If you haven’t read Part #1 of this 2-part series you probably should.
< click here to read Part #1 >
My Protection Strategy –
So how do I protect my off-grid home?
First off…I place a more likely chance that I will suffer a lightening strike than an EMP. However, I don’t discount the occurrence of an EMP strike on the continental US, and that has the potential to affect our home. Remember I am off-grid so I don’t have thousands of miles of electrical transmission lines attached to my house. That my friend greatly reduces my exposure to an incoming EMP surge.
All that being said I take some basic precautions first…
- My PVs (solar panels) all have aluminum frames, all those frames are attache to an earth ground system. The earth ground system includes:
- A single continuous 8AWG bare copper wire connected to each panel of 3 PVs in the string via a lay-in grounding lug.
- The 8AWG bare copper wire from each string is connected to a 6AWG bare copper wire handling the array that contain 2 strings each.
- The two main arrays (#2 & #3) are connected via 6AWG bare copper wire to an earth ground that consists of three 8’ copper clad rods driven in the ground 10’ apart bonded with 6AWG bare copper. Note1: the arrays are approximately 50’ apart and the 6AWG bare copper wire connecting the two arrays are buried 12” in the ground between the two arrays. Note2: the third array is grounded separately to its own earth ground that is also the house system earth ground. Again, it consists of three 8’ copper clad rods driven in the ground 10’ apart bonded with 6AWG bare copper.
- Each array also has a 40ka surge protector in the EcoWorthy combiner box. That surge protector is connected to the 6AWG array ground wire. The combiner box is a Chinese manufacturer and I don’t know if it will work or not when the times comes. The SPD was included with the boxes when I bought them.
- This gives two types of surge protection; 1) any energy absorbed through the PV metal frames is directed into the ground, 2) any energy absorbed into the PV wiring is directed to the external combiner box’s SPD and that energy is directed into the ground.
- The utility room that houses the solar/electrical/electronic equipment has a metal roof and foil backed OSB on the side walls. I have no idea whatsoever if this provides any protection. Some folks think so, others don’t. I don’t count on it.
- Inside the utility room the incoming PV power lines come into separate array disconnect boxes. Each disconnect box has a Midnite Solar MNSPD-300-DC (80ka) installed.
I consider this to be my lightening strike/surge protection (E2 & E3); 1) good grounding, 2) a 40ka SPD, and 3) an 80ka SPD. But that stills leaves out the EMP E1 power surge. To address that issue you have to go downstream of my system.
Downstream of the array disconnect boxes I have a combiner box that combines arrays into a circuit breakers that also acts as disconnects. that is located just before my charge controllers. Arrays #1 & #3 go into my charge controller #1, and array #2 goes into my charge controller #2. For the E1 surge I have an EMPShield model Dual-DC-90-120-W. Each charge controller has its own protection via this EMPShield unit since it is a “dual” unit. And yes, the EMPShield unit also provides E2 & E3 protection.
And how good is the EMPShield? Well, that is hard to say. Remember, we have no definitive idea if a device works, or not, until an event occurs. But, the documentation on the EMPShield device, along with the advertised testing, assures that it will protect against E1, E2, & E3 power surges. So that combination of surge protectors protects against surges coming into the system from the outside via the DC side of my off-grid solar system.
Now let’s talk the AC side of the system…I also have a Midnite Solar MNSPD-300-AC installed in my main breaker panel. That is intended to protect power surges getting into the system via house wiring. Yup, that means every single inch of wire in the house is a potential “antenna” for power surges. And yes, that means I am only protected against E2 & E3 surges from the AC side of the system. It is my intention that as my research continues and I become 100% convinced of EMPShield products I will install one of their AC units in the main breaker panel and move the Midnite Solar SPD to the inverter/generator transfer switch.
And if you are wondering…I have no problems with an Siemens FS140 (FirstSurge) being used as a substitute for a Midnite Solar SPD. I use Midnite simply because I found it first and have confidence in it for lightening protection.
How an SPD works –
If you are wondering how a SPD works…well, that is another whole article. But the short version is this…the SPD draws the power surge into itself away from other wiring and equipment and dissipates it through its internal parts. Yeah…call it magic, voodoo, or a modern engineering marvel…but that’s how they are designed to work.
Now, have you asked the question yet…Will all of this work and protect my house full of electronics/electrical equipment, and better yet, will it protect thousands of dollars worth of my solar system gear? If you have an answer let me know!
Yeah, a funny way to say I have no idea if this will all work to save me from an EMP, let alone a lightening strike. But I do know that doing nothing will definitely result in a bunch of burned up and useless equipment.
I will write reviews on EMPShield and Midnite products fairly soon. Should you buy now? Well…I did. And doing something is better than doing nothing. Do nothing ensures failure.
If you are interested in buying any of the mentioned products…PLEASE DO 🙂
I am providing links to the equipment below. If you buy one of the Amazon products through my link I will earn about a 1.5% commission. If you buy an EMPShield product I will earn a 15% commission. And if you use the coupon code “ahtrimble” when you buy an EMPShield product on their website you will get $50 off any product.
Any money I earn will go towards a test unit for the AC side of the system. If I earn more than the cost of a test unit then any excess funds will go towards another LifePO4 battery.
Click on the icon below for the MidNite Solar 300vDC unit (for protecting DC voltage equipment)…
Click on the icon below for the MidNite Solar 300vDC unit (for protecting AC voltage equipment)…
Click on the icon below for the Siemens FS140 Whole House Surge Protection…
Click on the EMPShield logo below to buy EMPShield products. Use “ahtrimble” in the coupon code at check out for $50 off any EMPShield product. Hint: If you are buying more than one product then make them separate purchases and use the coupon code for each. If are having trouble deciding which product to buy, then write a comment below and ask for help from me.
Related Articles –
- Protecting your Radio from an EMP: Part #1
- Will we really be hit with an EMP? (part #1)
- Threats, Risk, Matrix, Mitigation: Introduction
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