This is not your normal 5' x 5' grid where you use a lumen meter. That can be somewhat helpful, but we're going to use testing done at UL and Light Laboratory Inc., which are independent 3rd party light laboratories that do not have an incentive to make one brand look better than another. These are the same laboratories that most LED manufacturers use to test when designing their lights.
Each test from these companies is not cheap. For all the testing that we're requesting, the bill can run up to about $1,500 per light. This was no cheap endeavor, but we wanted to create the most unbiased, comprehensive, and informative comparison review test on the web. Therefore we needed to be using the best equipment available to do our testing.
The other amazing thing about this test? It's never-ending. That's right, we're going to continually test lights and add the information to this page along with the PDF of results directly from the testing lab. We'll also include information in easy to digest tables and graphs below, along with definitions of the terms so you won't need to be a optical scientist to understand what's going on.
There is no one size fits all when it comes to LEDs. We hope this testing helps you choose the best light for you. Also, if you're going to purchase a LED grow light soon, please consider buying from GrowersHouse.com. We put a lot of time and money into this testing to help our customers make informed purchasing decisions. Being a customer helps support our mission of educating fellow growers.
To make it easier on our customer's wallets, we're also offering a 5% coupon good for any of the lights featured in the testing below: GHLED5. Not combinable with other sales or discounts.
Definitions of headings are below the table.
LED Efficiency in umol/Joule (400-700nm): Often stated as micromole per Joule -- or seen as umol/j or PPF/W--means for every joule of electrical energy (Joule = watt x second) a number of photon micromoles are produced. Most entry level LEDs are between 1.0 and 1.7 umol/j. Higher end LEDs are usually 2.0 umol/j. 400-700nm relates to the wavelengths of light in nanometers (nm). 400-700nm is the spectral range that plants use most efficiently to photosynthesize. This range is also offtenly referred to as the range of Photosynthetically Active Radiation (PAR).
Total PPF (400m-700nm): PPF is the abbreviation for "photosynthetic photon flux". It gives the information on the number of photons, which are emitted by a light source. Only photons in the wavelength range from 400nm to 700nm are considered. This is the so-called PAR (photosynthetic active radiation) and photons within these wavelengths contribute to photosynthesis. The unit of the PPF value is µmol/s (quantity of light particles emitted per second). Knowing the PPF value from different light sources allows an easy and objective comparison on the total light output which can in theory contribute to photosynthesis. Please note that the PPF does not consider the direction in which the light is emitted.
Luminous Efficacy (lm/W): A measure of how well a light source produces visible light. It is the ratio of luminous flux to power, measured in lumens per watt. Wavelengths of light outside of the visible spectrum are not included in this measure. The majority of the light plants use to photosynthesize are visible, but there are non-visible spectra that plants also use including ultraviolet and infrared.