Located between solar modules and the power grid, the solar inverter is the heart of a solar installation. It converts direct current from solar cells into grid-compatible alternating current. With grid-independent power, it forms an independent power supply for all AC-operated electrical appliances into which further solar inverters can then also feed. This is also the case for backup systems.
However the solar inverter does not only function as a current transformer. As the multifunctional heart of a wide variety of photovoltaic systems, the solar inverter also fulfils a wide range of other tasks:
- Monitoring and controlling of the entire photovoltaic system
- Helps achieve maximum performance
- The recording of all operating data
- For grid-connected systems, automatic disconnection from the grid is possible if required
- Interruption of the grid supply
- Protection of the network against overloading
- For mains-independent backup systems, switching from mains to emergency power within a few milliseconds in the event of a power failure - for an uninterrupted power supply.
Numerous inverters in various performance classes are available on the market. Your IBC SOLAR specialist partner knows the differences and will know which one is right for you. They will also ensure the correct installation at a suitable location.
What is a solar inverter?
A solar inverter has the important task of converting the direct current generated in the solar modules into alternating current and making it usable for the public power grid. It is therefore an indispensable part of the photovoltaic system: the operation of electronic devices with solar energy is only possible by means of current conversion.
Inverters have an input side (for direct current, abbreviation: DC), which has one or more DC controllers with MPP tracker that are controlled by a microprocessor. In the next stage, the actual transformation of the energy takes place in the form of alternating current (abbreviation: AC), which is subsequently passed on to the output side. From there, it is stored in the power grid. Inverters are available in various versions. Nowadays, there are models with or without transformer (transformer). However, modern inverters often have no transformer and thus have a higher efficiency. In addition, a distinction is made between three different inverters for photovoltaic plants. These are briefly described and explained in more detail.
Solar inverters: models and designs
Inverters for photovoltaic plants must meet a number of requirements in order to profit economically in the long term. Modern models are quickly and flexibly adapted to the amount of solar energy generated, e.g. changes in cloud cover and weather fluctuations. The solar inverter should achieve its highest efficiency both at high and low input voltages. Depending on the size and location of the photovoltaic system, the respective inverters need to have different characteristics. Always applies: The inverter should be matched to the photovoltaic system in a manner appropriate to the needs of the customer.
This type of solar inverter is connected directly to the respective solar module. Each solar module thus has its own inverter. Microinverters are used mainly for small solar systems or for solar systems with different orientations of the solar modules.
Several solar modules are interconnected in series and form a strand (or string). A string inverter thus connects a whole series of connected photovoltaic modules to the public power grid. This form is now widely used as it offers a wide range of applications and a good price / performance ratio. String inverters are suitable for small household systems as well as for large free-standing systems.
A battery inverter allows the combination of a solar system with a storage system and intelligently regulates the charging and discharging of the solar battery.
Hybrid inverters are a combination of photovoltaic and battery inverters. This unites two devices in one and thus saves space and costs. In addition, they often offer the possibility of a back-up function.
Solar inverters and MPP tracking
If you are looking for a powerful solar inverter, do not miss out on MPP tracking. MPP stands for "Maximum PowerPoint" and indicates the point at which a solar module performs its highest performance. This depends on the solar radiation, the temperature and the individual properties of the solar module. MPP tracking is therefore a matter of continually recording the performance of the photovoltaic module and adapting it to the respective circumstances. The MPP Tracker ensures that the maximum amount of energy is always produced. It is controlled by a microcontroller, in which a certain setpoint is pre-determined. Due to the importance of MPP tracking for photovoltaic systems, modern solar inverters often have more than one MPP tracker.
The solar inverter and its efficiency
The efficiency of the solar inverter is of central importance for a photovoltaic system. It provides information about the maximum energy conversion of the entire plant and decides decisively on its yield and the associated profitability. The level of efficiency is dependent upon many factors, e.g. the solar radiation, and the location of the PV system and the system configuration. The solar inverter therefore does not always provide its full power and the same device can have a different efficiency at different locations. In order to make the equipment comparable, the "European Efficiency" was introduced some years ago. This represents an average of the efficiencies at different partial capacities (5, 10, 20, 30, 50 and 100 per cent of the maximum power). The weighting of this value takes place taking into account average European temperature and weather fluctuations.
Where is the solar inverter connected?
Several factors play a role in the choice of the correct placement of the solar inverter. In principle, it should be protected from wind and weather, which is why installation in the house interior, e.g. in the basement or in garages. And here, too, there are specifications: among other things, the ambient temperature is crucial for the installation of the solar inverter. In the case of the conversion from direct current to alternating current, losses occur which are emitted in the form of heat to the environment. In warm rooms, the heat cannot be dissipated correctly over the air. Higher temperatures influence the life of the device and its electrical components. Close proximity to the ceiling or other inverters can limit heat dissipation. Fixed minimum distances should ensure safe operation of the equipment. Another factor that should be taken into account during assembly is the noise level generated during the transformation. Although modern solar inverters usually operate very quietly, there may be occasional buzzing or clicking noises at high power. For this reason it is advisable not to install the unit in the immediate vicinity of the living rooms. Last but not least, the distance to the feed-in counter is of particular importance in the case of string inverters. In principle, installation of an inverter should only be carried out by persons with a professional knowledge.