The most important characteristics of the solar panels inverters are specified by its nominal input voltage, its nominal power, its efficiency and the type of signal it generates. The efficiency of the photovoltaic inverter is a parameter of great importance, as it indicates how it behaves for power levels other than nominal, ie when the load that is connected to the inverter is not the nominal.
In the picture we can see the typical curve of variation of the efficiency of solar inverters SMA Sunny Boy SB3000 in function of the generated power.
With respect to efficiency, what distinguishes mainly some inverters from others is the behavior at low power. This behavior is easy to understand if one takes into account that, in addition to the losses that may exist, the inverter needs to consume a certain power to carry out the conversion process. Another important parameter of photovoltaic inverters is the overload capacity.
The inverter must be able to handle a power several times higher than nominal for short periods of time to allow current points originated, for example, during starting of motors. A final note, which sometimes raises doubts, is the subject of the parallel connection of inverters. The inverters can be connected in parallel to the output, ie on the AC side, up to a maximum number indicated by the manufacturer.
This parallel connection increases the electrical energy exported to the grid. However, it is not usually possible to connect in parallel on the DC side, since it would prevent the proper operation of the MPPT, which involves each inverter and the module (s) to which it is directly connected. As far as autonomous inverters are concerned, parallel connection to the input is always possible, but the parallel connection at the AC output must be approved by the manufacturer. Of course, grid-connected inverters, such as SMA inverters, generate a pure sine wave at its output, compatible with the grid.
Basic installation instructions for SMA inverters:
Despite being carefully constructed, electrical equipment, such as SMA inverters, can cause fires. Some of the basic precautions we must take when installing a solar inverter would be:
- Do not mount the inverter in areas where highly flammable materials or combustible gases are present.
- Do not install the inverter in potentially explosive areas.
- The mounting location must be out of the reach of children.
- We must choose a firm surface for the assembly (for example, concrete or masonry). If you install the inverter over pladur or similar in living areas, during operation it will produce audible vibrations that can be annoying.
- The mounting location must be suitable for the weight and dimensions of the inverter.
- In order to ensure optimum operation of the inverter, the ambient temperature must be between -25 ° C and 40 ° C.
- The place where we install the solar inverter must be protected from direct solar irradiation. Exposure to direct sunlight can overheat the inverter. As a consequence, the inverter would reduce its power.
- When it receives sunlight, the photovoltaic generator produces a dangerous DC voltage present in the DC conductors and the drive components of the inverter.
- Contact with DC conductors or conductive components can cause fatal electric shock. If the DC plug connectors are disconnected from the inverter under load, an arc can be produced with the consequent electric shock that would cause burns.
- The jobs on the inverter should only be performed by qualified electrical installers.
- Do not touch DC conductors or other exposed leads.
- Do not open the top cover of the housing.
- Before carrying out any job on the SMA inverters or the PV generator, always disconnect the inverter from the voltage.
In any case, any doubts that you may have for a correct installation of your SMA solar inverters can contact us, and also to make you arrive budget for your project.