Repower Your Raspberry Pi
Better Safe than Sorry
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Solar-powered projects sometimes require a parallel power supply to bridge periods of darkness. There are a number of technical pitfalls you need to avoid.
There are good reasons for using multiple sources to supply power to a Raspberry Pi. Of course, there are a few things to think about, and some electrical engineering wizardry is unavoidable. To understand how some circuits work, you will also need to familiarize yourself with the characteristic curves of a couple of components.
This article takes a look at a solar-powered weather station that repeatedly fails during periods of bad weather. You can work around this issue with a simple emergency power supply that kicks in whenever the solar module fails to deliver enough power. My first idea was to connect the voltage sources in parallel, but it is important to remember that the intent is to use them alternately. If the solar-charged battery is exhausted, the device draws its power from a power supply unit. As soon as the sun reappears, the solar panel kicks in again. This is not a parallel connection in the strict sense, but a kind of either/or situation.
Background
When you connect voltage sources in parallel, it is important to ensure that the voltages and internal resistances of the two sources are absolutely identical. If this is not the case, compensating currents will flow between the voltage sources, causing both of them to burn out. This may need some explanation.
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