To determine the extent to which ERG S.p.A. should utilize hybrid bonds relative to the S&P Global Ratings' 15% equity credit cap, we evaluate the company's financial position at the end of 2022.

1.  **Adjusted Capital Calculation:**
    *   **Equity:** The Equity attributable to owners of the parent at the end of 2022 is 2,045,350,000 EUR.
    *   **Debt:** The company reports "Other Noncurrent Financial Liabilities" (1,751,255,000 EUR), "Noncurrent Lease Liabilities" (150,955,000 EUR), "Current Financial Liabilities At Fair Value Through Profit Or Loss" (76,644,000 EUR), "Other Current Financial Liabilities" (389,716,000 EUR), and "Current Lease Liabilities" (6,362,000 EUR). Summing these total debt items provides a snapshot of the debt burden, which is significant relative to the equity base.
    *   **Total Capital (Debt + Equity):** This base is approximately 4.4 billion EUR. 15% of this total capital is roughly 660 million EUR, representing the potential S&P hybrid equity credit ceiling.

2.  **Financial Context:**
    *   ERG S.p.A. has demonstrated strong cash flow from operating activities (458,926,000 EUR in 2022) and holds a solid cash position.
    *   The market environment in 2022 showed a sharp increase in interest rates across all swap curves (5Y, 7Y, 10Y) compared to 2020/2021, and the cost of debt as indicated by the iBoxx Euro Non-Financial IG spread has risen significantly (from 1.298% to 2.295% on average).
    *   Given the rising interest rate environment, issuing new debt is increasingly expensive. Hybrid bonds offer a mechanism to enhance the capital structure, supporting credit ratings by receiving equity credit, while providing flexibility in a high-rate cycle.

3.  **Strategy:**
    *   The company has significant financial liabilities and is currently in a capital-intensive phase. Utilizing hybrid instruments up to the S&P cap allows the firm to optimize its weighted average cost of capital (WACC) and maintain its rating profile, which is critical for a company with such large long-term project commitments.
    *   Given the current leverage and the interest rate outlook, aggressive use of hybrids to the maximum limit is justified to maintain financial flexibility and rating stability.

Therefore, the company should utilize the available capacity to the fullest extent.

<answer>100%</answer>