If you only want storage to access inside your house then look at network attached storage (NAS).
these don't have to be big servers and don't have to be power hungry either.
they range from really simple NAS devices, (I've got a USB disk with a network port, so can either be USB or network storage, cost me £20 from ebay and used an old IDE disk to something that is like a small server where you have RAID protection, the ability to schedule backup tasks, possibility of streaming media programs running on the device.
but of course, the more you want to do then generally the more power hungry, and possibly more expensive the system becomes.