LED PAR vs CFL HPS sunlight PAR

I hear sunlight is around 2000 µmol photons m-2s-1 PAR. CFL and HPS have a similar full spectrum

I also hear plants need 500- 1000 µmol photons m-2s-1.

Since LED grow lights target the specific wavelengths where photosynthesis peaks, i assume plants would much need less than 500- 1000 µmol photons m-2s-1 with LED grow lights.
I guess with LED 200 to 500 µmol photons m-2s-1 should be good enough for great flowering

Any thoughts ? Is there any online resource or thread there I can find this information.

Just for clarity, "full spectrum" would be every wavelength possible , technically the correct expression would be "continuous spectrum" I suggest people stop saying 'full spectrum" as it breeds confusion. Every light source has a "spectral distribution" with "gaps or emission lines". In any event, whatever light emitting device you use it will have its own spectral distribution, how much energy is expended with each wavelength. Other than CFL and HPS both (obviously) having a spectral distribution graph, I see no other similarities.
http://imgur.com/35tdZiF
http://imgur.com/9TTUMhg
thats just two arbitrary distribution graphs for CFL/HPS, I am sure if you looked long enough you could find a few that are similar, but not as a rule.imho

As for PAR, it is a measure of relevancy to the plant. The higher the better. All that is really going on there is a bias against 500-600nm light as plants do not require much in that range for the purposes of photosynthesis. When dealing with the visible spectrum I find a LUX meter sufficient for comparison.

Ideally, you want to dump energy into wavelengths that the plant favours. Green for example is mostly reflected by plants, so it doesn't make sense to have your peak power output in that wavelength. I am not saying plants do not need or use green light only that it is less important to photosynthesis, hence the bias. For those who insist on using spectrums heavily weighted in the yellow and green range, just simply understand it is an inefficient use of electricity.

Your assumption above is incorrect, plants require photons/light at appropriate levels for peak performance, and PAR readings from one source to another should be comparable. What IS important is how efficiently your light source converts electricity into useable light for photosynthesis. LED does this better as they target specific wavelengths, wasting less energy in the lesser useful wavelengths. So if I had a side by side HPS/LED grow, I would expect to see the same numbers on a PAR meter for the same size grow space at canopy level. The only difference is the LED will use significantly less wattage to achieve the PAR rating desired.

Of course there are many variables, but its always about the efficient use of energy. I do a shitty job of explaining this, as I have done it a hundred times and I always seem to get the deer in the headlights look, lol. Hopefully I did a better job with this attempt.

makes sense.
PAR is PAR, whether from HPS or LED
I Think Plants need around 500 par of light and dont care if its from HPS or LED
BUT even within PAR range some wavelengths are more powerful like 660nm may be 430nm also. I guess LED will have more of 660nm and 430nm and the PAR value may be same as HPS. So LED may be more powerful, thus 400 par produced by LED can be as good as a 600 PAR by HPS

I still wonder how much PAR is needed in grow room

http://rollitup.org/t/various-led-testing-and-extracting-data.833907/

http://rollitup.org/t/photosynthesis-under-solid-state-light-setting-the-standards.833449/

I'd watch SDS he's been paving a path for us laymen.