Solar Powered Bluetooth Bluetooth Beacons

While we previously sold solar powered Bluetooth beacons, we have been reflecting on why they never gained widespread adoption.

Solar iBeacon

Cost and Complexity: Solar panels and related hardware add to the cost and complexity of Bluetooth beacons. This makes them more expensive to produce compared to battery-powered alternatives.

Reliance on a Rechargeable Battery: In order to keep working under temporary poor lighting, a rechargeable battery can be included in the design. This battery, itself, has a limited physical lifetime and will eventually need replacing.

Reliability: Solar power is dependent on environmental conditions. Inconsistent sunlight exposure can affect the reliability and performance of the beacons, especially in indoor or shaded areas where they might not receive enough light to function properly or to recharge an internal rechargeable battery.

Limited Use Cases: The primary use case for Bluetooth beacons is in locations where they can consistently operate without frequent maintenance. Battery-powered beacons, with their long-lasting, 5 yr+, batteries, already serve this need effectively. Modern Bluetooth beacons are designed to be highly energy-efficient, lasting a long time on a single battery. This diminishes the need for an additional/alternative power source like solar energy.

Market Demand: The demand for solar-powered solutions in the Bluetooth beacon market was always low. Businesses prefer established and reliable battery-powered beacons, reducing the incentive for companies to invest in solar-powered alternatives.

These factors combined to limit the appeal and practicality of solar-powered Bluetooth beacons, leading to their limited adoption in the market.

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.