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Forum Index : Solar : Lightning and Grid Connections.
| Author | Message | ||||
| neil0mac Senior Member  Joined: 26/12/2009 Location: AustraliaPosts: 210 |
What measures can be taken to protect a grid connected solar system from 1 million plus volts? None? |
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| Robb Senior Member Joined: 01/08/2007 Location: AustraliaPosts: 221 |
Big MOVs, fusable links and spark gaps. |
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KarlJ Guru  Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Simple to put a lightning rod on the other side of the house with a cable to the ground. Small cable, needs replacing every time its struck, big cable costs a fortune and may still need to be replaced as we are talking a fantastic amount of energy. I was really lucky, got struck by lightning when I was flying model aeroplanes at Kilkunda (?spelling near Phillip island on the mainland) came down the transmitter antenna and then to the ground, so other than an almighty fright I was OK, transmitter funnily enough was OK too. Luck favours the well prepared |
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Loomberah Regular Member  Joined: 11/06/2008 Location: AustraliaPosts: 43 |
Its a problem with stand-alone systems too, solar panels on the roof and especially WTGs on tall metal towers. My roof got sruck on Thursday, twice in about 1/4 second. Fortunately the panels and WTG are nowhere near the house, and everything survived unscathed, although I had unplugged all computers, TV etc beforehand. Gordon Loomberah weather +solar&UV, astronomy, photography, organic farm |
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MacGyver Guru Joined: 12/05/2009 Location: United StatesPosts: 1329 |
Just a quick thought: Is there any "usable" electricity in a lightning strike? I've seen it set a fire as well as split a tree. The fire was small (to start with) and I assume the tree split apart due to moisture inside boiling and turning to flash steam, its expansion responsible for the splitting (just a guess). Would it be worth trying to capture a strike (I don't know how in the world that could be done, mind you) or is that a silly question? Hey, while I'm on the subject of goofy questions, does anyone know if the pressure inside the tip of a funnel cloud (tornado) is low or high? I was just curious if the swirling funnel was the same principle as water sucking down a drain and if the pressure difference was due to high pressure on the ground going up or high pressure in the cloud coming down. Just curious. . . . . . Mac Nothing difficult is ever easy! Perhaps better stated in the words of Morgan Freeman, "Where there is no struggle, there is no progress!" Copeville, Texas |
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Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
MacGyver; 1) Is there any "usable" electricity in a lightning strike? MILLIONS of WATTS. 2) Would it be worth trying to capture a strike (I don't know how in the world that could be done, mind you) or is that a silly question? Not silly Remember Ben? His Kite and key and Leiden Jars? All you need is lots of Kites,Keys,and Jars.! A high Hill or stormy mountain could replace the Kite, A copper Grid with a set of multiple Diodes to connect to earth ground through enormous Capacitors. This one way circuit will not allow the return stroke and will maintain a high voltage field on the grid which will attract another strike. power can be taken from the capacitor until the next storm or the trapped energy is depleted. Where are those electrical engineer's when you need them?? 3) I was just curious if the swirling funnel was the same principle as water sucking down a drain and if the pressure difference was due to high pressure on the ground going up or high pressure in the cloud coming down. You are very close to Right. Pressure is very low in a funnel Cloud. The funnel begins to form when a Mass of frigid air gets trapped inside a greater mass of warm humid air. "Rapid condensation with in the air mass" starts the sucking sound as air rushes in to replace the water vapor. Time has proven that I am blind to the Obvious, some of the above may be True? |
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| Greenbelt Guru Joined: 11/01/2009 Location: United StatesPosts: 566 |
MacGyver, I was checking out the internet for power in a lightning strike - bolt, Several links say a 100 watt light bulb will burn for 3 months off a bolt of lightning. I figured this at 2.4 kilowatt hr.'s per day times 90 Days. = 216 kilowatt hr's The web sites claim a lightning bolt voltage is 300,000 + volts at 10-20 thousand amps = 3,000,000,000 watts, The duration of the power stroke is variable as I have seen the forked lightning channels link up and release energy to the main cursor sometimes requiring seconds in multiple strikes to equalize the charge. 3600 seconds in an hour. using 1/2 second of power at 3 billion watts = 3,000,000,000 divided by (2x 3600seconds) = 416666 watt hr's / 1000 = 416 KW.hr's Time has proven that I am blind to the Obvious, some of the above may be True? |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
I dont know what makes the tree split in half but it might also have something to do with the gas within the wood to. I have cut up a tree that was hit by lightning for fire wood and the wood would not burn worth crap. It just smoldered like a wet mop. Even green wood will burn with enough fire under it, but the wood struck by lightning refused to catch fire. Pete. Sometimes it just works |
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| neil0mac Senior Member Joined: 26/12/2009 Location: AustraliaPosts: 210 |
From memory (Wood technology at Uni) the lightning turns moisture in the sap to steam resulting in a rapid increase in volume. Maybe it has a much higher ignition point? (You can burn the carbon content out of mild steel at around 1600 Deg. C. Makes a pretty sparkler!) |
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Don B Senior Member Joined: 27/09/2008 Location: AustraliaPosts: 190 |
The old saying that lightning never strikes the same place twice is absolutely true. The reason that it is true is that, after the first strike, the same place isn't there any more. There is a truly enormous amount of energy in a lightning bolt. Unfortunately, it is all over so quickly that there is virtually nothing that can be done to make any practical use of it (Dr Frankenstein excluded). Luckily, in most instances, there are a number of simultaneous parallel paths that the lightning will travel through which might save some of those paths from the worst effects of this energy surge. Effective earthing does help but, unfortunately, the earth has very high resistivity compared with anything metallic. The real problem for both equipment and people arises from the potential differences that can develop between different metallic paths as the lightning finds its way into the general earth mass. The most useful lightning protection is to have everything metallic electrically bonded, so that the inevitable voltage rise does not result in significant potential differences between things that might result in a side flash. The earth system in a household does help for this where equipment does have an actual earth wire. There is also the Faraday cage effect, which says that anything inside a metal enclosure (eg a car) will rise to the same potential as the enclosure, and will be unaffected. Unfortunately, while bonding and Faraday cages might protect electronics from the worst effects of voltage differences, the high currents that flow associated with a lightning strike will induce currents in any adjacent conductors. If all of the connecting wires to your equipment have been disconnected, you might have a better chance of avoiding damage, but there will still be currents (and associated voltages) induced within the equipment itself. Really, it is just a lottery as to whether well protected things will be damaged or not by a lightning strike. Regards Don B |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
From what i had seen somewhere (fact or mith) more people get struck by lightning playing golf than any other activity. So perhaps one can make a fortune with ground earthed golf clubs or a mobile Faraday cage. ****The must have accessory for the golfer!!!!**** A friend of a friend (yes i know its a bit like a cousin of a cousin )was struck by lightning playing golf (he survived) and afterwards his dog dis-owned him and his wife left him, all because he always smelt strange afterwards. It was said sitting next to him at a bar his odour was noticeable. I would guess it must fry the sole or hole of ones body. Never been struck to know?...Kinda happy with that!! Pete. Sometimes it just works |
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