Modular and mobile photovoltaics on wheels

March 22, 2016 // By Julien Happich
Dutch startup Solar Application Lab has designed a prototype solar e-bicycle that integrates multiple solar panels on its front wheel, enough to recharge the e-bike's battery over the course of the day.

Sporting a 250W front-wheel integrated electrical engine, a 400W 36V 11A battery and 60 mini solar panels which provide the S-bike with an average of 35 to 40Wh per hour during daytime under the fairly clouded Dutch skies, the prototype was proving enough for the startup to secure strong partnerships with well-established bicycle manufacturers.

The first prototype was designed based on mono crystalline cell technology but the company is working in close cooperation with the Delft University of Technology to develop a second prototype based on amorphous silicon, hopefully ready within the next 6 to 12 months.

Although organic flexible photovoltaics are on its radar, the startup sees them as a longer term prospect, knowing that its energy harvesting architecture is cell-technology agnostic and could accommodate any new photovoltaic configuration.

To make the most of each individual panel, the S-bike relies on a patented nano-inverter architecture which the company says makes the cluster of cells more efficient and ensures a stable power output, even under partial shading or at varying light angles.

Having proven the concept, Solar Application Lab hopes to co-develop a solar e-bike with partners from the cycle industry, to whom it would then license the nano-inverter IP.

"In fact, the Solar Cycle is a vehicle for our IP", told us Marc Peters, the company's Founder and Managing Director.

"We couldn't work with existing micro-inverters from the photovoltaics industry, those would have been an overkill for our application. So we had to build our own architecture from discrete components" he explained.

A nano-inverter ASIC could take
Solar Application Lab well beyond the
e-bike market, managing unique solar tile designs.

"Our nano-inverter can work with any type of solar cell in any cluster configuration, on a small scale" he continued. The Solar Cycle is a starter, aimed at the booming e-bike market. If it becomes a success, maybe the company will have the multi-million euros budget to turn its IP into silicon.

"We want to design an ASIC for it, most definitely" said Peters, hinting at the 130 or 90nm nodes, "or maybe two or three product versions to cater for 80 to 90% of the market for small scale modular photovoltaics". For example, derivative products enabled by such an all-silicon nano-inverter could include unique photovoltaic tiles designed to be laid out in clusters of any size.