Low Voltage distribution

[fixit9660]

Hi All,
Only my second posting here so apologies for any transgressions in advance. This is almost certainly a post for the DIY section but since I can't post in there, here goes.
I'm after advice about Low Voltage distribution, as in: If your charging Batteries from PV/Solar and Wind, and your using Low Voltage Lighting, why bother to convert it up to 240v for the cabling/distribution and then back down again for the lights? The losses in the conversion processes are pretty lousy, and they're complex and expensive, I know, I've built a few from scratch. I know/understand that to run 12v over any great distance you need big cables due to the losses, but just around a house? I'm only thinking about using LED lights, not great banks of MR16's to floodlight the garden.
Anyone point me at a website to supply advice and specs please?
Thanks

Andy.

 

[tazz]

If running a few 12v leds then its not a big issue....but its down to old ohms law......if you running 1kw of power at 230v, then your current rating is 4.3 amps, using 1mm cable.....run 1kw of power at 12v, and your current is 83.4 amps, not very practical to run 25mm plus cable around your house, and still would not boil a 2kw kettle....so as voltage increases, current decreases..and vice versa.

 

[Marvo]

.....I know/understand that to run 12v over any great distance you need big cables....

You pretty much answered your own question. Lower voltage means higher current for the same load. Current determines cable size. Big cables are expensive. Only relatively recently low power LED lights mean it is financially viable to have a reasonable amount of lights on a 12 volt circuit because they consume about a tenth of the power their halogen equivalents used to consume so the cable sizes stay sensible.