When I first started scaling up our indoor operation, I assumed upgrading every light fixture to the latest full spectrum technology—like ViparSpectra full spectrum LEDs—was the obvious move. Get better spectrum, get better yields, right? I almost budgeted $12,000 for a full facility retrofit in Q1 2024.
Two ROI calculations and a conversation with a grower who’d done exactly that—and regretted it—later, I realized I was dead wrong. There's no single "best" light. It depends entirely on what you're growing, your space, and your budget.
How to Decide: Three Scenarios for Your Grow Light Upgrade
Here's how I now approach any lighting decision. It breaks down into three distinct scenarios:
- Scenario A: You're starting fresh in a new, dedicated space.
- Scenario B: You have an existing setup with older HPS/MH or blurple LEDs.
- Scenario C: You're expanding a current operation on a tight budget.
The mistake most people make is lumping all three together. Let's look at each separately.
Scenario A: Starting from Scratch
If you're building a new room or tent, and you have the budget for new equipment, do not buy outdated technology. This is the one time the upgrade is a no-brainer. Spending $280 on a ViparSpectra P1000 or $320 on the ViparSpectra XS1500 Pro is cheaper in the long run than buying a bunch of used blurple panels.
Why? Start with the electricity. A full spectrum fixture like a ViparSpectra pulls about 150-200W actual from the wall but covers a 2x2 or 2x4 area better than a 300W blurple light did. The efficacy is just higher. ViparSpectra full spectrum fixtures use Samsung LM301B or similar diodes, which hit over 2.7 µmol/J. Most older blurple tech is below 2.0 µmol/J. Over a year of 18-hour veg and 12-hour flower cycles, that difference adds up. In our facility, when we switched our new veg tent to full spectrum, our electric bill dropped 18% for that table alone.
Moreover, the spectrum is just more versatile. A single ViparSpectra 1200w led grow light (which draws around 260W actual) can take a plant from clone to harvest. You don't need separate veg and bloom switches. That simplicity saves you labor and switching errors.
Here's the honest limitation, though: if your space is under 2x2 and you're only growing lettuce or herbs, a full fixture is overkill. A basic T5 or a small blurple panel for $50 is fine. But for anything more serious—tomatoes, peppers, cannabis—start with full spectrum.
Scenario B: Retrofitting an Existing Setup with HPS/MH or Blurple
This is the trickiest one. Look, I'm not gonna tell you to rip out your 1000W HPS system and throw it in the trash. That's expensive, wasteful, and the HPS still works. But I will say this: if you replace a 1000W HPS with a ViparSpectra full spectrum LED pulling 260W, and you run it 12 hours a day in flower, you save about 740W per hour. At $0.12/kWh, that's about $0.09 per hour per light. Over a 9-week flower cycle, that's $68 per light in electricity savings alone.
I did this math for our facility in 2023. We had 12 HPS fixtures in our flower room. The annual electricity savings alone from switching to LEDs was $8,400. That's a full 17% of our annual energy budget.
BUT—and this is the reverse validation part—I only believed the numbers after I ignored the advice initially. I assumed the heat from HPS helped keep my room warm in winter, saving on heating costs. I was right about that. The heat from HPS actually helped maintain temps. When we switched to full spectrum, we had to add a small heater in January. That cost about $120 in extra gas over 3 months. Net savings were still $8,280, but I almost made a bad decision because I didn't account for that.
So: if you have HPS and you're in a cold climate, factor in the heating need. Also, your plants will need less water because the canopy won't dry out as fast. That's a minor thing, but it can mess with your feeding schedule if you don't adjust.
Blurple LEDs are a harder case. Older blurple fixtures (like the ones from 2019-2021) often have lower efficacy than even a modern HPS system. If you have a 600W blurple that's 3 years old, it's probably pulling 600W from the wall but only putting out 600-700 PPF. A modern ViparSpectra 1200w led grow light (like the PAR 1200) pulls 260W but puts out 700+ PPF. So you're getting more light for less than half the power. In that scenario, the retrofit pays for itself in 2-3 grow cycles.
But if your blurple lights are less than 2 years old and still under warranty? I'd run them until they die or the warranty expires, then replace. The environmental cost of trashing a working fixture isn't worth the minor energy savings.
Scenario C: Expanding on a Tight Budget
This is where the cost controller in me really gets to work. You want to add another 4x4 tent to your operation, but you only have $200. What do you do?
Here's what I did: I bought a used 600W HPS system from a local grower for $60. It works perfectly fine. It's not as efficient as a $300 ViparSpectra full spectrum LED, but I have $200 left over to buy better genetics or upgrade my ventilation. That's a better ROI in the short term.
The argument for buying new LEDs is strong, but only if you have the capital. If you're bootstrapping, go with whatever works. A 600W HPS will still grow great plants. It's just more expensive to run. But if I'm switching out lights every 6 months because I'm upgrading, I'm just wasting money on depreciation. Use the used gear until you can afford to replace it with a quality LED like a ViparSpectra.
One more thing: don't be tempted by ultra cheap LEDs on Amazon that claim 1000W but draw 100W. They're not efficient and they won't last. A used HPS from a reputable brand is better than a new no-name blurple. But a used ViparSpectra? That's the jackpot. Check local classifieds. People upgrade all the time and sell their old gear for cheap.
How to Know Which Scenario You're In
Honestly, ask yourself three questions:
- What's the lifespan on my current gear? If it's less than a year old, wait. If it's breaking down, replace.
- What's my electricity rate? Calculate your cost per kWh. If it's above $0.15, the math for LEDs gets better faster.
- What's my capital availability? Do I have $300 per light, or do I need to scrape together $200 for the whole tent?
There's no magic formula. But if you're in Scenario B (retrofitting) and you're on a high electric rate, the upgrade pays for itself in 12-24 months. If you're in Scenario C and don't have the cash, a used HPS is fine.
Pricing as of January 2025. Verify current rates. Always calculate total cost of ownership, not just the sticker price.