HPS (High Pressure Sodium) and LED are the two dominant lighting technologies for indoor growing. Both produce excellent results in the right conditions — but they suit different growers, budgets, and setups. This guide compares them directly across the factors that matter most: yield, running cost, heat management, and setup simplicity.
HPS vs LED: Head-to-Head Comparison
| Factor | HPS | LED | Winner |
|---|---|---|---|
| Upfront cost | £150–£350 for ballast, bulb, and reflector | £300–£700 for a quality unit | HPS |
| Running cost (600W equivalent) | ~600W actual draw | ~400–465W actual draw | LED |
| Heat output | High — typically requires air-cooled hood or extra extraction | Low to moderate — easier to manage | LED |
| Yield per watt | Comparable at equivalent PPFD | Comparable at equivalent PPFD | Draw |
| Lifespan | 10,000–24,000 hours (bulb replacement needed) | 50,000–100,000 hours | LED |
| Setup complexity | Requires ballast, reflector, bulb, and cooling | Single unit, plug and play | LED |
| Spectrum control | Fixed spectrum — separate MH bulb for veg | Full spectrum throughout, some models dimmable | LED |
Yield: Does HPS or LED Produce More?
At equivalent PPFD levels, modern LED and HPS produce comparable yields. The key word is equivalent — a 600W HPS running at full power delivers more raw photons than a 300W LED, but less than a 465W LED of equivalent quality. When comparing lights at the same intensity level (same PPFD at canopy), controlled grows consistently show similar yields from both technologies. LED does not inherently out-yield HPS; it produces the same yields at lower wattage.
Running Costs: How Much Does HPS vs LED Cost to Run in the UK?
At an average UK electricity rate of 24p/kWh, running a 600W HPS for 12 hours per day costs approximately £630 per year. Running a 465W LED for the same duration costs approximately £490 per year — a saving of around £140 annually. Over a 3-year growing period, that saving (£420) largely offsets the additional upfront cost of a premium LED over an HPS setup.
Heat: The Practical Advantage of LED
HPS lights convert a significant portion of their energy into infrared heat, which radiates directly from the lamp. In a sealed or poorly ventilated grow space, this can push temperatures above the 28°C upper limit for productive growing — particularly in summer or in warm rooms. LED produces less radiant heat, making temperature management significantly easier. For growers in warm climates, small grow spaces, or summer growing, LED’s lower heat output is a meaningful practical advantage beyond just electricity savings.
When HPS Still Makes Sense
HPS remains a valid choice in specific situations: when upfront budget is tight and a used or budget HPS setup costs significantly less than a quality LED; in cold grow spaces where the heat output from HPS is beneficial rather than problematic; and for growers who have an existing HPS setup in good working order and are not yet ready to replace it. HPS is a proven, reliable technology — it simply costs more to run over time than equivalent LED.
Frequently Asked Questions
Frequently Asked Questions
For most UK growers in 2026, yes — modern LED produces equivalent yields at 20–30% lower electricity consumption and with less heat to manage. The higher upfront cost of quality LED is typically recovered within 1–2 years through electricity savings. HPS remains valid in cold grow spaces, where its heat output is an advantage, or where budget constraints make the upfront LED investment impractical.
Yes, with one important check: verify the hanging height. LED lights are typically hung higher than HPS in the same space to achieve the correct PPFD at canopy — check your LED manufacturer’s recommended hanging distance rather than using the same position as your HPS. Extraction may also need adjusting, as LED produces less heat, which may change your ambient grow room temperature.
No — at equivalent PPFD levels, modern LED and HPS produce comparable yields. The persistent belief that HPS out-yields LED comes from early-generation LEDs that were far less powerful than their marketing suggested. A quality 465W LED delivering 900–1,000 µmol/m²/s at the canopy will produce yields comparable to a 600W HPS at the same intensity.
HPS bulbs typically last 10,000–24,000 hours before output degrades significantly — most growers replace them annually or every other season. Quality LED fixtures are rated for 50,000–100,000 hours, meaning no bulb replacements and minimal maintenance for 5–10 years of use.