efficient power transmission

[TheCasualTraveler]

OK, now this is coming from a newbie with enough electronic experience to make him dangerous or at least make you very nervous if I was poking around your stuff. That said, irascible experts may want to point and click somewhere else. Curious experts please read on.

I've been wondering about this for some time and have tried to research it but may not be using the right words, or I found the answers and just don't understand them. At any rate I wonder why we use power the way we do by storing it at 12 or 24  (or 48) volts DC and then running it thru an inverter to make 120 AC. Given, I know the basics about higher DC being more efficient than lower DC, that AC is more efficient than DC and that higher voltage AC is more efficient yet. I keep imagining different circuits that may exist or maybe were tried and failed. Like these,

When I was young I built a small circuit that I believe had a battery, a resister, a capacitor and a small neon light. I think the way it worked was the battery would charge the cap which when it reached a certain voltage would discharge into the neon lamp and make it flash. There may have been a diode in there somewhere. So I think of that and wonder why we use transformers to get higher voltage (AC) from DC. Is it ever done thru a simple circuit, or maybe two parallel circuits charging and discharging caps and routed in a way to produce 120 AC. What I imagine would look pretty much like one of those desulfator circuits with the 555 timer and two power transistors. Are there such things? Are they used for conversion?

Another idea I had along the same line was to make use of lower voltages from wind turbines, waterwheels etc. Instead of having a cut in at 12 volts or so have the power at 2 volts flow into six parallel circuits that again charge a cap up to two volts at which point an electronic switch is thrown putting the caps in series and dischaging a pulse of 12 volts and then back again.

Also I was wondering if there is a simple efficient way to turn 120 volts dc to 120 volts ac without the transformer. (I keep picking on the transformer because I assume it wastes energy. Maybe I'm wrong) I thought maybe the best setup for solar was to have as an example, the array feeding into 10 - 12 volt deep cycle bats in series that get converted to 120AC

I expect the typical response to this may be, "we discussed this to no end back in, yada yada, go search..." So if it's back there I'd like a link to it. Otherwise if it's possible, then I'm sure it's been tried. And if not used there's a reason and I'd love to hear what they are. Thanks for listening.

[TAH]

Storing power at lower voltage has many reasons I suppose. One of the biggest is probably safety in that the voltage is much less likely to arc or break through insulation. Another reason probably has to do with electrical codes that change for higher voltage systems. AC is somewhat easier to work with at higher voltages. The equipment I work on pretty much all switched to DC 15 years ago and there is all sorts of new and fun problems with it but that is 100kv plus. You don't need a transformer to turn DC to AC, you use a transformer to isolate or step AC up or down. DC and transformers don't work together. You can make 120 VDC into 120 AC with a couple of relays if you really want but there are losses there too and they will burn up and also 120 VAC line power is RMS the voltage peaks are around +170 volts to -170 volts switching 120VDC would only get you the equilivent of about 84 VAC.

[TheCasualTraveler]

Yes, I realize DC doesn't work in a transformer. What I meant was isn't the whole process more efficient to do without the transformer? I suppose an inverter has some sort of switching circuit to turn the DC to AC before the transformer (or does it only make pulsating DC?) Do I understand then that you need approx. 170 Volts DC to convert to 120 volts AC RMS? That would make for a large bank and scary DC voltage. I'm starting to see things are done the way they are all centered around storage. What you wrote gives me more understanding to research and where to look, thanks.

[TAH]

Transformers are not the part of the system to worry about. There are a lot more losses in the batteries and other places.

If you were going to try to produce 120 VAC equilavent without a transformer th easiest way would be switching 170 VDc but that is going to give you a square wave. There are other ways to do it and you are not likely to come up with a better way than a good inverter. You are only dealing with a 7% loss on some inverters. The loss in the batteries can be a lot more than that.