most efficient way to light, given a 48vdc pv system?

 

I am trying to light an off-grid house that had 60% of the lighting
configured for 12vdc, (large gauge wire feeding to a distribution
center in the middle of the house). The seller says that 12v lighting
is more efficient than 110vac, the inverter doesn't need to run at
night. Given my 48vdc system, what's the most efficient way to light?
I'm assuming that it's either a 48v to 12v converter, or reconfigure
the system and go with purely 110vac from my inverter, (xantrex 4048)?
I'm deep in Baja and would really appreciate some help from this group.
I am not beyond snivelling if that would expedite some assistance.
Thanks,
Per

 

t38 wrote:

I'd say that the seller is sort of right, sort of wrong. An inverter is
more efficient the greater the load. And, a 48v to 12v converter is
going to lose some power in the process.
I assume you'll be running a lot more than just lights at night? Maybe a
TV, a DVD, a stereo maybe?
Compact (110vac) fluorescents are the way to go.... if you're running a
tv as well as a light or two.
12v wiring is a lot more 'lossy' than 48v also.
It's a good idea however, to keep a few critically placed 48v. lights in
the system, just in case the inverter decides to die one dark night.
Wire them up to pull switches.

 

Wow, that was quick, thanks! Assume that half of the power load is
lighting. Is it more efficient to light through the inverter to compact
flurescents, or through a converter to 12v lighting, and now you bring
up a third option I was unaware of - 48vdc lighting?

 



Just a quick comment - there are two issues here - efficiency and
cost.
I suspect that a 48v to 12v (dc-dc) converter will have much the same
efficiency at the inverter - but could be more costly. However it
would mean not needing to change the existing 12v system,

The inverter could possibly be cheaper, and the mains-voltage cf's are
readily available.

I don't personally know of any cf-type 48v bulbs, though in NZ 50v
incandescents have been available (used by telecom). However, these
are not very efficient.

If approx half of your load is lights - what is the other half? Is it
12volt loads only? And what max wattage do you expect?

Eric

 

t38 wrote:

I did a quick google search and found a number of 48vdc fluorescent
lights, although they were rather expensive and somewhat harder to
find than 12V or 24V lights.

Another alternative, apart from just going to AC, would be to rig
up a separate 12V system just for the lights. If it's just a few
lights then it need not be particularly large or expensive.

Anthony