LED vs HPS: Cost Savings Explained🌱💡

If you’ve been in the grow game a while, chances are you’ve run an HPS grow light. They were the industry standard for decades. But now, the LED grow light revolution has taken over, and for good reason: they save you money while still smashing yields.

This 10-minute guide breaks down the numbers, hidden costs, and real savings when you switch from HPS to LED.

If you’ve been growing for a while, you’ve probably run an HPS grow light. It works, it’s cheap to buy, and it throws heat like a space heater. Modern LED grow lights flip that script: higher efficiency, cooler tents, and long-term savings. In this guide, we’ll break down the real numbers—energy, heat, replacement costs—and show where LEDs save cash in a typical grow tent kit. It’s a fun, no-nonsense read from your favourite hydroponics store (hello from The Hydro Bros 👋).

TL;DR — Where the Savings Come From

• Lower watts for the same PPFD: A quality LED grow light can match a 600W HPS output at ~480–650W depending on model and efficiency.
• Less heat, less HVAC: You’ll run your inline fan slower and your AC less often.
• No bulb swaps: LEDs last for years; HPS lamps need regular replacements to keep yields consistent.
• Better grams per watt: More output for the same electricity means lower cost per gram.

Bottom line: HPS is cheaper upfront; LED is cheaper to own. Over a few cycles, LEDs usually pay for themselves.

How LED and HPS Differ

Power Usage & Monthly Bills

Example: 1.2 m x 1.2 m tent. We’ll compare a 600W HPS vs an efficient 480W LED covering the same area. Electricity price assumed at £0.30/kWh. Adjust the maths for your tariff.

Note: Many top-end LEDs draw 600–650W to outperform a 600W HPS—still more efficient per photon, but your exact energy saving depends on the fixture you choose.

Heat & HVAC Costs (The Hidden Bill)

Heat is the silent budget killer. Every watt becomes heat in your tent. Roughly, 1 W ≈ 3.41 BTU/h.

In real terms, many growers see an extra ~200 W average HVAC draw (fans/AC) when using HPS vs LED in this tent size. Over a 12-week cycle (1,176 h), that’s ~235.2 kWh—about £70.56 at £0.30/kWh—saved with LED.

Bulbs, Lifespan & Maintenance

• HPS grow light: Lamps lose output quickly; many growers replace every 2–3 cycles to hold yields. Add reflector wear and the odd ballast issue.
• LED grow light: Quality fixtures run for years. No bulb swaps, just keep diodes/heat sinks clean and ensure good airflow.

Yield & Efficiency (µmol/J & g/W)

Modern LEDs push high efficacy (µmol/J), delivering more photons to the canopy for the same electricity. Practically, that often translates to more grams per watt. Exact results depend on genetics, environment, and hydroponic nutrients, but LEDs generally let you run higher PPFD with better canopy uniformity—especially in scrogged tents.

12-Week Cycle: Total Cost of Ownership (Example)

Assumptions: 4 weeks veg @ 18 h/day, 8 weeks bloom @ 12 h/day, electricity at £0.30/kWh.

Optional HPS lamp cost: If you budget ~£30 per lamp every 2–3 cycles, that’s ~£10–£15 per cycle more for HPS.

Break-Even & ROI

Example kit pricing (illustrative): an HPS kit ~£150; a quality LED ~£650. Difference: £500.

• Per-cycle saving (from above): ~£113 (energy + HVAC).
• Break-even: £500 / £113 ≈ ~4.4 cycles (about a year if you run back-to-back).

Faster break-even if your electricity is pricier, your room runs hotter on HPS, or you replace bulbs more often. Slower if your LED draws closer to HPS wattage or you grow in a cool space with minimal HVAC.

How to Pick the Right LED (What Actually Matters)

• PPF & efficacy (µmol/J): Higher = more photons per watt. Look for trusted diode/driver brands.
• Footprint & bars: Batwing/bar LEDs give even canopy coverage in 1.2–1.5 m tents.
• Dimming & control: Handy for dialing PPFD, sunrise/sunset, and pairing with smart controllers.
• Ingress rating & build: IP-rated fixtures play nicer with humid environments.
• Warranty & support: Buy from a grow store that actually answers the phone.

Ready to upgrade? Check our hand-picked LED grow lights. If you’re starting from scratch, our grow tent kits bundle lighting, extraction and essentials so you can plug in and grow.

Setup Tips When Swapping HPS → LED

• Hanging height: Start higher than HPS and lower gradually while watching leaf response.
• PPFD, not watts: Use a PAR map or meter if possible; aim for even canopy coverage.
• VPD & airflow: LEDs run cooler; you may be able to raise temps slightly and reduce fan speed.
• Nutrients & irrigation: Stable environment = consistent uptake—pair with quality hydroponic nutrients and steady irrigation.

LED vs HPS — FAQs

Are LED grow lights cheaper to run than HPS?
Usually yes. You’ll save on electricity (fewer watts for similar PPFD), plus reduced HVAC and no bulb swaps.

Do LEDs yield more?
With the same PPFD and dialled-in environment, LEDs often deliver better grams per watt thanks to higher efficacy and more even spread.

Will LEDs work in my existing tent?
Absolutely. Choose the right wattage for your footprint, hang correctly, and you’re good. Need help sizing? Ping us—we’re a friendly grow shop that actually grows.

Next Steps

Want personalised advice from a real human? Chat to The Hydro Bros. We’ll help you pick the right LED grow light, size your inline fan, and choose the best hydroponic nutrients for your setup. That’s what a proper grow store is for.

Browse LED Grow Lights →