Design a Grow Room Light:8x4feet, Led Strips or Solskins?

I get asked daily about the best way to light a room and the options today are more numerous than ever. As a starting point it is no longer unreasonable to begin from a place of efficiency and by that I mean umols/j, not lumens per watt. Your inputs in terms of power used for lighting relative to yield out is of course important, but the sidebar to this is that contemporary lights at high efficacy, also deliver excellent photon outcomes. So we are going to do a shoot out in Dialux that compares LED strips with SOLSKIN’s based on a minimum of 2.5umols/j and do this for a 4×8 foot space with a target of 1000 watts

Check out our most recent Video on how to use Dialux to design your grow room lighting

So its important to note here. Most data in the market place from Led grow light manufacturers is heavily focused on integrating sphere data. Some also provide data from Goniophotometer’s. The key point here is that only goniophotometer’s can produce IES files. These are files which very accurately map a lights output across typically 855 data points and on request you can get increased C plane testing to provide even more granularity. The point here is that you can believe or not, integrating sphere data as its just data on paper. Im not suggesting such data is incorrect or marketing spin, you have to come to you own conclusion. The point is that with IES files there is no where to hide, the data is the data and once you have you hands on it, well information is POWER. I wonder why all manufacturers dont provide this data to customers. Why try to build a light when you dont have all the facts?

So what we are going to run is data based on two scenarios. Links to the full report for both these will included at the bottom, we will also include links for the IES files so if you choose you can run these in Dialux(Free Software) to confirm or make your own designs.

1. Latest 220 LPW watt 2835 chips from Cree, yet to be commercially released but we are testing G Class on 560mm MCPCB, 3500K

2. SSK-272 Boards in Nichia H series, top bin available in 3500k with 16 pcs of latest Cree Deep Red.

Our goal is to run 1000 watts of light and try to provide the best coverage in an 8x4ft room. Typically 1000 watts might be considered a bit under for this size room. You can be the judge

SSK-1560-2835 Performance

 

Assumptions

Clearance height: 7.000 ft, this is the height of the lights,

Reflection factors: Ceiling 70.0%, Walls 90.0%, Floor 20.0%. These are standard reflective surface options in Dialux, with the exception of walls which we increased to 90% based on Mylar

”Mylar can be up to 97% reflective, and is available in thicknesses of 1 mm and 2 mm, and in smooth and textured finishes.”

https://www.maximumyield.com/shining-a-light-on-reflective-materials/2/1487

By way of explanation the work plane is the height level where the light is measured and for the sake of the design can be referred to as the top of the canopy

So in summary what we can see is we are slightly under our 1000 watt target, we are using 32 strips, that at 700ma each provides 30.5 watts. The height floor to canopy is 5.5 feet or 18 inches from the lights and we are at 2.7umols/j eff. This gives us a min PPFD of 599 and max 859, perhaps more important is the ratio of min to average which defines the spread, the higher this number the better the coverage. The min/max ratio refers to the delta between the centre hotspot and the lowest corner.

Driver Recommendations

HLG-480H-48A: Use two drivers to obtain 960 based watts, could be extended using the A driver features. 16 Boards in Parallel per driver

Tip: Use Offset Wiring, every 2nd two(across) boards wired to Driver 1, this provides redundancy in case of single driver failure. You will still retain half the light across the entire space. i.e. strip 1 and 17 on Driver one and 2 and 18 on Driver 2

So lets now look at the SSK-272 Board. The first assumptions remain the same

So, again in summary what we can see is we are slightly under our 1000 watt target, we are using 9 Solskin boards, that at 1.5a each provides 81 watts. The height floor to canopy is 5.5 feet or 18 inches from the lights and we are at 2.7umols/j eff. This gives us a min PPFD of 593 and max 877, the ratio of min to average which defines the spread is 0.76, the higher this number the better the coverage. The min/max ratio refers to the delta between the centre hotspot and the lowest corner.

Driver Recommendations

HLG-480H-54A: Again we would recommend the use two drivers to obtain 972 based watts, could be extended using the A driver features. 16 Boards in Parallel per driver, we would also suggest wiring in offset to build in redundancy.

Final Summary

So what is the takeaway from this, both have around the same power level, evenness across the canopy. Both have the same cost to drive them(2×480 watt drivers) and both have almost identical watts per square foot performance, so either solution would work. The issue in the end is really cost. The 12 up Solskin is going to be approximately twice the cost in pure hardware terms to purchase. Now in terms of total cost of ownership, building the strips is going to be more time consuming in terms of mounting and wiring etc, but if your into DIY and enjoy the build, then that cost is proportional to your love of the build. There is a hidden value in Solskin build and that is that it is being run in this scenario at 1.5amp and you have the option to power it to nearly 3 amps and get an average of a 1390 umols with a similar min/average delta if you wanted to run a monster flower room. You can off course overclock the power on strips, but the thermal challenges would make this a more difficult upgrade.

Two other aspects should be considered with regard to the choice. The strip build is more flexible with respect to canopy heights as the relative luminous structure allows for plants growing almost to the light with minimal impact to plant structure, conversely the tight diode layout on the Solskin boards will provide greater canopy penetration

PS. Please note if you watch the Dialux video you will note the suffix issues on PPFD IES files vs Lumen Files. I have corrected the first strip data with the proper suffixes but not the Skin data. The data however is in PPFD and umoles/j in case you picked up on this

4×8272 Full Report on SSK-272

4x82835all Full Report on SSK-1560-2835

IES file for SSK-1560-2835

IES file for SSK-272