What is a solar inverter and how does it work?

The panels produce direct current at a voltage that varies with solar radiation and temperature. The inverter takes this current and converts it into 230V, 50 Hz sinusoidal alternating current. In a modern system, it also performs three further functions: it tracks the panels’ maximum power point using MPPT, synchronises the output with the grid where available, and manages the charging and discharging of the batteries if the system has them. Hence, the rated power is not the only figure that matters. A 3000W inverter that cannot start a pump motor is worse than a 2000W one with good peak capacity. A pure sine wave, as opposed to a modified sine wave, is essential for electronics, motors and domestic appliances with compressors.

What inverter power do I need?

Power is calculated based on the maximum simultaneous consumption, not on the total power of everything you have plugged in. Make a list of everything that might be running at the same time during the busiest part of the day and allow for start-up peaks. As a practical guide: a 3,000W inverter is sufficient for a small home or a holiday home with basic electrical appliances and no high-power loads. A 5,000W inverter is the standard for a main residence with an induction hob or heat pump. From 10,000W upwards, we are talking about a large property, a three-phase system or professional use, where the requirement is normally met by connecting several units in parallel rather than using a single unit. The system voltage is linked to the power output: 12V up to around 2,000W, 24V up to 3,000W, and 48V above that. Increasing the voltage reduces the current and, consequently, the cable cross-section and power losses – something you can check using our cable cross-section calculator.

Which brand of solar inverter should I choose?

There is no single answer, but there are criteria that matter more than price: the availability of spare parts, firmware quality, technical support in Spain and the ability to integrate with third-party batteries. We work primarily with Victron Energy for off-grid, campervan and marine applications, where their ecosystem is hard to match in terms of flexibility and documentation, and with Fronius for grid-connected self-consumption, where their European manufacturing and service network make all the difference when something goes wrong. Both are manufacturers with whom we have direct agreements and hold stock; we do not simply act as a distributor.