Catweazle wrote: ↑Fri Apr 19, 2024 7:57 pm
I'd be very interested, it's been worrying me that my whole solar system could be rendered useless by emp. Most electronics are duplicated, with the spares inside metal tins, inside metal filing cabinets and inside a metal shipping container, but that's not practical for the panels. If it's just the blocking diodes that will fail I can fit replacements. But if the panel has self fails it's more serious.
Faraday bags and wallets for blocking signals to and from phones, tablets or laptops are available on ebay or Amazon. Note that the metallised linings can wear with a lot of use, causing the bag to lose its effectiveness. First, assuming that the metal containers you're using are for use as Faraday enclosures, such containers need to be virtually watertight to be truly effective. Faraday bags can be made at home using kitchen aluminium foil with polythene. Note that the adhesive on the vast majority of aluminium tape has non-conductive adhesive. This can affect the integrity of a home - made Faraday bag or enclosure. Any boxes or dustbins used need to have conductive gaskets for lids. Metal lidded tins can be used, but these usually have paint or clear varnish where the lid is fitted. This needs to be removed by careful sanding to maximise the effectiveness of the enclosure. All lids need to be very close fitting. Faraday enclosures can be "nested" one inside the other to maximise protection. Any electronic kit with metal on the casing needs to be insulated from any metal of the faraday enclosure. Larger enclosures can be lined with non - conductive material.
Note that more than one EMP can happen, so be aware of this possibility when getting kit out of Faraday enclosures after a strike!
Surges and voltage spikes can also happen as a result of poor connections causing arcing and power outages. It's best to check all screw-down connections such as those on charge controllers and mains plugs for tightmess and cleanness. Tightening such a connection for the first time tends to compress the wire, possibly resulting in a poor connection developing over time. I go over these a second time when assembling them. The steps suggested below will help mitigate the effects of power outages.
What can and cannot be damaged in an EMP burst or CME depends on its intensity. However, it's generally thought that solar panels that are not connected may escape destruction if not connected up. If connected up ,the voltages induced in the wiring may or may not damage the solar cells or their diodes. It's probable that the charge controller will be damaged. As you've gone to so much trouble generally, it's worth considering the purchase of spare diodes. They're relatively inexpensive and available on eBay. It's worth getting diodes rated at least 200v and at the current rating of those in your solar panel(s).
For the purposes of this discussion, although CME, EMP and lightning have different properties and effects, basically they all generate power surges and voltage spikes. These can be tackled more or less simultaneously using similar methods. There are a few basic accessible component types that can be used to give limited protection to electronic kit:
Metal Oxide Varistors (MOV's). Connect across (in parallel with) device to be protected.
Transient Supressor Diodes (TVS diodes) - use bidirectional types as they're non - polarised and can be connected either way round). Connect across (in parallel with) device to be protected.
Gas Discharge Tubes (GDS tubes). Connect across (in parallel with) device to be protected.
Clip - on ferrites or chokes, which form inductors. These can be clipped around any cables as required and are the clylindrical lump found on many PC monitor and other cables. A relatively mild effect, but also offer some protection against radio frequency interference (RFI) if used judiciously. Clip around BOTH cables for DC, and all three wires for mains. Effectively, the inductor is wired in line (in series).
These are available quite cheaply from eBay and other sources, and are small and easy to use.
This will take one a fair way up the curve of diminishing returns and give basic protection against most overvoltage events. To protect against a full-on EMP is another story.
There is also selenium technology, but this is rather specialised and expensive.
For those who can solder, these components can be added as convenient. Otherwise, terminal blocks can be used, such as those on charge controllers. This will be harder to apply to solar generators as everything is built in.
To gloss over the details, I've connected 3 TVS diodes straight across the lithium battery to give it some protection, and a couple of clip on inductors followed by a MOV after the main system fuse but before the charge controller. I plan to connect a MOV on the solar panel side of the charge controller and a GDS inside the box where the diodes are on the solar panels if there's room. MOV's can get hot in use if there are many surges. In other words:
BATTERY WITH TVS> MAIN SYSTEM FUSE> INDUCTOR> MOV> CHARGE CONTROLLER WITH MOV> SOLAR PANEL WITH GDS.
Have you tried a small roofing firm ?
