EYE on NPI - TDK BCS Series Low Illumination Film Solar Cells

This week's EYE ON NPI is so flexible, it's thinking of joining the Rockettes (https://www.rockettes.com/christmas/)! It's TDK's BCS Series Low Illumination Film Solar Cells that are designed for direct integration of products, particularly wearables or credit card size and thickness electronic components. This amorphous panel comes with 6 cells, each about 0.4V open-circuit, for a total of about 2.6V output and 30mA. The nifty part about this panel is just how incredibly thin it is - only 0.2mm which means it can be bonded onto almost any surface or device. And unlike most panels that are made of monocrystalline cells, it is ultra flexible and will not crack or break. TDK's BCS series are thin, lightweight, and flexible solar cells offering high power generation efficiency under fluorescent and LED light sources. The cells are made of amorphous silicon film substrate, and designs can be customized according to various shapes and applications. Because BCS series solar cells offer output stability in low and dim light, they are suitable for use in products used indoors. Additional benefits of solar cells include cost reduction in electrical wiring and battery replacement. When used in combination with a primary battery, solar cells can extend battery life and usage time of rechargeable devices. BCS series solar cells can be used in applications such as watches, wearables, beacons, wireless sensor nodes and other IoT power supply applications, smart cards and locks, and more. Compared to many other ultra-low power source harvesting techniques (https://en.wikipedia.org/wiki/Energy_harvesting) like vibration/piezoelectric or heat, solar is very efficient, very small and very easy to use. Amorphous cells are a great option for folks who want to have indoor-powered electronics without hassle. Simply connect the two terminals to you circuitry plus and minus: when there's ambient light, you'll get voltage output. These panels may look familiar if you've ever had a solar-powered calculator (https://en.wikipedia.org/wiki/Solar-powered_calculator) - often times you'd have to hold these up to a lamp to get them 'kick-started'. Those pocket calculators with LCDs are a great example of ultra-low current draw electronics that could run off of a tiny cell, we're talking under a milliamp here. That's something to keep in mind when integrating panels, they produce about 1/10th of the power folks think they do! The biggest challenge that folks have with implementing solar panels is that they don't really act like a true voltage source or current source: they're somewhere in the middle, like a negative diode. With solar panels, the voltage and current vary constantly depending on sunlight available. They are unstable! That instability confuses electronics battery chargers, which causes them to do one of two things: rapidly turn on and off as they try to draw more current from the panel than possible and/or draw much less current than they can, to keep the voltage from collapsing. So you've got a few choices for implementing this panel: 1) have electronics that is OK with a widely varying input voltage: about 2V to 5V max, and will brownout safely when light disappears all of a sudden. Then, make sure it uses less than a few mA of current so that it doesn't collapse the IV curve by drawing too much power 2) use a super capacitor or rechargeable battery of some sort, that is trickle charged by the panel. once the voltage on the cap gets to a certain amount, the circuitry can use that to perform whatever calculators or data transfer required. 3) use a smart energy-harvesting chip like the LTC3588 (https://www.digikey.com/en/products/detail/analog-devices-inc/LTC3588EMSE-1-TRPBF/2216345) to manage the load on the panel and either charge a battery or directly power electronics with a cleaner supply than directly powered from the solar cell. Sometimes these chips can even operate as a MPPT charger (https://en.wikipedia.org/wiki/Maximum_power_point_tracking) to get the very max power possible. If you're interested in adding a super-flexible and ultra-thin green power supply to your next design, check out the BCS4430B6 (https://www.digikey.com/short/vwm3z35j) and friends. The TDK BCS Series Low Illumination Film Solar Cells (https://www.digikey.com/short/vwm3z35j) are in stock right now at Digi-Key for immediate shipping! Order now and you will be relaxing in the sun by tomorrow afternoon. See these at Digi-Key at https://www.digikey.com/short/vwm3z35j