This is pretty interesting. An libre open-source UV metering system. It only meters ambient UV light levels, it does not provide you with an image. Hence it saves greatly on cost, in other words. On the other hand, it is still a fairly expensive gadget to purchase in addition to a Raspberry Pi Zero.
20170430/https://www.open-electronics.org/save-your-skin-with-this-open-source-uv-index-detector/
20170430/https://store.open-electronics.org/Module-UV-sensor-ML8511
New Raspberry Pi rival from Huawei? Only a rival if you think $240 is a rival price-point.
20170430/https://www.open-electronics.org/the-brand-new-raspberry-pi-rival-huawei-hikey-960/
20170430/http://www.96boards.org/product/hikey960/