Inverter

Stellaris

The Stellaris Digital Inverter (SDI) testbed prototype is an electronic system for converting DC power generated by an array of photovoltaic (PV) panels to line voltage AC for connection to the grid. It is basically a solar inverter with a unique topology. Unlike existing solar power inverters, which convert a single DC input bus to AC, the SDI makes AC by dynamically switching taps in a series-connected string of PV panels. Communications between the main and several ladder modules is facilitated by a CAN bus interface, allowing telemetry and control of all operating parameters. The SDI measures the operating point of each PV panel and is able to optimize panel load on an individual basis, allowing better PV panel utilization. Intrinsically safe override circuitry allows local clamping on any or all PV panels to a very low output voltage. The objective was to provide these functions while decreasing system complexity, DC cable losses, and cost. While the testbed prototype has several extra features designed to ease algorithm and performance research, it demonstrates the relative simplicity of the topology and the effectiveness of the approach while achieving high power and efficiency. Stellaris conceived the patent-pending concept and asked Cooper Perkins to design and fabricate a proof-of-concept prototype of the invention.