El Capitan won't install on freshly formatted hard drive...?

Are you trying to install El Capitan from your Recovery HD?

The certificates for several of Apples OS's expired sometime in October, Apple have been very poor at getting these updated on their Recovery Servers with valid certificates. This may be the problem you are experiencing.

Try this workaround, we are going to set the time and date on your mac to a date previous to the expiry date of the certificates.

Boot to your Recovery HD, click on Utilities in the menubar select Terminal.

Enter a new date, for example

date -u 0116180018

press Return

if you get an error try

sudo date -u 0116180018

Now try downloading the OS.

If this works then when the OS is installed and booted up you can Open System Preferences> Date & Time

and reset the time to today.

Some details on the sequences involved here might help, either with a resolution or with an alternative or workaround.

How are you getting to that particular install-time error screen?

Recovery? Most-current-version (⌥⌘R) Recovery?

A bootable installer created on another or previously created on this Mac?

Is the installed disk formatted as GUID/GPT partitioned using Disk Utility?

If you've downloaded what Apple presently has available for El Capitan, did you then build and use the Install OS X El Capitan app?

What if This doesn’t work? As of mine right now.