Introducing the high-level photovoltaic simulator PVS from Spitzenberger & Spies.
The amount of generated energy of a solar panel field (and therefore the profitable efficiency) mainly depends on varying weather conditions such as cloudiness and adverse weather situations. To achieve the maximum energy rate at heavily varying irradiation, modern intelligent solar inverters are used. The overall efficiency of solar inverters is tested according to IEC/EN 50530. Compliance testing requires powerful voltage and current sources, together with analyser units operating in excellent harmony.
The testing of modern solar inverters requires three main functions of the testing equipment:
1. Simulation of solar panels for testing solar inverters according to IEC/EN 50530
2. Generation of typical loads for the anti-islanding tests according to IEC/EN 62116
3. Simulation of the connected grid
Grid-connected photovoltaic systems feed the generated energy into the power distribution grid network, and the amount of power fed into the grid defines the profitability of the whole solar site. The IEC/EN 50530 describes in detail the necessary calculation formulae and testing routines to evaluate the overall efficiency of solar inverters.
Solar inverters must be designed to be able to deal with many different operating conditions. Intensive testing during the development process of inverters as well as during their production is requested.
In the future, a new type of inverter – the micro-inverter – will conquer the market. These micro-inverters are designed to be placed directly at the solar panel, and will operate at much lower voltages and lower power ranges.
As a good strategy for a complete test of solar inverters’ three main tasks have to be carried out:
Simulation of a solar generator and operating the inverter in the MPP (maximum power point), testing of the MPP tracking function, evaluation and calculation of the overall efficiency
Simulation of varying load conditions and different disturbances like transients, harmonics, ripple, Cos Phi, etc.
Simulation of the connection to the public grid during normal operating conditions as well as during irregular conditions such as during voltage interruptions, variations and drops
Simulation of the energy generation
The generated energy of a solar site varies depending of the intensity of the solar irradiation, level of cloudiness or shading, as well as the ambient temperature and pollution of the panel surface. The conversion of the panel-power through the solar inverter should be carried out in the Maximum Power Point (MPP).
To convert the maximum available energy generated by the solar panels, many inverters use a MPP tracking algorithm. This algorithm changes the load condition of the inverter so that the panel field always sees an ideal load and can transfer the maximum available energy.
