<<I'm not sure what you have against an independent 12-volt system, but I'd love to hear you elaborate on the cons. Running separate 12-volt lines, together with a solar panel array and a series of deep-cycle marine batteries is a good way to supplement your grid power, especially in an area where the grid is frequently out or intermittent. Converters are an option, and are ok when the 110 is on. But the energy lost due to inefficiency is too high for coverters to be relied on in a "survival" situation, or one I like to call "Fort Homestead". The websites mentioned elsewhere in this thread can tell you about 12-volt systems, and you can search the web under RV equipment to find what equipment and appliances are available.>>

I don't have anything at all against 12VDC <grin>. You're reading too much into what I wrote. Put it back into the context of the original post and my reply to the original post. Or you can suffer through another of my lengthy posts, which follows:

So to answer you... I have first hand experience with DC appliances, generators of many sorts and configurations, and inverters (both mechanical and solid state). Plenty of experience with what the RV world offers in the way of propane, 12vdc, and line voltage gadgets.

Here's a thought: Where every gram counts, does NASA use 12vdc? NOPE. Wires and motors would be too big. 12vdc is an expedient for a home; there are not many compelling reasons to do a lot of expensive preparatory work to use emergency 12vdc. Actually, there aren't a lot of compelling reasons to use 12vdc in automobiles anymore, either, and I suspect we're about to see some regulations about that melt away. If DC is the flavor, there are plenty of good reasons to kick the voltage up. And something like, say, 120 volt, is no harder to get from solar panels than 12 volt because neither 12v nor 120v is the "native" voltage of a solar cell - 12 volt panels are groups of cells connected in series rather than parallel in order to kick the voltage up to 12 volts.

Efficiencies. Hmmm. Perhaps, but so what? It's not as bad as most folks think, and don't forget that one does not simply wire solar panels to batteries - unless you like to replace batteries VERY frequently. They run through a solid state battery charging control station of some sort - which is no more or less intrinsically efficient than any other circuit. The lower the voltage the less efficient that process is. Kick things up an order of magnitude and we'll talk - read on.

The choice of low voltage DC is more like a lifestyle choice (unless one has unlimeted resources). Is 12vdc handy? Yeah, for a few things like expedient or emergency lighting (automotive lightbulbs, auto batteries, RV stuff, etc.) But serious work? No way! The amperages required are huge, and therefore so are the conductors. Power for DC is the simple product of voltage and amperage. (It's a little more complicated for AC and I won't drag folks thru a beginning juice course to yak about RMS blah blah blah) I'm too lazy to go drag out some of my "Producing Your Own Power" type references, so I'll do this on the fly:

For example take a washing machine, which typically has a 1/2 hp motor (SAE HP; SI HP is smaller). That's close enough to 1/2 of 746 watts, or about 373 watts. We won't dicker about "is that output?" (usually it is for NEMA AC motors) or input (which would be a larger value). I'll just stipulate that the motor will use up to 373 watts. At 12vdc that means it would take over 31 amps to run the motor at its rated power. The same motor in 120vdc would take a little over 3 amps. (And the required amperage for 120vAC is similar). THERE IS NO WAY AROUND THIS if you use low voltage appliances that do the same work as standard household voltage appliances. TANSTAAFL. If you want a kw-hr of work performed, you gotta put in a kw-hr worth of energy plus losses. A 31 amp circuit would take a MINIMUM of dedicated 10 gauge wires (NOTHING else on the circuit), and that's for a short run (and on the margin for safety - those will get warm). And 1/2 HP is nothing; your toaster draws more current. (A LOT more). I have on more than one occasion melted 6 foot long 00 gauge cables off the battery terminals feeding a 2hp nominal 12 volt dc motor. Melted.

Speaking of losses - except at extremely high voltages, there are significant line losses with DC compared to AC. There are wiring runs of over 100 feet in typical houses from the distribution panel to the point-of use - and I'm not including the 100 foot extension cord used to run the weed whacker (or whatever) - I'm talking about the hard-wired circuits. There will be a significant voltage drop which kicks up the amperage requirement which kicks up the conductor size required... it's a vicious cycle. Bottom line is that conductor size must get very very large.

Even blowers/fans suck amps on 12vdc. Ever notice that most automobile blowers (small as they are) have at least a 20amp fuse on them?

And there is a whole 'nother area: an appliance is either 12vdc or 120vac; it cannot be both. There ARE some types of motors that will run on either AC or DC and some small appliances and hand tools use that type of motor BUT it does matter what the voltage is. A dual voltage household implies duplicate appliances - or there is little point. That, plus wiring, is pretty expensive, not to mention taking up a lot of space.

Because there ARE a lot of 12vdc gadgets around, it may make some sense for some situations to have some things that run on 12vdc. Sump pump? Sure; there are models available that are 12vdc because they run off a storage battery that is kept charged by line power. Lights? Sure. Just use standard auto stuff and/or RV stuff. For example, I've got 12vDC standard light bulbs - low wattage - that screw into my regular trouble lights and a few gadgets I made up let me connect them to a 12vdc source. I also have a few RV 12vdc flourescent light fixtures - oops! Actually, they have an integrated solid state device in them to kick the voltage up, but they LOOK LIKE they require 12vdc. (Actually, running a similar output standard flouro light fixture off a separate inverter is more efficient, which is one reason why I stopped scrounging those particular RV fixtures)

And I have a few 12vdc tools left around because it was convenient for me when afield - but I also have moved away from that to (for now) an on-board invertor and mostly use standard tools when afield now. Plus I have a 4kw genset anyway because my power DOES drop out regularly even though I live in town. (I choose not to hardwire my genset as I sometimes use it portable - even at home, where the 120vac line loss to the back of my property makes it impractical to lay an extension cord to run something like a circular saw drawing around 13.5 amps). I probably will add on-board welding/line power to a couple of my vehicles in the next year or so - but the line power on those actually comes from some solid state wizardry. About the only 12volt "appliance" I might retain is on-board compressed air - depending on the vehicle (not enough room under the hood in one for engine-driven compressor)

I think some solar panels to charge a modest battery bank to power some selected low voltage light circuits is fine, although the total cost will be equal or greater to what a genset costs. I helped do up some "Mother Earth" type homesteads with 12vdc stuff in the past and the best I can say about them is that they were spartan. None of those places that are still occupied are on 12vdc today - it doesn't work out well. Even then it was an exercise in what could be done rather than what should be done. I'm richer for having learned how to do those things - I can "McGuyver" more things as a result - but I learned more about how NOT to power a household than anything else.

That's a whole lot more than 2 cents worth... as I wrote up top, I've got nothing against 12vdc. But put my response in context, please.

HTH to explain my post because this is all I care to write on this topic, LoL!

Regards,

Tom