How do I determine the lumen/watt ratio of led lights?

I'm expanding my operation, and would like to make the switch to a more efficient light-source. As far as I know, the L/W for LED lights varies enormously among different manufacturers. Could anyone recommend a good brand/s? Heat is a factor, but I'm primarily looking for LED systems that can outperform HID's at a similar price (including cost to run them). Thanks!

Cree has a very high lumen per Watt rating. So does the Golden Dragon Plus series of LED's. Most of the time you can check the manufacturer's spec sheet and see what their efficiency is.

Remember, though, lumens aren't the whole story. Spectral distribution is very important and plays just as large a role in the efficiency of the system. Your plants can only absorb light of a certain wavelength so much. By having the correct ratio of light you can increase lumen uptake of the plant across the entire PAR spectrum. This is often referred to as PUR (photosynthetically useable radiation).

Lumens are useless for plants...Par light output in umols show the true growing power of any light source. This is specially true for LED's because of their wavelength specificity...which is where "pur" comes in.

Apache Tech AT120 have great par umols/watt. Over 1000umols @12". They use cree diodes and are made to last. Operating temps is less 85*. And they are a bay area company too.

I use Apache so I can only talk about them,

Apache's only cover a 2.5'x3' area for flower, but 2 AT's are equal or better than 1000w hps and can give you a little better spread too.

2 AT120's would be 314w running power on 12/12 for 30days @ $0.25/KwH = $28.26/month...$339.12/year

1000w HPS system is 1100w running power on 12/12 for 30days @ $0.25/KwH = $99/month...$1,188/year...not including cooling cost and bulb replacements.

That's 848.88 a year in lighting electricity alone. It would be a $1800 investment for the AT's so about 2 year payback if only judged only on lighting electricity savings. After one harvest you're payed back really though

The bigger the operation the bigger the savings.

Growers House has the run down of PAR measurements for a few lights on their website. I think it's in their blog.