Navigation for and tracking of humans within a building usu- ally implies significant infrastructure investment and devices are usually too high in weight and volume to be integrated into garments. We propose a system that relies on existing infrastructure (so requires little infrastructure investment) and is based on a sensor that is low cost, low weight, low volume and can be manufactured to have similar characteristics to everyday clothing (flexible, range of colours). This proposed solution is based on solar modules. This paper inves- tigates their theoretical and practical characteristics in a simplified sce- nario. Two models based on theory and on experimental results (empir- ical model) are developed and validated. First distance estimations indicate that an empirical model for a par- ticular scenario achieves an accuracy of 18cm with a confidence of 83%.