Pre-print of article presented for publication in the Proceedings of the 46th IEEE PVSC, Chicago, USA, June 2019 Abstract — The Swiss start-up Insolight aims to be the first company to commercialize a high-efficiency III-V based low profile micro-CPV product that uses planar micro-tracking to eliminate the need for a tilting solar tracker, allowing rooftop mounting using typical flat-plate hardware, as well diffuse light capture using low cost Si solar cells which cover the area of the back plane not taken up by III-V solar cells. The IES-UPM has made an initial performance evaluation of a 0.1m2 prototype. We show that the integrated planar tracking can reach 55° AOI, show CSTC efficiency near to 30% for III-V output, and demonstrate the diffuse capture and planar tracking capability in a multi-week test campaign at our test site in Madrid. This preprint was uploaded before review by IEEE. The post-print is now available and may be viewed in Open Access at the UPM Open Access Repository (oa.upm.es/57352/). No changes to the text were made between the pre- and post- print versions.