One surprising aspect of this solar charging system for a cargo bike is its design philosophy, which allows for recharging the e-bike batteries and simultaneously running camping accessories during stops. The maker designed the system as a modular proof of concept, meaning not every component is attached at all times.
This setup functions as a 12V system utilizing an MPPT charge controller. The maker employs a sandwich method for the solar array, featuring one fixed panel combined with smaller panels stored in a slide-out tray for deployment during breaks. The array peaks near 370W, using two 110W foldable panels and smaller units. The system incorporates terminal barrier strips, fuses, power cabling, and external output connectors, all managed by two Victron SmartSolar MPPT charge controllers.
The maker successfully demonstrated that small 12V loads, such as a warming lunchbox or immersion heater, can operate while the primary batteries continue to receive charge. The cargo bike, which is a Riese und Müller Multicharger Longtail, has a battery box containing a 50Ah LiFePO4 battery that accepts about 300W.
However, the maker identified weight and packing volume as major constraints, noting that glass panels proved too heavy compared to the increase in energy they provided. The builder notes that the current setup works differently than originally envisioned, presenting an open question regarding how best to achieve lightweight panel mounting and optimal angles for future iterations!
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