LED grow lights are now the go to option for most weed growers cultivating in indoor spaces.Their USP is increased energy efficiency and better control over the grow room light cycle. However, with some simple tweaks you can improve your grow room LED performance to increase weed yield. Our friends at Grow Lights Australia provide some useful tips.
Improve grow room LED performance - check your driver
All LEDs require a power source, and that power source is called a driver, but drivers also vary in efficiency. When you add the LED driver efficiency to the equation you get the total system efficiency.
System efficiency is the "true" efficiency of running the grow light, so LED driver efficiency is also important. LED system efficiency in umol/j will always be at least 5% less than LED efficiency in umol/j because the best drivers are around 95% efficient. Efficiency is also lost through wiring and connectors in the form of voltage drop.
LED lights lose efficiency as you put more current through them – so the softer you run your LEDs (the less power you put through them), the more efficient they are. But LED drivers increase efficiency as you put more power through them!
Solution: Ensure that the driver matches the LED fixture. You want the driver to be running near its maximum rated power while the LEDs are running at around 1/3 of their maximum rated power.
Check the efficiency of LEDs
Many grow light companies quote system efficiency at their lowest setting, which looks good on paper but is less impressive in the grow room once you turn the LEDs up to the correct power.
You need to look at your grow room set up and check the LED system efficiency ie is your light set at the power level you intend to run it. This is tricky, but look at the system efficiency of your grow light at different currents to determine which is the most efficient.
Does dimming LEDS cause drivers to lose efficiency?
Dimming LED lights up and down can cause an efficiency issue ie you want the most efficiency from your driver, but when you dim your lights down (during veg etc) you will lose efficiency. Don’t worry too much about this.
Most LED drivers only start to lose significant efficiency when they’re dimmed below 70%. As mentioned before, the decrease in driver efficiency is offset by the increase in LED efficiency. In fact, at 50% power you may only lose a few percentage points of efficiency from the driver, but you may gain up to 5-10% efficiency from the LEDs, so you are still ahead!
The most important thing is to use an LED grow light with an efficient driver to begin with. While the best LED drivers have efficiencies of 95-96%, some cheaper drivers are only 85-90% efficient (or less).
Heat issues with LEDs
Heat is another area where LED efficiency is lost. Many growers are now replacing their HIDs with LEDs to reduce heat in the grow room, which is a good start. But keeping LED grow lights cool can also maintain, and even increase their efficiency, as they will lose efficiency as they heat up. One solution is to aim a fan at your light so that it cools the fixture at the same time as it is moving air around the grow room.
Many quality LED grow lights are passively cooled, which means they do not have their own fans. This may sound contrary: if an LED fixture has a built-in fan, surely that’s good for efficiency? The short answer is yes… but no!
LEDs that require cooling fans instead of passive heatsinking (cooling) make a lot of noise. The fans can also be prone to failure. Indeed, the life of a fan is much lower than the life of an individual LED which may have a usable life of 50,000 hours (11 years of 12-hour use a day).
More importantly, cooling fans are usually a sign of poor LED design, because it means the LEDs are too powerful or packed in too tightly, which means they do not spread light (and heat) as well as other lights.
On-board cooling fans also use power, which reduces the overall efficiency of the LED grow light. If you already have a fan in your grow room to strengthen stems and prevent mold, you might as well use it to cool your LEDs!
Use the LED driver to aid temperature control
In winter, having a driver in the grow room will bring a little bit of much needed warmth. The trick is to place the driver near the intake vent so that it warms the incoming air for the plants and not the LEDs. However, in summer temperatures, it’s a different story.
During summer, especially in Mediteranean regions where indoor grow temperatures rocket, it can be a good option to locate the driver outside the tent. While there may also be a small amount of voltage drop due to the longer power cable offsetting some of the efficiency gains.Nevertheless, cooling the room will also reduce the need for more air conditioning in summer, so overall the option is a good one.
LED efficiency tips to increase weed yield
- Look for a "true" full spectrum grow light to give you better results.
- Look for the best system efficiency.
- Match the driver to the LEDs.
- It is better to have more LEDs running at a lower current than fewer LEDs running at a higher current.
- Match the grow light to the intended grow area.
- Consider placing your driver outside the grow area to reduce heat and air conditioning costs.
- Hot LEDs are less efficient, so ensure your grow light has GOOD heat sinking to dissipate heat.
- A good spectrum might have a lower system efficiency, but it will produce a higher yield and better quality product, which means more "bang for buck".
- If you use LEDs in winter and it is cold, try adding a CMH or HPS lamp in the grow room for added warmth and light – a much better idea than running a heater.
- And don’t forget to combine with grow techniques for improving your grow room yields.