Small build for succulents

[ukstripbuilder]

Hi ledgardener community! I'm looking for a bit of a sanity check on a small veg-like strips build for my succulents. Very happy to be told there are better options so please shout if that's the case!

Anecdotally the advice seems to be to use lighting with a CCT of 6500K, although I've been unable to find any academic material to back this up. I presume the blue bias is to prevent stretching/etiolation which is common with succulents. As 6500K strips seem to be hard to acquire in the UK, I'll be going with the nearest available CCT of 5000K.

I'm happy to pay a bit more for the build to get something efficient and I also want to run the strips relatively softly to avoid having to buy serious heatsinks which add to the cost faster than just adding more strips. I'm looking at the EB Gen 3 Slim strips, available from Digi-Key - https://www.digikey.co.uk/product-detai ... =367115794

Requirements:

• Dimensions to light: 60cm x 64cm = ~0.4m^2.
• Spectrum: 5000K @ 80 CRI
• Target PPFD: 350/400(source: https://herebutnot.com/light-recommenda ... useplants/)
• Dimming support via Pot/PWM
• "1ft" strips - I'm looking at the 340mm ("1ft") strips to give me the freedom to change the shape of the array later if I desire.
• Voltage under 60V SELV limit
• Minimal (aluminium angle mount) heatsinking

Nice to haves:

• Ability to add more strips

Trying to roughly follow @PeteR_1's usual template:

@ 10.9V / 700mA / 1530 lm / 200lm/W

60 * 64 = 3840 / 10000 = 0.38 m2 (~ 0.38 sq m). Rounded up = 0.4m2
0.4 m2 * 400 (PPFD per sq m; High-Light Houseplants (Tropical Succulents like Christmas Cactus, Philodendrons, Monstera)) = 160 PPF (per 0.4 sq m)

For Bridgelux I use the Generic Conversion Factors... viewtopic.php?f=15&t=5756


Generic for White PC LEDS - Lumens to PPF (PPF/Lm) Factor (cF):
0.014 = 5000K 80 CRI Cool
0.015 = 4000K 80 CRI Neutral
0.016 = 3000K 80 CRI Warm

200 Lm/W * 0.014 = 2.8 PPE

160 PPF / 2.8 PPE = 58 Watts

1530 Lm * 0.014 PPF/Lm (cF) = ~21.4 PPF per Strip
160 PPF / ~ 21.4 PPF per Strip = 7.5 (~ 8) Total Strips

To get to the 10 unit price break on Digi-Key I can run an additional two strips and run all the strips at a softer 500mW for the same PPFD.

@10.63V / 500mW / 1147lm / 215lm/W

215 Lm/W * 0.014 = 3.01 PPE
160 PPF / 3.01 PPE = 54 Watts

1147 Lm * 0.014 PPF/Lm (cF) = ~16 PPF per Strip
160 PPF / ~ 16 PPF per Strip = 10 Total Strips

Wired 2S / 5P: 21.36V / 2500mA

For a driver I think this is what I need - HLG-120H-24AB. The 100W AB version wasn't available anywhere, hence going for the larger 120W.

• Max power = 120W
• Constant current region: 12 -24V
• Current adjustable range 2.5A - 5A
• 10 -> 100% dimming
• Efficiency @ 53.4W / 44.5% load = 91%

I would run this with both inbuilt pots (VO/IO) set to minimum (22V/2.5A) to achieve 21.36V/2500mA in the constant current mode of the driver then use the external pot to dim further if necessary. Is this OK for 2S/5P?

I'd also appreciate if anyone has a recommended UK source for the aluminium angles?

Thanks!

[PeteR_1]

Hello @ukstripbuilder,

Welcome to the forum community.

The numbers / calculation look good...

• The 5000K LED strips are OK, ~ 22% Blue wavelengths. 90 CRI may provide more Red and Far Red wavelengths than 80 CRI, if desired. The 90 CRI BXEB Gen3 also usually provides more Blue wavelengths, but there is little info on their %SPD.

• The 120 Watt LED Driver is OK. 2-Series/5-Parallel circuit Is 76 Watts and 21.8 Vf at Test current. The Vo pot on the LED driver should not be touched, only adjust the Io pot. Vo pot adjusts the “maximum” Volt, e.g., using 25 Vf strips with that Driver. The HLG and XLG Series drivers at factory settings will automatically adjust the output voltage when operating within their CC region.

You’re welcome and good luck.

BTW thanks for sharing the link...

[ukstripbuilder]

Thanks for fast feedback @PeteR_1!

The 5000K LED strips are OK, ~ 22% Blue wavelengths. 90 CRI may provide more Red and Far Red wavelengths than 80 CRI, if desired. The 90 CRI BXEB Gen3 also usually provides more Blue wavelengths, but there is little info on their %SPD.

I'd consider the 90 CRI strips if I were able to source them anywhere. Unfortunately I couldn't find anywhere selling them to the UK.

Are there any other better strip choices for spectrum at a similar level of efficiency and price?

[wuwuorganics]

No expert here, but maybe you could check these strips out. 3500k 80cri lm561c diodes, so not the newest and most efficient diodes out, but still pretty efficient it seems especially for the price. Not sure on what the 10 strips would cost you for the bridgelux strips, but you could grab just enough of these to get the free shipping and probably save money/have extras for future builds and to play around with. Only 48 diodes per strip, but maybe that would pair well with the succelents as they don't require as much light as other plants it seems. Just my two cents on another possibility.

https://www.arrow.com/en/products/si-b8 ... 8U11156HUS

[greengenes]

I second the 90cri recommendation if possible fo you. The higher cri SPD does give a great veg and health response.

5000K is good. If anything is maximizing out the needed blue % of any species. 20+% of the SPD to the blue is a lot of blue. Especially if not balanced out on the other end in the red.

For a driver, you're really under utilizing what you linked and making it more complicated than it needs to be with the AB version. Better off getting something close to the wattage your end system will be. They have an HLG60-24 to keep it inline with the original thought, or can find other options if you dig into it.

[ukstripbuilder]

I second the 90cri recommendation if possible fo you. The higher cri SPD does give a great veg and health response.

Unfortunately I just can't get hold of the 90 CRI strips here in the UK. The closest available option is the Thrive strips at 98 CRI but the efficiency hit is pretty high (145 lm/W at test current (350mA) vs 200 lm/W for the regular gen 3 slim CRI 80), and they're 23% more expensive. Is the improved spectrum really worth the additional cost in both outlay and electricity?

For a driver, you're really under utilizing what you linked and making it more complicated than it needs to be with the AB version. Better off getting something close to the wattage your end system will be. They have an HLG60-24 to keep it inline with the original thought, or can find other options if you dig into it.

Agreed I'd only be hitting 44.5% load on the 120W driver but this still equates to 91% efficiency, matching that of the 60W driver. I realise I'd need to run the driver in constant current mode, but sizing it a bit larger allows for easy later expansion by just adding additional 2S parallel legs. The 120W driver is only £10 more expensive than the 60W so it seemed to make sense.

[wuwuorganics]

https://www.digikey.co.uk/products/en?k ... C14C039ALL

Here are some 5k 90cri strips. Never saw/heard of anyone using the seoul strips, but maybe worth a look.

[PeteR_1]

I'd consider the 90 CRI strips if I were able to source them anywhere. Unfortunately I couldn't find anywhere selling them to the UK.
Are there any other better strip choices for spectrum at a similar level of efficiency and price?

Vesta Gen2 2700K and 5000K 90CRI, 560mm... https://www.digikey.co.uk/product-detai ... ND/7899252
Vesta Gen2 2700K and 5000K 90CRI, 280mm...https://www.digikey.co.uk/product-detai ... ND/7899251
160 PPF / 2.2 PPE = 72.8 Watts


These can provide two separate channels;
3192 Lm (max at 25 watts 2.2 PPE @ 560mm) supplemental 90 CRI 2700K for added Red and FarRed, or
3352 Lm (max at 25 watts 2.2 PPE @ 560mm) supplemental 90 CRI 5000K for added Blue, Red and FarRed
3272 Lm (max at 25 Watts 2.2 PPE @ 560mm) supplemental 90CRI 3900K ... 12.5 Watts each channel, 1:1 ratio


LED Strip Comparisons with Vesta Gen2 TL-2750G at varying ratios

Edit:
Or Samsung L2 Horticultural Strips 560mm... https://www.digikey.co.uk/product-detai ... ND/9952090
The Samsung L2 Horticultural Strips 280mm... https://www.digikey.co.uk/product-detai ... D/10284209
160 PPF / 2.7 PPE = 59.3 Watts

https://grow.arden.lighting/kit-emerald-hammer-eh500k/

[ukstripbuilder]

Thanks both for the suggestions.

https://www.digikey.co.uk/products/en?k ... C14C039ALL

Here are some 5k 90cri strips. Never saw/heard of anyone using the seoul strips, but maybe worth a look.

I think I'm keen to stick to the more commonly used brands for now.

Vesta Gen2 2700K and 5000K 90CRI... https://www.digikey.co.uk/product-detai ... ND/7899252

Interesting suggestion. A few concerns though:

• For my use case where I'm aiming for a spectrum with a CCT around 5000K (high blue%) I imagine I wouldn't really be using the 2700K channel? If I was to use it, I'd be moving more towards a CCT of ~3700K, essentially using watts for an increased red % I didn't originally aim for?
  
  I think I found a @TEKNIK report on rollitup showing the spectrum for both channels run 1:1:

  

• The efficiency is pretty bad on these gen 2 LEDs - the 5000K channel is 135lm/W and the 2700K channel 129lm/W (both at test currents. Those efficiency levels are pretty close to the (gen 3) Thrive strips (138lm/W) which would up the CRI to 98.
• With around ~12.5W per channel @ 500mA (test current) I'm guessing I would need some pretty serious heatsinks should both channels be run concurrently (25W).

[followup after your edit]

Or Samsung L2 Horticultural Strips 560mm... https://www.digikey.co.uk/product-detai ... ND/9952090
The Samsung L2 Horticultural Strips 280mm... https://www.digikey.co.uk/product-detai ... D/10284209
160 PPF / 2.7 PPE = 59.3 Watts

Also interesting, I hadn't seen these before. Pretty close PPE to that of the 80 CRI EB Gen 3 slims at 700mA.

Concerns for these:

• I'd only need 3 of the 280mm strips to reach my target PPF (also underdriven). I'm guessing this would impact the uniformity in the grow area?
• The strips are about 58% more expensive for the same PPF. Although some of this would be cancelled out by savings on the aluminium angle.
• At 25.8W typ, again I imagine that I'd need more serious heatsinks than the 3/4"x3/4"x1/8" angle I was considering using?

[PeteR_1]

Thanks both for the suggestions...

Interesting suggestion. A few concerns though:

• For my use case where I'm aiming for a spectrum with a CCT around 5000K (high blue%) I imagine I wouldn't really be using the 2700K channel? If I was to use it, I'd be moving more towards a CCT of ~3700K, essentially using watts for an increased red % I didn't originally aim for?
  
  I think I found a @TEKNIK report on rollitup showing the spectrum for both channels run 1:1:
  BRIDGELUX VESTA BOTH CHANNELS PARALEL CRI90 560MM WHITE 1AMP.png
• The efficiency is pretty bad on these gen 2 LEDs - the 5000K channel is 135lm/W and the 2700K channel 129lm/W (both at test currents. Those efficiency levels are pretty close to the (gen 3) Thrive strips (138lm/W) which would up the CRI to 98.
• With around ~12.5W per channel @ 500mA (test current) I'm guessing I would need some pretty serious heatsinks should both channels be run concurrently (25W).

[followup after your edit]
Also interesting, I hadn't seen these before. Pretty close PPE to that of the 80 CRI EB Gen 3 slims at 700mA.

Concerns for these:

• I'd only need 3 of the 280mm strips to reach my target PPF (also underdriven). I'm guessing this would impact the uniformity in the grow area?
• The strips are about 58% more expensive for the same PPF. Although some of this would be cancelled out by savings on the aluminium angle.
• At 25.8W typ, again I imagine that I'd need more serious heatsinks than the 3/4"x3/4"x1/8" angle I was considering using?

Yes, you would only require the Vesta 5000K channel at 500 mA max for 280mm strip @ 12.5 Watts (1000 mA max for 560mm strip @ 25 Watts) with minimal heat sinks, they will be operating at 50% max rated Amps (max rated 1.0 Amp for 260mm, 2.0 Amps for 560mm Strips)...

Can’t view the graphics at the linked site but your graphic shows overdriven LEDs that would require heavy duty heat sinks (or burnout), the max rating is 50 Watts @ 25 Vf, the graphic shows running at over 68 Watts...

The 280mm Samsung L2 would require 4 Strips running Below ~ 800 mA @ 17.2 Watts max each, 50% of Max rated Amps (max rated 1.6 Amps) with minimal heat sinks...

The difference between these strips and the 80 CRI strips are the increased percentage of Red and decreased Green wavelengths in the spectra.

The 90 CRI also has a higher percentage of FarRed which is not reflected in the PPE, but creates the “Emerson Effect” which increases photosynthesis, just like simply increasing the PPFD or total PPF.