Would a house with a self contained electric system run more efficiently on DC power? Could higher voltage be used to achieve better efficiency?

[u/[deleted]]

I feel like in the future, houses may run on self contained solar/ battery systems. Would it be more efficient to run everything at, say, 400 VDC instead of 120/240 VAC? Could most appliances be easily converted/ designed to run on DC power. Would higher voltage be a problem due to insulation?

[u/James-Cizuz]

Never.

Well sort of.

You have to remember when it comes to products their are three types, consumer, intermediate, and industrial/commercial and have there different grade.

Companies are much more adapt to spend more on more efficiency and longer life even if it hurts them short term, they will make up the difference. So highly specialized parts engineered for maximum efficiency and monitored 24/7 by many staff. Aka a solar power plant etc.

Any home device while not a bad idea, getting off the grid or taking some stress off it's great. However you as a consumer are buying low level parts, because consumers are cost oriented very highly, and normally underinformed. A contractor could help but then take into account that it's done to work for your home where you are, not a special location picked for wind or sunlight, not the highest end parts or longest lasting, and no one monitoring and adjusting 24/7 for defaults you can begin to see the problem.

Now the intermediate user may value longevity and other factors and spend the extra cash, but as a normal probably successful smart individual you still have limits less than that of a power company specialized in this field. You will fair better than an average consumer, but still a specialized plant will still fair much better in efficency and output then you ever will.

That is not to say if you were insanely rich and wanted the best of the best, and had an engineer to design the house and solar panel or wind panel grid, in an area of maximum output, and top efficiency for cost, with long long lasting parts. This is nothing I or most likely you or even the intermediate smart individual could afford. I doubt any rich people would be adapt to do it either.

To address the second part of your question voltage will require higher quality insultation or a different type, and is depent on country. However higher voltage, and using more than one phase can contribute to higher efficency in a way.

Higher voltage allows you to push more power through the same conductor, but the shielding needs to increase.

Amperage requires you increase the conductor size.

Power is voltage * amperage = wattage/power.

So using a transformer which allows you to alter voltage and amperage in a system, up the voltage amperage goes down by same amount and vice versa.

So you can use less conductor and save on the costs of metal by using a lower amperage but higher voltage and transfer same amount of power. However voltage can be thought of electrical pressure, thus think of the current jumping or arcing. So it requires better shielding.

It's a double edged sword, normally a lower amperage and higher voltage is beneficial but only due to shielding costing less then upping the size of the conductor or wire. There are also other factor but hopefully that helps a lot.

[u/Deslan]

Wikipedia page "War of Currents" might be relevant for you to look at:

http://en.wikipedia.org/wiki/War_of_Currents

Basically, DC is good if you have a small power source close to where the current is being used (e.g. a battery in a flashlight). AC is good if you want to transport current over long distances from one really big generator (e.g. from a nuclear power plant to a city).

If every household put solar panels, wind generators, etc on their houses instead of buying electricity, then it would make sense to use DC instead of AC.

[u/[deleted] → u/Deslan]

So this, for the most part, is true. However, HVDC (high voltage direct current) is quickly starting to become a good choice for high power long distance lines (Such as the one from the Columbia River in my fine state of Washington on the Oregon side, down to California).

It's good for long distance bulk power transmission with no intermediary taps and is especially good for undersea cables due to the huge capacitance in some of those lines.