Calculate the exact payback period in years, annual return on investment (ROI %) and 25-year cumulative net profit for solar panels or heat pumps.
Financial Engineering Method: Models compound energy price inflation over a 25-year lifecycle after deducting upfront grants or tax credits.
| Tecnología Instalada | Inversión Media | Ahorro Anual Típico | Retorno (Payback) | Vida Útil |
|---|---|---|---|---|
| Autoconsumo Solar (3–5 kWp) | 4.000 € - 6.000 € | 750 € - 1.100 €/año | 4 a 6 años | 25 - 30 años |
| Aerotermia (sustituyendo gasóleo) | 9.000 € - 13.000 € | 1.400 € - 2.200 €/año | 5 a 7 años | 20 años |
| Cargador Wallbox EV doméstico | 900 € - 1.400 € | 1.200 €/año vs gasolina | 1 año | 15 años |
For DC and single-phase AC circuits, cross-sectional area S (mm²) = (2 × Length × Current × ρ) / Voltage Drop (V). Always verify that conductor ampacity meets NFPA 70 (NEC Table 310.16) or IEC 60364.
Under NEC and IEC standards, the recommended maximum voltage drop is 3% for branch circuits and 5% total for combined feeder and branch circuits.