Posted by F Murtz on June 20, 2011, 3:03 am
The Other Mike wrote:
Try this, and oatleyelectronics have lots more goodies.
Posted by Tabby on June 20, 2011, 3:43 am
On Jun 19, 11:52pm, The Other Mike
I think you'd benefit greatly from zooming out for a rethink. You'er
asking for low voltage panels to charge a 12v battery, which will then
get upconverted to 240v which must be done the expensive sine way,
which will then be downconverted to 35v to run the tubes. Its madness.
Far more practical wuold be warm white LEDs that will run off 12v via
a resistor or constant current regulator. Take a look at
rapidonline.co.uk, if you can wade through the long list of led
options you'll find some very satisfactory deals there. No need for a
240v invertor anywhere, or problematic ballasts, no compatibility
issues, and LEDs are far longer lived, far more robust and much more
versatile than fl tubes, and trivial to dim to save power.
Posted by The Other Mike on June 20, 2011, 11:31 am
I can't see the economics working, yes its wasteful with multiple
stages of conversion but the fluorescents are already there, also
LED's seem way more expensive because of the number of light sources
Dimming isn't a requirement. Its for work lighting as its a near
windowless building, the requirement is for an even spread of light
such as provided by a fluorescent tube (operating microscopes and
laptops in the same room is very common occurrence)
T5 fluorescents are somewhere around 70-100 lumens per watt. Most
LED's at appear to be much lower efficiency with a holey spectrum and
providing a very directional light source. but I'll ignore those
deficiencies for now.
Currently there are I guess somewhere around 17000 lumens lighting an
area of about 20 x 8ft so make that around 1000 lux, but we might get
away with a little bit less.
At about the typical "90 lumens" per white LED package that would
require about 180 separate light sources costing anything from GBP 2 -
4 a piece. All requiring heatsinking and being around 1/3 the
efficiency of the fluorescents, almost certainly requiring a bigger
solar array and a bigger battery.
So before those LED's are mounted and wired that's GBP 500 - 700 for
the equivalent of the fluorescents that are already in situ which cost
significantly less than a 10th of that.
GBP 500-700 buys a very nice pure sine inverter.
Posted by Dave Liquorice on June 20, 2011, 1:36 pm
On Mon, 20 Jun 2011 12:31:37 +0100, The Other Mike wrote:
LED lighting is evolving very quickly, you can get strips these days
with LEDs mounted every few inches, rather individual "bulbs".
I wouldn't like to say how their efficiency compares to florry
Or there are GU10 LED or R50 sized reflectors that only take a watt
or two at mains voltages. The aldli/lidl 3W Warm White 3000K LED R50
ES "reflector" I got to try is a pretty close match to a 60W R50 ES
Directional of course not spray light everywhere like a florry.
Posted by Tabby on June 20, 2011, 2:20 pm
On Jun 20, 12:31pm, The Other Mike
Rapid do white LEDs for 1.50 per 100 lumens, 17000l in whites = 255=
Colours are cheaper, except blue which you wont need, there's plenty
of that from the white LEDs.
Spectrum is addressed by mixing white LEDs with coloured ones to
create the white you're after.
Directionality is a nonissue with uplighting.
Ali sheet's not expensive
If yuo'd rather go with the T5s, you either need a sine wave invertor
or some electronic ballasts. Those and HID are the options really.