Solaris Protocol: A Solana-Based Decentralized Micro-Lending Protocol for Financial Inclusion

Abstract

Decentralized Finance (DeFi) lending protocols have demonstrated the viability of peer-to-pool lending without traditional intermediaries. However, the dominant Ethereum-based platforms such as Aave and Compound impose transaction costs of $5–$50 per operation, rendering micro-loans below $1,000 economically unviable for the 1.4 billion unbanked individuals globally. This paper presents Solaris Protocol, a decentralized micro-lending protocol built natively on the Solana blockchain, designed specifically for financial inclusion through micro-lending. Solaris Protocol leverages Solana’s sub-second finality, parallel transaction processing via Sealevel, and transaction costs averaging $0.00025 to achieve a 99.98% cost reduction compared to Ethereum-based alternatives. We present a complete system architecture utilizing Program Derived Addresses (PDAs) for deterministic state management, Cross-Program Invocations (CPIs) for atomic fund transfers, and Rust’s ownership model for memory-safe smart contract execution. Our implementation comprises five core instructions (initialize, deposit, borrow, repay, withdraw) validated through 13 comprehensive test cases covering both success paths and adversarial scenarios. Comparative analysis demonstrates that a $10 micro-loan lifecycle on Solaris Protocol costs $0.00125 in total fees versus $25–$150 on Ethereum-based protocols, establishing the technical feasibility of blockchain-based micro-lending for underserved populations.