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Solar PV- Lightning Protection

Last Post 13 Dec 2010 12:45 PM by Dana1. 4 Replies.

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chrisbiker User is Offline

New Member

Posts:97

05 Nov 2010 02:44 PM
I just had a 10 Kw grid tied solar PV system installed on our house in SE Pa. It's located on the upper roof on a normal 2 story home. The installer put in a heavy duty ground cable (not sure AWG) that connects to each panel and all the mounting rails with approved grounding connectors. This ground wire and all the DC wires (six strings) were pulled through metal conduit down to the basement. That ground ties to all the disconnects and the two inverters in the basement and then is tied into the main electrical panel ground. It all looks well done and was blessed by the electrical inspector. Questions: Is there a high risk of lighting strike damage to the system? Is there some additional grounding or other devices that will mitigate this? What are others usually doing? Are arrestors needed on the DC and AC lines adjacent to the inverters? Perhaps what I have now is perfectly fine... I am looking for some common sense on this topic that will help me understand what I am up against and if it's prudent to pursue adding some addional protection. Thanks for any and all coments. Chris

judas

New Member

Posts:23

01 Dec 2010 11:15 AM
old school? put a copper lightning rod up or a bare coper wire the length of the roof ridge?

paulwood09 User is Offline

New Member

Posts:14

10 Dec 2010 10:30 AM
While it is good for an owner interested in a renewable energy source for his home to understand what he can expect from a particular PV panel installation, it is always important to let the professionals handle the design, equipment selection, installation, commissioning etc

<a href="http://www.greentech.ie/"><strong>Renewable energy systems </strong></a> for all your needs

jonr

Senior Member

Posts:5341

10 Dec 2010 09:02 PM
I would look up the frequency of lighting strikes in your area. If the statistics concern you, then I agree with judas - you want something that will keep the lightning outside of the house, not bring it in (ie, lightning rod + external ground strap). I would also use surge protectors on any AC lines from the utility you might have.

Dana1

Senior Member

Posts:6991

13 Dec 2010 12:45 PM
A surge protector buys you almost no protection from any lighting-related damage (but they are still a good idea to protect from other powerline transmitted switching spikes, etc.) Lighting risk is very location-specific. On a high exposed ridge your risk is much lower than in the valley bottoms, etc., but immunity just isn't in the cards (particularly from secondary induced-effects, even when the direct hit risk is near-zero.) All electronic controls are susceptible, as are the panels themselves. The measures already installed are probably "reasonable" for average risks, and there's a rapidly declining cost/benefit to go a lot further. (It's probably cheaper/better to spread the financial risk with that newfangled device called "insurance".)