Applications

Solar energy is the cleanest and most abundant renewable energy source available. Solar photovoltaic (PV) cells or panels are the devices to convert solar energy into electricity. Intensive development and large scale solar panel production has started since this new millennium. Global solar PV capacity has reached 494.3GW in 2018 and is expected to grow by over 1 TW between 2019 and 2030(Source: GlobalData Power Database). Most of the capacity addition during this period is estimated to come from China, India and other Asia-Pacific countries. With the rapid grow of installed capacity and technology improvement, the average capital cost of setting up solar PV reduces significantly , but still varies widely from country to country. The decreasing production cost and government schemes are resulting in a decreased average system price of solar PV. The global average capital cost of solar PV plants was $4,162/kilowatt (KW) in 2010, reducing to $1,240/kW in 2018, and is estimated to fall further based on cost estimates in several countries and reach $997 by 2030. The figure below shows the average system price trend of global Solar PV and the top five solar PV countries between 2010 and 2018.

Solar PV Market, global, average cost of key countries and global ($/KW), 2010–2018 (Source: GlobalData)

To maintain competitive, PV and power system manufacturers are continuously looking for new technologies. Power conversion efficiency and Inverter weight / size and material cost all are the aspects a design needs to count in. Solar converter’s power and voltage levels vary based on applications. Residential applications are mostly below 10kW, and commercial commonly range between 10kW and 70kW. Utility-scale power plants are above 70kW. Currently most power plants still use 1000V maximum bus voltage, but more recently developed large solar farms have started to increase PV voltage to 1500V from 1000V. Higher voltage can reduce semiconductor and copper losses and further improve power system efficiency. For 1500V bus voltage, 3-level boost and inverter topologies become the only valid solution with 1200V switching devices.

SiC diodes have been widely used in PV boost converter design, and SiC MOSFETs have been used in many high-performance inverter development. The following are two topology examples used in PV inverter design.

60kW Inverter with TO-247 SiC MOSFET Solution

1500V 150kW Inverter with TO-247 SiC MOSFET and IV1E SiC Module Solution IVCT has developed a 20kW interleaved boost converter to demonstrate SiC diode and MOSFET performance. The converter uses four 80mOhm 1200V IV1Q12080T4 MOSFTEs and four 10A 1200V IV1D12010T3 diodes. At 65kHz, the converter achieves 99.4% efficiency with 600V input and 800V output. The MOSFETs are driven by SiC MOSFET driver IVCR1401. The waveforms below show clean Vds rising and falling edges.