LED Lighting for orchidbox

Events highest quality LED isn't 4-5x more efficient than fluorescent light. Many cheap ones are slightly better than fluorescent light, and some of those LED strips which you cut them into lengths are less efficient than fluorescent light.

If your light fixture has to be inside the box, it makes a difference to invest on a good quality LEDs. This is part of the reason I've been going for the best efficiency LEDs (within reasonable cost).

The amount of lumen you'll need depends on how big your space is.

The spectra are very different between fluorescent vs white LEDs, but if you don't nit-pick, you can think PPF/lumen or PPFD/fc is somewhat similar. For example, I calculated PPFD/fc from Cree data sheet, and they are 0.15-0.18 (depending on K and CRI). From my measurement, T8 and T5HO gives about 0.14-0.16.

 

Insulation between boxes? A sheet of 1/2" or 3/4" sytrofoam insulation board might help there. You can also run a fan across your lights to bring outside air in for cooling if they're separated from the environments.

 

What kinds of orchids are you targeting? 2000fc of continuous light is very strong for most orchids. You can grow many carnivorous plants with that much. Under the perfect light distribution with no waste, you do need 30000 lumen to cover 15 sqft (1 fc = 1 lumen/sqft) at 2000fc.

With 5'x3' area, you are right 7000lumen is a bit low end (unless there is no light loss due to reflection etc). But 10000-20000 lumen is probably good amount.

If you are handy, samsung H-series is amazing (almost 190lm/W). High efficiency means low heat production. It is supposed to be available any time now, and I'm waiting for mine:

Samsung LT-HB22D 1120x18mm, 4000K, 4040lm, 187lm/W, 22.5V, 960mA, 21.6W, SI-B8T221B2HUS, $34.29 from digikey http://www.digikey.com/product-search/en?keywords=B8T221B2HUS

1 of this (21.6W) produces similar amount of light as 54W T5HO. 3-4 of these will be perfect for your space. It is a little pricey, though. Samsung inFlux is less efficient (=more heat), but about a half price of H-series.

 

Cymbidium goeringii is not a cold grower at all. While it can certainly tolerate lower temperatures in winter, I find that they do best when grown reasonably warm - nights no lower than 65°F.

 

Yes, COB or array LEDs are much easier than individual LEDs. I think that individual LEDs are quite a bit more expensive if you are not reflowing them by yourself, right?

If you need dimming, 1x Mean Well LPF-90D-48 matches well with 4x LT-HB-22D
http://www.meanwell.com/webapp/product/search.aspx?prod=LPF-90D&mws=84A71A9516C6A789
1.88A with 48V max. So you can connect 2 units in parallel and connect these two in serial. If you don't need to dim, you can get cheaper drivers, I think.

I'm going to see if I can use aluminum C-channel. Basically it is similar to what I did with Phillips XF-3535L (link here). If you want to go with something better, something like this may be better:
http://www.heatsinkusa.com/1-000/

I haven't decided if I mount it with screws or the thermal glue. But I did order FUJIK Silicone Thermal Adhesive. Thermal paste + screw generally gives better heat conduction than thermal adhesive, but adhesive might be good enough. If adhesive is good enough, then it is almost as easy as XF-3535L.

 

Your enclosure looks very nice! What paint did you use inside? I've been using elastomeric paint (used for roof painting) for the last couple years, but I started to see some peeling problems around the area with continuous contact to water.

 

That's 15C, right? That's not really cold. A cold grower, in my book, would take nighttime temperatures of 7-10C. I just checked, and Jay's site calls it "cool" at 15C...

FWIW, I find the Asian cymbs do really well in semi-hydroponic culture. Lots of air to the roots, but always lots of moisture, too.

 

It was probably smarter to use melamine instead of glass. It is better to have reflective surface, so you can reduce the light loss. When I use aquarium for orchids, I surround it by aluminum foil or paper. I think the outer coat of melamine is some kind of plastic, so it probably works well.

I've never done individual LEDs, other people use oven or hot air gun etc. But I personally think that it is not worth using individual LEDs although I haven't done the cost calculation recently.

If you can find an appropriate driver, serial driving is probably more robust. But the total forward voltage becomes higher (meaning that you might need more expensive wires). With the Samsung strip, you can mix different K. They use mostly same blue diodes, and the difference in color temp is mainly from the phosphor.

 

Surface mount components (including ball-grid array components) are attached by placing the components on boards with solder already applied to the board, and running through a bake oven, which causes the solder to flow. You just want to keep the oven a little above the melting point of the solder.