Alright, let’s reason through this step by step.

**1. Business profile and cash flow stability**  
EDP is a regulated and quasi-regulated energy utility with fairly predictable cash flows. This supports a moderate use of debt and hybrid capital without excessive risk.

**2. Existing leverage**  
From the balance sheet at end-2022:
- Total equity = €13.83 bn  
- Total debt (long-term borrowings + current borrowings) = €15.78 bn + €4.24 bn ≈ €20.02 bn  
That suggests significant financial leverage, which would make a *high* reliance on hybrids risky from a credit rating and cost perspective.

**3. Hybrid bonds’ role**  
Hybrids get partial equity treatment from rating agencies while being tax-deductible like debt. They are most suitable for firms with:
- Stable operating cash flows (EDP has this)  
- Large ongoing capex programs (EDP has this, given the renewables push)  
- But also the need to maintain investment-grade credit metrics (likely for EDP, given capital market access)  

**4. Market conditions**  
From the provided swap and corporate bond yield data, interest rates moved sharply higher in 2022.  
Subordinated (hybrid) borrowing costs in euros were roughly in the 2.3% range on average for IG non-financials in 2022, which is manageable but no longer ultra-cheap like in 2020–2021.

**5. Practical capital structure mix**  
A 100% hybrid structure would be impossible—no firm finances entirely with hybrids.  
75% would be extremely aggressive and likely jeopardize IG ratings.  
0% might underutilize rating-friendly equity credit and tax shields.  
For a capital-intensive utility with strong cash flows, a moderate share—such as 25%—is realistic, providing equity credit without overloading on expensive subordinated instruments.

**Conclusion:**  
A **25%** reliance on hybrid bonds best balances credit quality, cost of capital, and ratings flexibility.

<answer>25%</answer>