Who This Checklist Is For
If you're a commercial grower looking to add Gavita under canopy lights to your setup, this is for you. Maybe you're expanding your vertical footprint, trying to boost yields on lower branches, or replacing older T5 or fluorescent strips.
I've worked with over 200 lighting installation projects in the last 3 years (including some genuinely chaotic retrofits), and I've learned that the difference between a system that performs and one that just creates more problems comes down to three things: compatibility, placement, and power management.
Here are the three steps I now use for every under-canopy light install. Skip one, and you'll likely be re-running wiring or swapping out fixtures later. (Ask me how I know.)
Step 1: Confirm Voltage and Control Compatibility
This is the most common mistake. You see a great deal on a fixture, buy it, and then realize it runs on 120V, but your entire facility is wired for 208V. Or worse, it doesn't play nice with your existing controller.
Gavita under canopy lights are available in multiple voltage configurations, including 120-277V and 208-480V. That's a huge advantage—it gives you flexibility across different facility wiring standards. But you need to pick the right one.
Here's the quick check:
- Check your facility's supply voltage. Most commercial greenhouses in North America run on 208V, 240V, or 480V three-phase. Don't assume.
- Check the fixture's nameplate rating. Not the sales page. The actual sticker on the box or unit. Sales pages sometimes list ranges; the sticker is the truth.
- Check controller compatibility. If you're using a system like TrolMaster (which Gavita units are designed to integrate with), verify the under-canopy fixture is on their compatibility list. This is where you look for specific models, not just brand names.
"In March 2024, I was on-site at a facility that had purchased 50 under-canopy fixtures at a discount. They finally looked at the specs after delivery and realized they were 277V-only. Their entire system was 480V. We had to buy step-down transformers and rewire a sub-panel. The savings evaporated, fast."
Step 2: Map Your Placement (Don't Wing It)
Under-canopy lights seem simple: hang them under the canopy. But where exactly, and at what angle, makes a big difference in uniformity and PAR output at the target zone.
Most buyers focus on the fixture's wattage or claimed PPF and completely miss the light distribution pattern. A high-PPF fixture placed wrong can leave hot spots and shadows, effectively wasting that potential.
What to do:
- Determine your target DLI for the lower canopy. This varies by crop, but for many high-density crops (like tomatoes or cannabis), you're aiming for 15-30 mol/m²/day in the lower zone. Your top canopy lights might be delivering 40+.
- Use a PAR map from the manufacturer. Gavita publishes PPFD maps for their fixtures at specific mounting heights and spacing. Download them. Don't guess.
- Simulate spacing. For most linear under-canopy fixtures, spacing is between 4 and 6 feet apart, mounted 12-18 inches above the target lower canopy. But this is a starting point, not a rule.
- Flag a common blindspot: The question everyone asks is "how many watts?" The question they should ask is "what's the PPFD at the target distance with 6-foot spacing?" That's the number that matters for yield uniformity.
I once compared two layouts side-by-side in a test room—same fixtures, same power, but one with careful spacing and one that was installed "close enough" by eye. The difference in lower canopy PPFD uniformity was over 30%. The careful one won, handily.
Step 3: Verify Power Load and Circuitry
Adding under-canopy lights creates a significant additional electrical load. This is the step most people think they've handled, but often miss a hidden detail.
Your existing lighting circuits are likely already loaded. Adding, say, 50 under-canopy fixtures at 100W each adds 5000W of continuous load. That's roughly 21 amps at 240V. If those circuits were already at 80% capacity, you're now over.
The checklist:
- Calculate the total new load. Add up the actual wattage of ALL under-canopy fixtures, not just a few. Include drivers and any parasitic load.
- Check your panel capacity. Do you have spare breaker slots? Is your main breaker rated for the additional load?
- Consider dedicated circuits. I've found it's often cleaner to run a new sub-panel for under-canopy lighting rather than piggybacking on existing circuits. (Note to self: document this more formally.)
- Don't forget the controllers. TrolMaster and similar systems need their own power and communication wiring. Factor that in.
Based on our internal data from 200+ installation projects, about 15% of retrofits required a panel upgrade or new sub-panel that wasn't planned. Missing that upfront adds both cost and schedule delays—two things no one wants in the middle of a grow cycle.
What Most People Get Wrong (And Why)
I'm not an electrical engineer, so I can't speak to complex power factor corrections or harmonics analysis. What I can tell you from a project management perspective is that the most common failure mode for under-canopy lighting projects is under-budgeting for integration.
You budget for the lights. You might budget for wiring. But you often forget to budget for the time it takes to properly integrate them with your control system, test the PAR uniformity, and adjust placement over the first two weeks. That last part—the adjustment phase—is where the real value shows up.
Oh, and one more thing: if you're comparing against options like Luxx Lighting 1000w DE or other top-end fixtures, don't mix your metrics. A 1000W DE top light vs. a 100W under-canopy LED is not a competition. They do different things. The question is whether the under-canopy lights fill a gap in your total lighting strategy—not whether one is "better."
"What was best practice in 2020—like using standard T5 strips under the canopy—may not apply in 2025. The fundamentals haven't changed (you need light in the lower canopy), but the execution has transformed. We have LED fixtures specifically designed for this now, with better spectra and far less heat load."
So yes, the industry has evolved. Embrace the tools available. But don't forget the basics: compatibility, placement, and power load. Get those right, and the rest is fine-tuning.