What options do IIS/Windows users have?
Once the well-known URL on your domain is setup to route to the ACME client, then you probably want a command line client (I like 'lego') scripted to run periodically and check which certs need refreshing. The last step is getting to certs back into IIS and bound to the specific site, which can be done in Powershell.
Overall it's fairly straightforward but will take hours to get it fully working and it does adds a few moving parts to your setup. I'd say not enough ROI if you need less than a dozen certs.
Certify is a Windows app which uses Let's Encrypt to provide free trusted SSL certificates for websites you control.