We may want to estimate the profit of renting storage vs electricity cost.
Say that you have a PC with Celeron CPU and 2x 6TB internal hard drives and you leave it running 24/7 just for SIA.
How much is it going to consume ?
Assuming that you rent all your 6 TB at 12-15 $ / month ($2/TB/month) , i am not sure you can cover the energy costs, because it depends on the disk reads/writes operations done in that month, as the disk too consumes power based on I/O activity.
You can connect lots of HDDs. I think each HDD is 5-10W, idling system is 50-100W, depends on configuration and components.