Solar Battery Charger using Rohm SiC Power Devices

By Mike Donnelly - Principal Engineer at Siemens Digital Industries Software.

This design shows a 1000V, 4760 Watt solar power battery charging system that uses Silicon Carbide (SiC) power devices from Rohm Semiconductor. Under nominal conditions of full irradiance (1000 W/sqr-meter) on the panels and a 250V Battery as the load, the power stage of the design achieves a > 99% step-down conversion efficiency. This is shown as the steady-state (or final settled) value in the waveform display on the right, which shows the battery input power divided by the output power from the solar panels.

While the solar panels and the power stage device models represent real components, the battery and control-block/logic functions are generic behavioural elements, intended only to provide a reasonable operating context for the power stage. In particular, this system is set up to assess maximum power point operation under various source and loading conditions.

The following design can be used to identify the maximum power point load current for just the solar panel, for any user-defined solar irradiance level: https://explore.partquest.com/groups/renewable-energy/designs/solar-panel-load-test-maximum-power 

Once that current has been found, it can be used as the target control input (i.e. the panel current command) in this design. Then the efficiency, battery charging current level and other performance metrics can be determined for that operating condition.

Please first login to DesignSpark Circuit Simulator (opens in new tab), before trying to edit the design below.

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Do you have questions on the above? Ask in the comments section below and Mike is here to help!