Solar cells power up portable electronics

A new range of high efficiency solar cell arrays and cards are designed specifically for charging batteries in portable electronic devices.

A new range of high efficiency solar cell arrays and cards are designed specifically for charging batteries in portable electronic devices.

With an efficiency of over 17%, the solar PV arrays enable the ability to extend run time even in "low light" conditions and increase battery run time and life in a small footprint, which can be easily accommodated in the design of portable products.

The PV-Array and PV-Card families each comprise multiple series/parallel-connected solar cells, which provide a range of output voltages at currents from 30 to 100mA.

The solar cells use Ixys' proprietary monocrystalline, highly efficient Ixolar cell technology.

There are four different cell areas available: 120, 240, 360 and 480mm2.

The XOA17-12-04 PV-Array is the smallest commercially available product with four Ixolar solar cells connected in series and mounted on a FR-4 printed circuit board.

With an area of 480mm2, this array generates typically 72mW at 2.4V open circuit voltage making it ideal for portable electronic instruments, remote sensors, military and civilian portable wireless communication, consumer products and as emergency backup battery power.

The PV-Card product family is constructed using Ixys' proprietary DCB (direct copper bonded) ceramic as the substrate for the solar cells.

The DCB substrates provide improved thermal conductivity and better reliability due to similar thermal expansion coefficients.

In addition, DCB substrates can be patterned to mount additional chips with the solar cells such as a Schottky diode to prevent discharging of batteries during night time.

PV-Cards are ideal for higher power outdoor concentrator applications such as for battery backup in commercial and telecomms equipment.

The sunlight is concentrated with a Fresnel lens on top of the PV-Card.

The output current can be amplified by the factor of more than three depending on the lens system.

The DCB substrate enables heat generated under these conditions to be easily dissipated by attaching the PV-Card to a heatsink.

The PV-Cards available now are: the XOA17-12-14D, capable of 225mW at 8.4V; and the XOA17-36-10DS, with up to 500mW.

The XOA17-36-10DS contains a Schottky diode with a forward voltage drop of only 0.3V and has two strings of five series-connected XOD17-36 cells.

These two strings can be either connected in series to generate 6.2V or in parallel.

The XOA17-12-14D has a size of 58 x 48mm and the XOA17-36-10DS has a size of 106.7 x 46.7mm.

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