Feeding electricity from photovoltaic solar modules into the mains grid requires several special system components. These components enable conversion and capture of the solar electricity and ensure  system safety.
  The ET 250.01 unit contains these components and is conceptualized as an extension for the ET 250 trainer.
  The photovoltaic DC current from ET 250 is fed to the input of ET 250.01A via a connection cable. Inside ET 250.01 the DC current passes safety devices and enters the inverter. The inverter transforms the DC  into  AC current. The inverter also  optimizes voltage and current to ensure that the photovoltaivc modules produce maximum possible power.
  The inverter output provides an AC voltage with appropriate level and frequency to enable feeding into the mains grid. The amount of fed in electricity is captured by a modern two way electricity meter.   

  Comparing electrical power of the DC input and the AC output enables determination of the inverter efficiency. The dependence of the inverter efficiency on the total electrical power  can be measured in further experiments.
  The well-structured instructional material sets out the basic principles and provides a step-by-step guide through the experiments.