I don't have time to do the exact math but think a small inverter and linear fluorescent is a clear winner of your trying to adequately light the bulk of the class room.
Linear fluorescent has lumens per watt in the upper 80's. CFL (DC or AC) is upper 40's and LED is the same as CFL and maybe a little worse depending on whose products you are comparing. You'll also note that it's next to impossible to get Lumens per Watt specs from LED suppliers. It's like the new car company refusing to publish a MPG spec but readily waves a made up spec that alludes to MPG but isn't really. I've been asking the numerous LED manufactures that call on me for samples so I can do side by side testing with CF and LF and NONE of them call back a 2nd time so I'm really still quite nervous about LED for "real" applications. Ok sorry about that LED rant..LED's are cool they are not the panacea they are being made out to be, Two evenly spaced fixtures that use a single 4' tube will almost adequately light the entire room of that size and use about 60 watts total. Total Lumens would be ~5400. Assuming the tare and efficiency losses put the Morningstar 300 at net efficiency of approx 85% that take our lumens per watt to something in the mid 70's which is still much better then DC LED and DC CFL. Best, Travis Creswell Ozark Energy Services _____ From: [email protected] [mailto:[email protected]] On Behalf Of Walt Ratterman Sent: Monday, August 17, 2009 5:34 PM To: 'RE-wrenches' Subject: Re: [RE-wrenches] Solar 12 volt DC lighting for school in Haiti Hello Lee, Walt here. I will be leaving for Haiti in about a week, and be there for three.. We have done lots of schools. If you are strictly 12V, your choices primarily are 12V CF and LED lights. There are lots of pros and cons to both. The real question is what you intend to use the lights for. If you go to our photo gallery (link from home page: www.sunepi.org ), and check out the Sierra Leone gallery, you will see some clamp-on LED Lights that are 12V and are used for night time studying. They are pretty much task lights and are low level. If you are trying to keep the system really small in terms of watts of solar panels, (and cost) these can be great, but again - the primary question is what will the light be used for. A step up from that would be the 12V CFL's. Might be tough to get in Haiti (for replacements). I can check next week and let you know. If you have any kind of distances involved, you will probably want to consider an inverter (Morningstar SS-300 is great) to avoid the losses associated with 12V dc wiring. Feel free to contact me off line if you want to go over this some more.. Thanks, Walt From: [email protected] [mailto:[email protected]] On Behalf Of Lee Bristol Sent: Monday, August 17, 2009 2:53 PM To: [email protected] Subject: [RE-wrenches] Solar 12 volt DC lighting for school in Haiti Can anyone recommend lights for a school in Haiti. I am going there in a couple of months to install a 12 volt solar PV system and need to illuminate seven 16 x 20 foot school rooms. I am so confused by all of the light bulb options, base options, CFL vs LED, what wattage is required, etc. I would expect that two fixtures with bulbs would suffice for a room. Any ideas? There is no grid power available.this is really out in the boondocks. Thanks Lee -- Lee Bristol NABCEP Certified Solar Designer/Installer Chief Technology Officer Standard Solar, Inc. 202 Perry Parkway, #7 Gaithersburg, MD 20877 (301) 944-5105 (240) 479-1510 (c) www.standardsolar.com
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