Spectrum king and Nextlight are about the best performing and efficient grow lights on the market at the moment. The reason for their high cost, is because unlike other cheap LED manufacturers (looking at you china). They actually design lights that can compete with traditional gas discharge technology. Its a sad fact that most LED light fixtures on the market, are infact inferrior to gas discharge lights.
When designing and manufacturing LED light fixtures, the efficiency of the light is mostly dictated by the toplogy, not the model or type of LED chips used. Typically to build a fixture with higher efficiency, requires more diodes and circuit complexity to acheive this. This adds more cost and makes it harder to convince consumers to invest. This is why there are many cheap fixtures on the market. But yet underperform in comparison.
When looking at the long term investment, i must point out to people that choosing the higher quality but yet more expensive product is going to be more economical over the years. The savings from efficiency and higher performance ends up paying itself back much more than the cheaper fixtures. You typically also get longer life and better warranty as well.
Just some further information on competing light technologies.
With LED's like i have explained, the topology and design has a much more significant impact on fixture efficiency than the choice of the diode chips themselves. Saying that, there is a misconception that
COB is more efficient than typical SMD chips. This is not the case however. Although efficiency is improved from its substrate dicharge of heat. It is heavily counteracted by the concentration of heat created from the higher proximity between the diodes. This effects the total efficiency as temperature is directly related to a diodes radiant efficiency.
As has always been the case, manufacturers are always trying to find ways to sell more products. Just recently there has been a surge in popularity of Ceramic Metal Halide. But again more misconceptions cloud the technology.
CMH is not a new technology, its been around for oh, nearly 30 years. Philips introduced a new design back in 2011 called CDM Elite Agro for the growing industry after seing more interest from indoor horticulture (same bulb used today). This new product was an improved design from previous ceramic metal halides. Attributed with higher efficiency and better spectrum uniformity (I would recommended current CMH users stick with the philips bulbs only).
However, there is no current
evidence that shows CMH as being superior in efficiency or efficacy (read up the differences because its most important). Current
papers that have looked at technologies and put them through rigorous testing systems such as integrating spheres. Have come to all but similar conclusions. Showing that the efficiency lags just behind traditional single ended HPS but is left behind by double ended HPS.
Although one can argue about the spectrum quality, as far as plant biology science is concerned. Light quality is far less important than light qauntity. Saying that, if we were to go by the old aged mccree curve. CMH would loose that arguement based on the principle that quantum yield (photosynthetic efficiency) is higher in the red part of the spectrum, where HPS has more affinity with.
If i had a chance to redo my light system, i would stick with gas discharge lights or invest in the expensive but long term economical LED fixtures such as spectrum king or nextlight.