Technology squeezes the most power from solar-cell arrays
By Graham Prophet, Europe Editor -- EDN, January 22, 2009
National Semiconductor plans to introduce the SolarMagic chip technology, which optimizes the power output from solar-cell arrays. The company expects the chip to be useful in the management of battery packs in applications such as EVs (electric vehicles) and HEVs (hybrid EVs).
Solar cells usually connect in series/parallel arrays. Solar radiation may not reach certain cells during certain parts of the day, reducing the available power from the series-connected string. The effect is greater than intuition would indicate: The company’s figures indicate that approximately10% shading—by area—can reduce power by as much as 50%.
The company employs its SolarMagic technology to disconnect the worst-performing cell in a series string and to deliver the maximum available power from the remainder. The technology then takes the reduced power available from that underperforming cell and adds it back—by dc/dc conversion—to the total power from the rest of the array.
In many scenarios, the company says, you can recover more than half of the power loss that the array would exhibit without this technology. The same strategy would be useful in extracting the maximum performance from EV-battery packs. In that situation, one battery cell that discharges more than the others in a series stack exhibits a lower voltage and higher internal resistance, reducing the output of the stack. You can use the same approach to extract all the available charge.
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Solar Magic sounds like smoke and mirrors.
John R Barton - 2009-12-2 13:41:00 PST -
Solar Magic sounds like smoke and mirrors.
John R Barton - 2009-12-2 13:41:00 PST
