How To Choose Your Solar Inverter?

The solar inverter is the central part between the two energy sources to which your photovoltaic installation is connected: your solar panels which produce direct current and the network in alternating current. Choosing an inverter is therefore an important step: it will depend on the use you will make of your installation. In order for you to optimize the electrical performance of your solar panels, here is what to take into account before making your choice.

CHOICE OF POWER

On the inverter data sheets, you will find (at least) two types of power indicated: nominal power and peak power. The nominal value corresponds to the maximum power that the inverter can deliver continuously over a long period of time. In order to calculate the rated power you will need, add up the rated power of your electrical appliances that may be operating at the same time. The total must not exceed the rated power of the inverter. Investigate electroever.com website for more detais.

As for the peak power, this is the maximum power that an inverter can deliver for a few seconds (5 in principle). It is in a way its capacity to respond to the high starting currents of certain devices such as refrigerators, freezers... According to the same logic as before, the peak power of the inverter must be greater than the sum of the powers. start-up of devices capable of starting at the same time AND the nominal power of devices operating continuously.

Once these calculations have been made, a margin of 20% must still be allowed. Some people will advise you to oversize your inverter, in case you have to connect other consumers later. Be careful, however, not to overdo it in order to optimize your performance.

CHOICE OF VOLTAGES

The DC input voltage must be greater than that of the generator (solar panels) and the battery. The output voltage must correspond to that of the devices used, in principle 220 / 230V.

YIELD

The efficiency of an inverter is the ratio between the useful power and the power absorbed by the converter, ie the power it consumes for its own operation. This yield varies in principle between 95 and 98%.

SIGNAL FORM AND INVERTER TYPE

There are "Pure Sine" inverters which produce a sinusoidal signal conforming to that of the electrical network, and "Pseudo Sine" inverters. A third type of inverter, square wave is also on the market but offers a low quality signal and can only be used for small loads.

It is in particular in this choice of the type of inverter that the use which you will make of your installation comes into account. Ideally, inverters delivering a pure sine wave provide optimal operation. But for some devices, a pseudo sinusoidal wave can be sufficient as for light bulbs, computers or even the Tele. Another criterion to be taken into account: the price, "Pseudo Sinus" inverters being in principle less expensive. Finally, if you have chosen to resell your electricity to the network manager, prefer a specific inverter for network coupling.

TRANSFORMER OR NOT?

The last choice to be made will be to take an inverter with or without a transformer. On this subject opinions differ. The transformer isolates the network and the photovoltaic field. It is therefore an additional security, which makes the system less exposed to surges, whether they come from the network or solar panels. They are recommended for thin film sensors and low power systems.

However, the transformer induces a reduction in efficiency. Some therefore prefer inverters without transformers which use other techniques for compensating leakage currents, particularly to earth.