From: Mirimir <mirimir@riseup.net>
   >See
   > [1]http://www.lowtechmagazine.com/2016/04/slow-electricity-the-return
   -of-low-voltage-dc-power.html
   What is said there is logical, but it is impractical.  Society has far
   too much invested in AC transmission systems (including those wires
   already installed in buildings) and consuming devices to expect even a
   small switchover to DC for the vast majority of applications.  In
   Tesla's (and Edison's) day DC was impractical, because there was no
   efficient, reliable way to convert low-voltage DC to high-voltage, and
   back.  (motor-generator sets were the closest to that.)
   In contrast, the AC transformer was very simple, reliable (no moving
   parts), and eventually could be built to step up to 760 KV (and perhaps
   higher), enabling transmission of many hundreds of miles, and then down
   to 240 VAC, split to 120 VAC.  That's why Tesla was right, and Edison
   was wrong.  Edison could never have wired the country with any
   realistic DC system.
   Today, converting DC to  DC is far easier, at least for low voltages,
   see the large set of chips made by Maxim.
   [2]https://www.maximintegrated.com/en/products/power/switching-regulato
   rs.html
   But it is virtually as easy to convert rectified AC to low-voltage DC,
   with these same kinds of chips.  So there is very little reason to
   abandon the modern AC distribution system.  Even a local solar array
   generates a varying voltage that will have to be switched to a specific
   DC voltage to charge batteries, which is easy to do.  And if you hope
   to sell your excess of power to the grid, it will have to be converted
   to AC anyway.
           Jim

References

   1. http://www.lowtechmagazine.com/2016/04/slow-electricity-the-return-of-low-voltage-dc-power.html
   2. https://www.maximintegrated.com/en/products/power/switching-regulators.html