Here's my opinion: the price tag is the least useful number on a lighting order. It's the number that shows up on the invoice, but it's almost never the number that shows up on your client's electricity bill, maintenance schedule, or callback list.
I've specified lighting since 2017. I've made mistakes that cost me roughly $14,000 in rework, replacement, and embarrassment. I now keep a checklist so I don't repeat them. The pattern behind those mistakes was always the same: I compared purchase prices instead of operating costs. Downlight globes taught me that first. Zigbee Hue taught me again. Then a grow light made the lesson expensive enough that I finally wrote it down.
The Downlight Globe Order That Cost More Than the 'Savings'
In September 2022, I approved a 47-piece order of downlight globes for an office fit-out. The boxes said 4000K, 900 lumens, 50,000 hours. The price was right: about $4.80 per globe versus $12 for the brand I usually specify. I checked a sample from the first box and it looked fine.
The electrician installed all 47 and turned them on. One corner of the room looked correct. The middle of the room looked warmer. A third section had a slightly green cast. Same product code, same label, three visibly different colors on one ceiling.
It wasn't the bulbs that failed. That's the trap. The cheap globes worked. They just didn't match each other, and in a commercial space, that's a failed installation.
We swapped out 19 of them. The rework cost $580 in labor, plus another site visit and a very unhappy client. The $338 I saved on the purchase turned into roughly $1,100 in total extra cost. Nobody budgets for that line.
Lesson: when you install something permanently, you're not buying one unit. You're buying a batch that has to behave like one system.
Zigbee Hue Taught Me the Same Lesson With Radios
If you follow Signify Philips lighting news at all, you'll notice Hue is always presented as a system. Bridge, app, certified partner products. Not just bulbs. I read that for years and still made the mistake of treating 'Zigbee' as a universal compatibility promise.
Philips Hue uses Zigbee. A lot of other smart lighting uses Zigbee. But Zigbee describes the radio, not the software running on top of it. Think of Wi-Fi: every device in your house uses the same Wi-Fi standard, yet not every device works happily with every router.
The practical version happened last year. I specified Signify Hue lights for a retail fit-out and, to save money on a back storeroom, ordered eight downlight globes from an unfamiliar brand that advertised Zigbee compatibility. They paired. For a few days, everything worked.
Then one globe dropped off the mesh. A bridge restart brought it back. The following week, another one vanished. Then a third. I spent two evenings troubleshooting a project that was supposed to be done. In the end, I replaced all eight with properly Hue-compatible downlights. Cost: $190 more for the lamps, $130 for the electrician's time, and a sore ego.
Lesson: 'Zigbee compatible' and 'works with your Zigbee hub' are different statements. It's not that cheap Zigbee products are always bad. It's that you can't know which ones will behave until they're installed. When you're building an ecosystem, test one first, then buy the rest.
How Much Does a Grow Light Cost to Run?
The third time I made this mistake, someone asked me a direct question: how much does a grow light cost to run? I answered with the same shortcut that failed me before. I trusted the label.
In early 2023, I helped a friend price LED grow lights for a rack of leafy greens. The fixture was advertised as a 600W LED. I calculated: 600W x 18 hours x 30 days = 324 kWh per month. At the US average residential rate of roughly 17 cents per kWh, according to the U.S. Energy Information Administration's Short-Term Energy Outlook, that comes to about $55 per month.
Then we plugged the fixture into a watt meter. It pulled 668W at the wall. The label said 600W; the driver used 668W. My clean $55 estimate became $61 per month. That's fine for one lamp. On a 30-lamp installation, that label error alone is roughly $190 per month that nobody put in the budget.
So here's the formula I use now:
- Find actual wall watts. Use a plug-in watt meter or ask for an independent test report. Never trust the marketing name.
- Calculate monthly kWh: actual watts x hours per day x 30 ÷ 1000.
- Multiply by your electricity rate. In my example: 600W x 18 x 30 = 324 kWh; 324 x $0.17 = $55.08 per month.
But wattage only tells you what the fixture eats. It doesn't tell you how much of that electricity becomes useful light. For horticulture, the useful output is PPF: micromoles of photosynthetically active photons per second. Divide PPF by input watts and you get photon efficacy, measured in µmol/J.
This is the number that actually matters. A budget grow light might deliver 1.8 µmol/J. A modern, well-engineered fixture can deliver 3.2 µmol/J or better. To produce the same amount of usable light, the budget fixture needs almost twice the electricity.
Run the math again with equivalent light output:
- Fixture A at 1.8 µmol/J: about $55 per month in electricity.
- Fixture B at 3.2 µmol/J: about $31 per month for the same plant response.
That's a $288 annual difference on a single light, before you account for one more hidden cost: heat. Watts that don't become photons become heat. In a sealed grow room, that heat has to be removed by ventilation or air conditioning. A less efficient fixture doesn't just waste electricity on light production. It makes your cooling system work harder too.
That's why commercial horticulture brands publish photon efficacy data. Signify's Philips GreenPower range, for example, is sold to growers who understand that the fixture price is the smallest cost in the system. If a vendor won't show you PPF and efficacy numbers, that's a useful answer in itself.
When Cheap Lighting Is Actually the Right Call
I don't want this article to read as 'never buy cheap.' That's not the lesson from my mistakes. The lesson is that purchase price only wins when the light won't be used long enough for operating costs to matter.
Cheap lighting makes sense when:
- The installation is temporary, like a leased space you'll leave in under a year.
- The light runs fewer than a few hours per day, so energy differences are tiny.
- You can replace it easily without paying someone else to climb a ladder.
A 12W downlight globe running four hours a day uses roughly $3 of electricity per year at 17 cents per kWh. Whether it's 10% more or less efficient barely matters. But a grow light running 18 hours a day, 365 days a year, is a completely different financial animal. There, efficiency isn't a premium feature. It's the main product.
The honest rule I now give clients: estimate the payback period. Divide the upfront price difference by the monthly operating cost difference. If the payback period is longer than the life of the installation, buy the cheap one. If it's shorter, buy the efficient one. That's not a moral judgment. It's just arithmetic.
Bottom Line
The cheapest fixture on the shelf is usually the most expensive one in the ceiling. I learned that from 47 downlight globes, from eight Zigbee downlights that wouldn't stay on a Hue mesh, and from a grow light label that overstated the truth by 68 watts.
So stop asking what a light costs. Ask what it will cost to run, how long it will be installed, and how hard it will be to fix if you're wrong. The price tag is just the first page of a much longer bill.