Solar iBeacons

We previously supplied solar beacons. These are beacons with a rechargeable battery topped up via a solar cell.

Solar iBeacon
Solar Beacon

Solar beacon’s weren’t popular and all the models we supplied are no longer manufactured. Some specialist solar beacon companies, whose models we didn’t supply, have also stopped selling beacons. So what happened?

Solar beacons seemed attractive in that they offered the prospect of not needing to change batteries. They weren’t that much more expensive so price wasn’t the reason for poor takeup. Instead, we believe these were the reasons:

  • Solar beacons were always the dumbest of beacons. The features in advanced beacons, such as sensors and advanced settings, never made their way to solar beacons. If you needed these features then the solar beacon wasn’t suitable.
  • While you didn’t need to change the battery because it was flat, the rechargeable battery still had an inherent lifetime of about 10 years. Given that some beacons’ batteries can last up to 5 years, the solar advantage wasn’t that great. Replacement batteries also cost considerably more than non-rechargeable.
  • Solar beacons with glass solar cells were much more fragile causing them to be more likely to be damaged in transit and use. The solar cell also needed to be kept clean which was a problem in some situations.
  • The rechargeable batteries in beacons tended to be LIR2032. Lithium rechargeable batteries suffer from non-use and once flat cannot be used. Beacons in storage required their batteries to be replaced.

In summary, solar beacons have too many problems that, on balance, outweighed what was a less than expected increase in battery life. For next generation self-powered beacons look to Wiliot who power beacons via energy harvesting. Instead of batteries, they use supercapacitors but even these have limited life.

New Wafer Thin Nordic nRF51 SoC

Nordic, the manufacturer of the System on a Chip (SoC) found in most beacons has announced that an ultra thin version will be available from American Semiconductor.

The AS_NRF51 Flex-BLE (pdf) is an ultra-thin version of Nordic’s nRF51822 SoC wafer-level CSP (WL-CSP), employing American Semiconductor’s ‘FleX™ Semiconductor-on-Polymer™’ (FleX SoP) process to reduce package size to approximately 35µm—roughly half the thickness of a human hair.

The largest component of beacons and Bluetooth sensors is usually the battery rather than the SoC. However, the Flex-BLE version will be especially suited to energy harvested and solar solutions where it will be possible to create very thin beacons that can be invisibly manufactured into products or their packaging.

New Solar Powered Beacon

We now have a few samples of the new TON9218 solar powered beacon available. The large 6.5cm x 9.6cm solar panel keeps the on-board rechargeable LIR2032 battery charged using only normal indoor lighting. Even with weak light, the solar panel generates about 100uA that’s 5x the average current consumption. Hence, with the use of the rechargeable LIR2032 battery as backup, this beacon can work almost forever.

ton9218_smaller

As with the other Iotton models, the beacon has an internal timer and uses the Dialog DA14580 that provides 2x to 3x battery life of Nordic nrf51822 based beacons and up to x6 the battery life of TI CC254x based-beacons.