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New LED fixtures from Philips with efficacies of 1.9 to 2.46 micromol per joule

Posted by bugbee on 18 Aug 2016 at 20:50 GMT

We recently completed testing of three new LED fixtures from Philips Lighting. These fixtures had the highest efficacy (efficiency) that we have measured to date. All models are Philips GPL Toplighting.

The results are as follows:
1) Philips Deep red/white far-red 175 watt; 1.94 ±0.07 umol per joule
2) Philips Deep-red/white medium blue 200 watt; 2.44 ±0.05 umol per joule
3) Philips Deep-red/blue medium blue 215 watt, 2.46 ±0.05 umol per joule

Although our test results indicate 85 to 95% of the efficacy that has been reported by the manufacturer, two of the three fixtures had a significantly higher efficacy than other fixtures we have tested over the past three years. The variation in efficacy shown above (±0.05) is the standard deviation among three replicate fixtures. One of the fixtures was also tested in an integrating sphere by A.J. Both at Rutgers and the efficacy was within 2% of the values for the same fixture at Utah State University. The best previous efficacy we have measured was 2.05 micromoles per joule (see comment below from 13 April). All of these values are an increase over the 1.7 micromoles per joule from the technologies available at the time this manuscript was written in 2014.

The higher efficacy of these fixtures does not automatically mean that they are the most cost effective plant lighting option, however. These fixtures sell for about $800 and are only 175 to 215 watts. This is still about 10 times the initial capital cost of HPS technology ($400 for a 1000 watt fixture).

Using the associated on line calculator (see the comment below from 7 July 2014), assuming $ 0.10 per kWh and equal capture of photons for all types of fixtures, the time to recover the initial capital investment is about 10 years if the fixtures are used 16 hours every day (indoor cultivation), and about 30 years if the fixtures are used an average of 5 hours a day 365 days a year (supplemental lighting in a greenhouse). By comparison, the 600-watt wattage fixture that we tested from Fluence Bioengineering (see comment below from 13 April) has a lower initial capital cost per photon of output. Although it has a lower efficacy, the payback time is similar to the Philips fixtures.

It is significant to note that both the Philips and the Fluence Bioengineering fixtures have a less focused output than many of the previous LED fixtures we have studied. This makes it more difficult to take advantage of the more narrow output of typical LED fixtures. As discussed in the article, if a user can take advantage of the more focused photon distribution from LED fixtures, the photon capture is increased and the payback time is reduced.

We are continuing to evaluate advances in technology as they become available.

Competing interests declared: Bruce Bugbee is a co-author of this article

RE: New LED fixtures from Philips with efficacies of 1.9 to 2.46 micromol per joule

bugbee replied to bugbee on 27 Aug 2016 at 14:36 GMT

Philips has recently indicated that they are now pricing these fixtures in the commercial market at around $450 per fixture. This is a significant decrease in cost from the $800 that these fixtures were priced at for the US market. This price change alters the payback economics in proportion to the decrease in cost.

No competing interests declared.