Opensolr now provides a Free Trial membership.

NO CREDIT CARD REQUIRED!
There is no longer the need to register your payment method to get a Free Trial Opensolr account.

The new Free Trial membership, now gives you the option to explore the full Opensolr potential, with the following resorce limits:

• 5 Solr Indexes
• 900 Mb Disk Space Per Each Index
• 10 Gb Monthly Search Traffic Bandwidth Per Each Index
• Backup and replication are also enabled

This should be perfectly suitable to test the capabilities of the Opensolr Cloud Ecosystem.
If you don't have an Opensolr account, click here, to register and get started, totally free.