The table below has a selection of LEDs that are easy to obtain from online vendors. The luminosity data is that supplied by the manufacturers and I have no way of verifying it as I do not have a light meter yet. I included a 4ft fluorescent tube that works with 220 - 240V ac for comparison otherwise I would only like to focus on lighting that can be powered by DC battery charged by renewable energy sources like PV (solar) panels, wind, pedal powered generators etc.
Please scroll further down the page to see the table
|LED||lumens lm||power W||area sqcm||cost||lm/W||lm/$||lm/sqcm|
|CREE XR-E on star base||110||1.30||2.84||$6.00||84.62||18.33||38.80|
|CREE XR-E on star base||228||3.50||2.84||$6.00||65.14||38.00||80.42|
|high power chip on base||60||1.00||0.38||$2.75||60.00||21.82||155.91|
|240VAC 4ft flourescent||2500||36.00||304.20||$2.00||69.44||1250.00||8.22|
If we are to believe the data supplied by manufacturers then one can easily see that the 4.8mm wide angle (120deg) LEDs are easily the most efficient lights here in terms of lumens per watt. They also have the advantage of not generating so much heat compared to the CREE LEDs for example. They also knock the socks off anything else in terms of lm/$ and lm/$. I am waiting for some of these LEDs to arrive so I cam construct an LED array of 105 of them on a 63mm X 100mm (2.5" X 4") stripboard (prototype board). I have already built such arrays but with cheap and nasty LEDs of dubious origin. The arrays are driven by constant current circuits. I will show you how to make both the arrays and drivers though the drivers can be bought online for a few dollars but it is more fun and practical to make your own if ordering from the web is a difficult due to lack of payment options (a big problem especially where these lights are most needed).