in my blog I began a new series of posts. These posts are about how to supply your arduino project with solar power. Now the first post is online. It shows the basics of a offgrid PV system: what components you need and how they work together.
If interested look at:
This series will be continued with a in-depth look at all the components. It will also be about how to choose the right components (e. g. how much power your PV panel should have).
hope it helps