I need to analyze ENEL's financial situation to determine the appropriate level of hybrid bond issuance. Let me work through this systematically.

## Key Data Points Analysis

### Current Hybrid Bond Position
- Existing hybrid bonds in equity: €5,567 million (2023-01-01) / €5,567 million (2022-01-01)
- First issued in 2010, with issuance in 2021 of €3,181 million
- No hybrid issuance in 2022

### Capital Structure (2022 year-end)
- Total Equity: €42,082 million
- Equity attributable to owners: €28,657 million
- Noncontrolling interests: €13,425 million
- Hybrid bonds in equity: €5,567 million (part of equity attributable to owners)

### Debt Position
- Long-term borrowings: €68,191 million
- Short-term borrowings: €18,392 million
- Current portion of long-term borrowings: €2,835 million
- Total debt ≈ €89,418 million

### S&P Credit Metrics (2022)
- Net Debt / EBITDA: 4.84
- FFO / Net Debt: 0.1567 (15.67%)

### Business Profile Assessment
ENEL is a major integrated utility with operations across:
- Regulated utilities (distribution/transmission networks)
- Unregulated power generation (including significant renewables)
- Retail supply

From the data, ENEL has:
- Revenue 2022: €140.5 billion (up from €85.7 billion in 2021)
- Operating profit 2022: €11.2 billion (up from €7.6 billion)
- However, total profit fell to €2.9 billion from €3.9 billion due to discontinued operations losses of €2.3 billion

### Rating and Leverage Context
- S&P Net Debt/EBITDA of 4.84 is relatively high for a utility
- FFO/Net Debt of 15.67% is on the lower side for investment grade
- Moody's adjusted leverage trend: "Improving" - suggesting recent pressure but recovering

### Hybrid Bond Analysis

**Current hybrid as % of adjusted capital:**
- Current hybrids: €5,567 million
- Total equity: €42,082 million
- Total debt: ~€89,418 million
- Adjusted capital = Equity + Debt = ~€131,500 million
- Current hybrid / Adjusted capital = €5,567 / €131,500 ≈ 4.2%

However, using S&P's methodology where hybrids are counted in equity:
- Total adjusted capital = Equity (including hybrids) + Adjusted Debt
- Current hybrid represents about 13.2% of equity attributable to owners (€5,567/€28,657)

Looking at the guidance: "an entity's previous levels of hybrid bond issuance is a strong indicator"

ENEL has:
- Issued hybrids in 2021 (€3,181 million)
- No issuance in 2022
- Has €5,567 million outstanding currently

### Assessment Against Guidelines

Let me check each criterion:

**Funding needs:**
- Significant capex: PP&E purchases €11.3 billion in 2022, intangible purchases €2.0 billion
- Total investing cash outflows: €13.6 billion
- Operating cash flow: €8.7 billion (continuing) + €8.3 billion total with discontinued
- Free cash flow negative after capex
- Need for external financing is clear

**Rating pressure:**
- Net Debt/EBITDA of 4.84 is elevated
- FFO/Net Debt of 15.67% is weak for BBB category
- Moody's notes "improving" trend, suggesting was worse recently

**Cost of hybrid vs debt:**
- Swap curves show rates rose significantly in 2022 (5Y at 1.726%, 7Y at 1.806%, 10Y at 1.927%)
- Corporate bond spreads: iShares Core Euro Corp Bond at 1.085%
- Sub-senior delta for non-financial IG: 2.295% in 2022
- Hybrid costs would be higher but not dramatically so given rising rate environment

**Current hybrid position:**
- Already has €5,567 million in hybrids (about 4.2% of adjusted capital using rough calc, or ~13% of equity)
- Previously issued in 2021, none in 2022

### Key Considerations

1. **ENEL is not starting from zero** - already has meaningful hybrid exposure
2. **Leverage metrics are pressured** - Net Debt/EBITDA of 4.84 is high
3. **FFO/Net Debt of 15.67%** suggests limited headroom
4. **Large capex program** - €13.6 billion investing outflows, mostly capex
5. **"Improving" trend from Moody's** - suggests was worse, now recovering but still constrained
6. **No hybrid issuance in 2022** - despite significant funding needs, suggesting possible market conditions or strategic pause

The fact that ENEL issued hybrids in 2021 (€3.2 billion) but not in 2022 is notable. Given:
- Rising interest rates in 2022 made hybrids more expensive
- Yet leverage remained elevated
- Moody's sees improving trend

The 2022 pause suggests either: (a) market conditions unfavorable, or (b) deleveraging via asset sales/discontinued operations (the €2.3 billion loss from discontinued ops suggests active portfolio restructuring).

Looking at 2023-2024 needs:
- Continued high capex for energy transition
- Leverage still elevated at 4.84x
- Need to preserve investment grade rating

Given existing hybrids at ~4-5% of adjusted capital (roughly), and the 2022 pause in issuance, the most logical step would be moderate additional issuance to:
- Provide rating flexibility
- Not over-extend given already have some hybrids
- Address continued capex needs

The 7.5% level seems most appropriate because:
- Moderate refinancing/capex needs continue
- Rating headroom is moderately constrained (4.84x leverage, 15.67% FFO/Net Debt)
- Would meaningfully improve adjusted leverage metrics (S&P gives 50% equity credit typically)
- Cost will slightly increase debt cost but not dramatically in current rate environment
- Already demonstrated willingness to use hybrids (2021 issuance) but paused in 2022

However, considering the 2022 pause and "improving" trend, and that current hybrids already provide some cushion, 3.75% might be more appropriate if the improvement continues.

But looking more carefully: the Net Debt/EBITDA of 4.84 and FFO/Net Debt of 0.1567 are quite weak for a utility. The "improving" trend suggests it was worse. For an integrated utility with both regulated and unregulated exposure, preserving investment grade is critical. The 2022 pause may have been tactical due to market conditions, not strategic rejection of the instrument.

Given:
- Already has €5,567 million hybrids outstanding
- At 15% cap, maximum would be ~€19,725 million (using equity+debt of ~€131,500m)
- Current is well below cap
- Leverage metrics need support
- Large capex program continues

The 7.5% level fits best: moderate needs, constrained headroom, meaningful metric improvement, and cost increase is slight in context of overall rising rate environment.

<answer>7.5%</answer>