual additional cost is US$5,000. Therefore, the simple return on investment is [(5 x US$25,000) – (5 x US$5,000) – US$25,000]/ US$25,000 = 3 (or 300% return on investment!).

The payback period is calculated as (investment amount)/(estimated additional cash flow), or in this case (additional capital investment)/(additional annual income – additional annual cost) = (25,000 USD)/(25,000 USD – 5 thousand U.S. dollars) = 1.25 years.

Please note that these are highly simplified examples that do not include some of the more important aspects, such as light attenuation and changes in yield over time. However, these examples do illustrate some of the key principles we describe throughout this article, and that the best lighting solution is not necessarily the most obvious solution.

Be sure to work with a financial expert to develop an appropriate financial model, including the time value of funds and the cost of capital, to capture the nuances and maximize the return on your precious lighting investment.

This article describes lightweight profitability, but experts can help you learn more. If you have any questions, please contact a promotion expert or lighting professional, and read more about indoor planting at g2voptics.com/horticulture-lighting.

Master Hal Friesen is the head of the R&D team and technical communication expert, and Dr. Ryan Tucker is the CEO of Edmonton G2V Optics. G2V is known for producing some of the most advanced commercial lighting and surveillance products suitable for renewable energy, aerospace and controlled environment agricultural applications. You can contact them at info@g2voptics.com.

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