1. Low-loss conversion
One of the most important characteristics of an inverter is its conversion efficiency. This value represents the proportion of energy that is injected into the DC power supply when it is returned as AC power. Modern devices operate at an efficiency of approximately 98%.
2. Power optimization
The power characteristic curve of a photovoltaic module depends heavily on the module's radiation intensity and temperature-in other words, on values that fluctuate throughout the day. Therefore, the inverter must find and continuously monitor the optimal operating point on the power characteristic curve to extract maximum power from the PV modules under each condition.
3. Monitoring and protection
On the one hand, the inverter monitors the power output of the PV plant, and on the other hand, it also monitors the connected grid. Therefore, if a problem occurs in the grid, it must immediately disconnect the plant from the grid for safety reasons, depending on the requirements of the local grid operator.
In addition, in most cases, the inverter is equipped with a device that safely interrupts the current to the PV modules. Since PV modules are always active when emitting light, they cannot be shut down. Disconnecting the inverter cable during operation can lead to dangerous arcs that cannot be extinguished by DC power. If the circuit breaker is directly integrated into the inverter, installation and wiring effort can be significantly reduced.
4. Communication
The communication interface on the inverter allows control and monitoring of all parameters, operating data, and output. Data can be retrieved and parameters set for the inverter via a network connection or an industrial fieldbus such as RS485. In most cases, data is retrieved via a data logger, which collects data from multiple inverters and, if necessary, transfers it to a free online data portal.
5. Temperature Management
The temperature in the inverter housing also affects conversion efficiency. If it rises too much, the inverter must reduce power, and in some cases, the available module power cannot be fully utilized. On the one hand, the installation location affects the temperature-a consistently cool environment is ideal. On the other hand, it directly affects the operation of the inverter: even 98% efficiency means a 2% power loss. If the plant output is 10 kW, the maximum thermal capacity is still 200 W.
6. Protection
A weatherproof housing, ideally meeting IP65 protection class, allows the inverter to be installed outdoors in any desired location. Advantages: The closer to the inverter the modules can be installed, the less expenditure is required on relatively expensive DC cabling.
