socalledunitedstates:

Libre Solar: open-source renewable energy hardware

Clean energy from renewable sources should be accessible for
everyone. Otherwise, how should we ever manage to limit global warming?

Unfortunately, the energy supply of most countries is still
controlled by some few large fossil fuel companies which try everything
to keep the status quo. Their large coal and nuclear power plants should
be replaced by millions of small, decentralized renewable energy
generators.

Our mission is to help reclaiming the energy supply using affordable renewable energy solutions based on open source hardware.

The primary focus of Libre Solar is solar electricity generation and
storage. Accordingly, the initial open source hardware projects are a
MPPT charge controller and a battery management system for Lithium ion
batteries.

Read more…

These would be perfect for a personal solar system!