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Choosing system voltage (12V / 24V / 48V)
Calculation3 min readUpdated: 2025-06
System voltage directly affects current flowing through DC cables. At equal power, a 48V system carries 4× less current than a 12V system — allowing much thinner, cheaper cables.
| Voltage | Recommended net energy | Typical MPPT current | Wiring cost |
|---|---|---|---|
| 12V | < 1,500 Wh/day | High (> 100A) | Very high |
| 24V | 1,500 – 4,000 Wh/day | Medium (40–80A) | Moderate |
| 48V | > 4,000 Wh/day | Low (20–40A) | Low |
Forcing 12V for an installation > 2,000 Wh/day generates > 150A in DC cables. This requires 70–95 mm² cables — extremely expensive and dangerous if poorly installed.
SolarDim Pro auto-selects voltage and generates a warning if the engineer forces an inappropriate voltage (VOLTAGE_TOO_LOW or VOLTAGE_OVERSIZED).
Common mistakes
- Forcing 12V "out of habit" on an installation > 2,000 Wh/day
- Choosing system voltage after already buying the panels, instead of the reverse
- Underestimating real startup current (motors, pumps) when picking voltage