[RE-wrenches] Solar 12 volt DC lighting for school in Haiti

Travis Creswell tcreswell at ozarkenergyservices.com
Tue Aug 18 04:58:43 PDT 2009


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: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] 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: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Lee Bristol
Sent: Monday, August 17, 2009 2:53 PM
To: RE-wrenches at lists.re-wrenches.org
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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