I want to use an Arduino as a weather station and I want to put it high up in a tree. It should be independent and powered by solar panels. This is where the problem starts.
Lightning strikes occur pretty often in my area, and I assume the lightning would hit the Arduino and its components before it would hit any other tree.
Is there any way I can prevent the lightning from hitting the Arduino? There is a hut nearby (around 40m) which has lightning protectors on it. In case the lightning hit the Arduino, is there any way to prevent damage to it? I plan to use pretty expensive components and I don't want them to be destroyed.
Best Answer
By the fact you're using an Arduino I suspect your project is not done in a professional framework, but it is some hobby or research project, i.e. something with relatively low budget. Please, correct me if my assumption is wrong, because I'll start from there in my answer.
In these conditions, I fear the answer is no, you cannot protect your weather station from direct lightning strikes, unless you spend much more money than the cost of the entire project.
That's because lightnings are extremely nasty beasts (much more than one could imagine!), and to justify my claim I'll cite some sources from the Internet below.
First of all, for the public at large, a brief introduction to what lightning are by an expert in that subject. And here is a more comprehensive scientific article on the subject.
Let's get a bit more technical and tackle lightning protection: here is "How to Protect Your House and Its Contents from Lightning", a guide for technicians by IEEE. Some excerpts (emphasis mine):
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That guide focuses on household protections, so it is not aimed at your use case. There is this further guide which may be more relevant: Lightning Protection, Grounding, Bonding, Shielding, and Surge Protection Requirements, from the US National Weather Service. It is a rather technical manual on the protection requirements for weather stations. Not a smooth reading, but you'll get a glimpse of the difficulties you face when trying to protect sensitive equipments and installations out on the field. Some excerpts:
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Let's summarize the key points: one big problem is that the lighting strike acts like a current source, not a voltage source (as one may expect): there is some charge that must travel through the objects the bolt meets on its way. Until that charge has traveled to earth and dispersed into the mass of the planet, current will keep flowing, no matter what. To protect things you should provide low-impedance paths to earth for that current, so that only low voltage surge will develop. But that's a hard thing to do: even a meager (for a lighting) 10kA will cause a 10V voltage drop across a 1mΩ (some PCB traces have higher resistance!). That's reasonably safe for a human being, but it's enough to kill sensitive 3.3V or 5V powered ICs instantly!
You may shield a circuit with a Faraday cage, which is an effective countermeasure, but that cage must be massive and of well conductive material, so that such a huge current is presented with 10s of μΩ paths or less! And note that any aperture in the cage can provide paths with higher resistance.
Then there's the problem of the huge EMP (Electro-Magnetic Pulse) generated by the lighting. People think that lightning is static electricity, but that's wrong! The static charges are those on the clouds that are the cause of the lighting. The lighting in itself is a time-varying pulsed current, so it develops harmonics of huge amplitude. Even if you succeeded in shielding your circuit from the conduction currents, there are the induced currents: any aperture in the cage is a path for EM radiation from the EMP, and any PCB trace can act as an antenna inside the cage. Enough energy could be transferred to the circuit and fry it, unless proper countermeasures are taken.
EDIT (after the answer was accepted, to cite an interesting and spot-on source)
I just found this ON semiconductor application note on Transient Overvoltage Protection, which is just on-topic, especially when it describes lightning protection. Some excerpts (emphasis mine):