the problem with LEDs is that they usually need resistors and resistors heat a lot = electricity wasted.
also if you have to transform 230 volts into couple volts: it is very not good idea.
as i have planned new generation earthship one thing is that the battery reserve would be sincle 1.5 volt cells and you just would have simple switches to turn them off or on to increase voltage.
therefore we would not need electronics between to regulate the voltage and reloading the single 1.5 volts unit is fast and can be done simply with hands by turning motor with simple circuit basically just diode between, you just need voltage meter to monitor not to spin too fast or too slow.
also solar panels can be made to reload the cells with same simple mechanism that in sunny days you can reroute them to more of cells to reload and in cloudy days you would have to make the switches so that many solar panels would be connected to series in order to raise voltage.
this requires more maintenance but hey, who told life would be easy? it will be cheaper and more efficient so it saves electricity.
also the problem in LEDs is heating.
in fact LEDs cool down (same as peltier-element) in low voltage. therefore blinking the LED lights is best way, and if you blink two lights in exact order: there will be 100% light for the eye, as one turns on when the other turns off.
now we dont need anymore cooling down the LEDs and when they are below normal LED temperatures (60-100 celsius) they last instead of 100 000 hourse maybe 10 million hours as heat is the primary effect which degrades LEDs.
also, the more cool LED is the less electricity is turned into heat as it sucks up more electricity, as it heats up when resistance increases in heat.
as we blink the LEDS, they cool down themselfs, use less electricity and last longer.
the circuit for this is simple and about like this (basically the joule thief just "blinks" the current and loads and discharges the condensator very fast so the same mechanism could be used to blink the LEDs)
12 volt systems are based on the voltage of lead acid cells (2 volts) that make them up. At one time 6 volts was the chosen voltage. They kept upping it to match our ever increasing hunger for more. Most dc voltages are multiples of 2 and 3. Voltages increased so wire size could remain small enough to be affordable. You reach a point though where high dc voltage gets scary. The solution was ac which transported easily and did not arc. No evil, just the solution to a problem of the day. Electricity is a series of tradeoffs and conventions developed over time. The only weakness of your low voltage household would be the size of wiring required to carry a larger amount of power. For a small localized system with limited amount of leds it could work. There are already a lot of rechargeable lanterns on the market that use the USB plugs and connectors for recharging and powering devices. I believe they are in the 5 volt range. Up to about 3 amps... not a bad amount of light... As to resistors they are not put in the circuit by evil corporations they are there to regulate current through the diodes so they don't self destruct. Heat is the tradeoff to drive the led. Simple dc led arrays use resistors and fixed dc voltage. Large complex leds use voltage adjusting drivers. Lifespan is a function of resistor sizing. Cheap leds oversize the resistor to overdrive the led shortening life but producing more light for less time. So buy good ones. I have led bulbs in daily use for over 8 years. I can now buy the same bulb for 1/10th the price.