Why do I need SOL to lock tokens?

All transactions on Solana need SOL for transaction fees and data storage costs.

Blockchain networks such as Solana use a fee-based transaction model to incentivize network validators. Solana fees are among the lowest; most transactions use only a nominal amount of fractional SOLs, which are called lamports. In addition, transactions that need to store persistent data on Solana need to pay rent for the privilege of doing so. 

The act of locking POLIS, ATLAS, Star Atlas assets, or other SPL tokens requires a small amount of rent to create escrow accounts associated with the various locking programs. In the case of the POLIS snapshot and rewards programs, additional accounts are needed to store users' calculated voting power for the duration of the lock. These fees are approximately 0.015 SOL per era, each of which runs 256 days. In other words, in addition to a nominal SOL transaction fee, you will need to pay certain amounts of SOL when locking tokens, such as in the following examples:

  • A total of 0.133 SOL to begin a full five-year lock (for escrow for eight 256-day eras)
  • Certain escrow fees to extend a lock (0.015 SOL per additional 256-day era)
  • Zero SOL to compound rewards (other than the nominal transaction fee)

In most cases, such as with SCORE, the escrow accounts associated with locking are automatically reclaimed when exiting the program. This is not the case with POLIS voting power snapshots, as at this time the program is designed to store this data in perpetuity.

Storage Rent Economics (Solana Documentation)