Here are the build details and some photos from a DIY ‘Build a Solar Phone Charger’ workshop I ran at Nottingham Hackspace.
There were six participants and they all built a small phone charger which runs from solar power.
Full design details and instructions are available to download here.
The end result was a small solar array (total of around 1Wp) comprised of four smaller solar photovoltaic panels.
The design needed to recharge high-current smart phones. With the solar array only 1Wp this would not supply enough current to get the phone to charge, hence we needed to use a couple of rechargeable AA batteries. These are trickle charged by the solar cells, with a diode to stop any drain at night-time.
A DC-DC converter with a USB output steps-up the battery/solar panel voltage (around 3.4V maximum) to the 5V required to charge a phone. A small switch is used to stop the converter draining the battery when nothing is plugged in.
These had come from a previous project, hence they were second hand, but all of them were tested and working well.
The participants both took home a working solar phone charger, just in case they need to survive the apocalypse.
Here are the instructions for the kit. This was the first time I had run this workshop, so there were a few adjustments including:
- Check the orientation of the laser cut pieces of wood – they only fit together with the DC/DC converter one way
- Soldering the 2 x AA battery holder was a pain – the heat from the soldering loosened the connections which needed to be bent back.
Here is the design file for the laser cut parts. It is also available as a .dxf here.