Electricity During an Emergency: Solar Power Generation


photo credit: twentyeight

For several months I’ve been exploring different options for generating electricity in a TEOTWAWKI scenario. My initial search revolved mainly around gasoline generators, and I decided that I would get a Honda EU2000i. This is a great unit that can also be converted to accept not only gasoline, but propane and natural gas as well. This makes it a versatile unit worth considering if you have a source for any of these three fuels.

However, the more I thought about it, the more I realized that this was not a good option for my needs. I ultimately decided not to buy the generator for a couple reasons. First, generators are loud. If you are in a crap-hit-the-fan scenario and are using your generator, then you are likely the only one in the area making that much noise. You will stand out and attract unwanted attention very easily. Second, the usefulness of this generator is directly dependent upon the source fuel. When your supply runs out, then the generator becomes a heavy paperweight. You could barter for additional fuel, sure—but in a dire emergency, the general supply of oil-based fuels will likely quickly deplete. Prompted by Wade’s post, I had been considering acquiring a propane tank for long-term emergency use. But even still, the usefulness of this item has a hard limit that acts as a barrier for utility.

Other options

For these reasons, I decided to divert my attention elsewhere. I briefly explored wind generators of various types, but ultimately felt that these weren’t a good option. Most of them are very bulky units made primarily to be affixed to your home or other unit (RV, boat, etc.). So, I began to look into solar power. I was lucky to have access to an acquaintance that answered all of my questions, and helped me determine what would be best for me. Along the way, I discovered a few important items that deserve consideration:

  • We are very spoiled living on the grid. To produce the amount of electricity we consume on a daily basis would, if using alternative energy sources, require a significant investment.
  • Many system solutions do not lend themselves to both integration in your home and portability. Meaning, you either set up solar panels (or a wind generator, or a propane tank, etc.) to feed directly into your home grid, or you instead build a portable system that will not be integrated. A “hybrid” system is possible, though not common. (Who wants to go up onto their roof every time they have to unmount a solar panel to take camping?)
  • A modest investment in solar technology will not produce anywhere near the amount of electricity we regularly use. Thus, a smaller system would likely not be a wise option for integrating into your home, since it would not have much of an impact at all, and thus would not be worth spending the money on integrating.

My system

My decision was to get a portable system that would lend itself to bugging out, camping, or going mobile for whatever reason. Likewise, I could simply leave it in the backyard to be used at home as well. Here are the details on my configuration (recommended and built by an acquaintance of mine here in Utah valley; if interested, he can help you get a system you like as well):

Batteries

Obviously, the first need for any system is one or more batteries to store your generated electricity. The first battery in my system, and the base of the entire unit, is the Xantrex 1500
. This is a solid, durable package that contains a battery (well, three 17-amp batteries connected together in parallel) and inverter. Here’s part of the product description:

The XPower Powerpack 1500 is a portable power system that produces household electricity for products rated at 1500 watts or less. A clean and quiet alternative to a generator, the XPower Powerpack integrates a 60 Amp/hour AGM battery with a 1500-watt inverter and produces a 3000-watt surge. This system is built to run a range of appliances such as a standard size refrigerator and microwave oven, and office equipment such as a computer, monitor, and fax machine.

The XPower Powerpack 1500 consists of a battery pack that stores electrical energy, state-of-the-art electronics that convert 12 volts from the battery pack to household power, an AC power panel that contains two standard outlets, and a DC power panel that is used to run 12 volt products. These components are packaged into a rugged “cart” with a removable waist handle that allows XPower Powerpack 1500 to be wheeled from room-to-room or outdoors over rough terrain.


Xantrex battery (bottom unit) with cart attachment

For those who don’t know, AC outlets are the standard, three-prong type found in your home. An example of a DC outlet is your car cigarette lighter. So the unit comes with two AC outlets, and one DC outlet. Without needing any solar panels, you could simply plug this battery system into your home AC outlet and leave it connected—the trickle charger will ensure that the battery remains full at all times. If you needed to bug out, you could then grab the battery and go. However, once the battery runs out, and without a way to generate more juice, you’re out of luck. But for your basic weekend excursions where you need to charge camera batteries or power a lantern, it is a great option.


Xantrex AC outlets

Xantrex DC outlet

Note that the batteries in the Xantrex are AGM cells, so they don’t have the out-gassing problems that a wet car-type lead acid battery would have. This means that they can be safely kept inside your living area just fine, whether that’s a tent or a house.

In addition to the Xantrex, I got another battery to be able to store more juice. This one is a 55 Amp/hour AGM battery, which simply sits on top of the Xantrex unit and connects in parallel.


Second battery stored in battery box

An important lesson I’ve learned regarding lead acid batteries: in order to extend their life as long as possible, it is important that they not be depleted more than half their full capacity. If the batteries are used to their full capacity, the lead plates start to get eaten away, thereby reducing the lifespan of the battery itself. In some situations it might be necessary for you to use everything the battery can give, but where possible, it’s best to take care of your battery (by using it as sparingly as possible) so it can continue to take care of you.

Solar panels

Solar panels have dropped in price recently, so now is a good time to buy if you’re in the market for one (or more). I ended up purchasing two 64-watt US64 solar panels. These panels have no glass (unlike most) and are thus quite durable, have a “triple-junction” technology that allows for greater efficiency in generating electricity, and are connected in such a way (unlike many panels, oddly enough) such that if one cell group is shaded or blocked somehow, the rest of the cells are unaffected and continue to perform. Here’s a description:

The “triple-junction” technology used in the US64 uses three layers of semiconductor material so that the junctions are stacked on top of each other. The bottom cell absorbs the red light, the middle cell absorbs the green light and the top cell absorbs the blue light. This spectrum splitting capability is the key to higher efficiency in a smaller panel.

Under higher operating temperatures, solar panel performance changes. This depends on temperature, solar spectrum (light color) and related effects. The US-64 is less affected by temperature than monocrystalline or polycrystalline solar technologies. The result is up to 20% more delivered energy. The size will be slightly larger than a competitive panel of the same wattage but performance is much better in foggy or partially shaded conditions.

Eleven cells are connected in series to produce the required voltage for 12 volt battery charging. The cell assembly is laminated (sealed) in flexible and durable weather resistant polymers that provide long life and high reliability.


Two US64 solar panels attached to batteries

Another option I had previous considered was the Sunforce 60-Watt Solar panel assembly
. However, after reading reviews and upon the recommendation of my acquaintance, I decided that this (fairly popular) system would not be good for a few reasons: the panels are glass-covered and thus breakable; the panels only have a five year warranty (as opposed to the 20-year guarantee many other panels have); the included charge controller and electronics are not very weather-proof; and the panel’s chemistry is amorphous, which is often prone to breaking down after a number of years of continuous use.

So, US64 it was. Each of these (US64) 64-watt panels generates a maximum of 3.9 amps. With the two of them hooked together (128 watts, 7.8 amps), the system needs a charge controller to handle the higher load.

Charge controller

To handle the 7.8 amps (maximum) produced by my two panels, I got a Morningstar SS10 charge controller.


Charge controller attached to Xantrex cart

A charge controller is similar to the voltage regulator in your car. It regulates the voltage and current coming from the solar panels going into the battery. 12 volt solar panels can sometimes put out more than just 12 volts, so if there is no regulation the batteries will be damaged from overcharging.

If I were to add another 64-watt panel, then I would need a larger charge controller to handle the extra load, since my three 3.9 (max) amp panels would be putting out a maximum of 11.7 amps—more than the 10 amp controller would be able to handle.

Meter

Being the OC person that I am, I want to know that this system is working properly and efficiently. To that end, I also decided to purchase a Doc Wattson meter so that I can quickly see how well the system is doing both in terms of juice going from the panels to the battery, as well as how full the battery actually is.


Meter attached to measure generated electricity from panels

Cost

So, the obvious question for those still interested at this point is: “what did this system cost?” For the parts listed above, wires, connectors, and labor for this acquaintance of mine to build it all for me, the total came out to $1425. Here’s the breakdown:

  • $400 – Xantrex 1500
  • $150 – external 55 amp/hour AGM battery w/ cables
  • $710 – Two US64 panels, wired and connected
  • $65 – Morningstar SS10 charge controller
  • $50 – cables/connectors
  • $50 – labor

What’s it good for?

In order to know what you’ll be able to use on a similar system (or any system for that matter), it’s important to make a list of what items you’d be wanting to use (wheat grinder, portable heater, lights, refrigerator, well pump, battery charger, etc…) in a TEOTWAWKI scenario, and then measure how much power each device uses. The best method for obtaining this information is to purchase a Kill A Watt
. Using this compiled information, you would then have a much better idea of how many batteries and panels you would need to accommodate your electricity requirements.

My current setup is to be considered very minimal. Going to the halfway point for my batteries would give me around 50 amp/hours of juice. Running at 12 volts, this yields 600 watt/hours. So, on a single (halfway) battery charge, I could run a 100 watt light bulb for six hours, a 200 watt fan for three hours, or a 1200 watt space heater for half an hour. Here’s a calculator for making similar calculations. You can see how this system is optimal for light, intermittent use—any greater load requirements would necessitate a much larger system capacity. Also note that these calculations are not entirely accurate, because they do not take into account the loss of current through inversion (converting DC to AC). Also, the discharge of a battery is non-linear, so heavier loads will drain the battery’s amps much faster than a lighter and longer load would.

Conclusion

The thing I like about this system is that it’s rugged (solid battery pack cart system, no glass in panels) and portable. I don’t plan to use it very often, but I have it set aside for when I go car camping and if I were to ever need to bug out somewhere. I must admit, the geek in me gets a thrill out of watching the meter indicate that I’m using sunlight to power my gadgetry. Solar power FTW!

35 thoughts on “Electricity During an Emergency: Solar Power Generation”

  1. That’s awesome – thanks for sharing. I have been thinking about power in an emergency situation and had the same reservations as you regarding generators. I like this idea of a portable solar power source – now I just need to figure out how much power I need to get an appropriately sized system.

  2. That’s awesome – thanks for sharing. I have been thinking about power in an emergency situation and had the same reservations as you regarding generators. I like this idea of a portable solar power source – now I just need to figure out how much power I need to get an appropriately sized system.

  3. Very nice, detailed post. The previous owner of my home had a battery power set up that he used to power about 1/2 the house during power outages. He had a durable plastic trunk to house the 5 or so batteries, a charge controller, inverter, etc. He said that he could power the fridge, freezer lights and TV with it.

    He told me an acquaintance of his worked at Novell, and each time the servers were put on battery power due to an outage, the entire battery back up system was replaced. So, he was able to obtain very nice gel cell batteries for something like $20 each.

  4. Very nice, detailed post. The previous owner of my home had a battery power set up that he used to power about 1/2 the house during power outages. He had a durable plastic trunk to house the 5 or so batteries, a charge controller, inverter, etc. He said that he could power the fridge, freezer lights and TV with it.

    He told me an acquaintance of his worked at Novell, and each time the servers were put on battery power due to an outage, the entire battery back up system was replaced. So, he was able to obtain very nice gel cell batteries for something like $20 each.

  5. Sweet setup man. Two questions – can you power appliances at the same time you’re charging the batteries?

    And do you have it set up so that you can plug the unit in at home to keep it fully charged and then use the sun to recharge when you no longer have access to the “commercial grid?”

  6. Sweet setup man. Two questions – can you power appliances at the same time you’re charging the batteries?

    And do you have it set up so that you can plug the unit in at home to keep it fully charged and then use the sun to recharge when you no longer have access to the “commercial grid?”

  7. can you power appliances at the same time you’re charging the batteries?

    Yep. Though obviously if your device is using more juice than is coming in, that won’t be sustainable for very long. But yes, you can do it.

    And do you have it set up so that you can plug the unit in at home to keep it fully charged and then use the sun to recharge when you no longer have access to the “commercial grid?”

    Yes, the Xantrex comes with both AC and DC adapters, so you can leave it plugged in 24/7 in your house on a trickle charge, and then if you needed to bug out, you would have full batteries to use, and would then be able to recharge them using the panels.

  8. can you power appliances at the same time you’re charging the batteries?

    Yep. Though obviously if your device is using more juice than is coming in, that won’t be sustainable for very long. But yes, you can do it.

    And do you have it set up so that you can plug the unit in at home to keep it fully charged and then use the sun to recharge when you no longer have access to the “commercial grid?”

    Yes, the Xantrex comes with both AC and DC adapters, so you can leave it plugged in 24/7 in your house on a trickle charge, and then if you needed to bug out, you would have full batteries to use, and would then be able to recharge them using the panels.

  9. Fantastic post Connor. Having reviewed many portable setups over the years, this is the simplest, most comprehensive, right-on-target post of emergency solar I have seen. Way to go.

    There are smaller, portable solar panels specifically designed for backpacking, etc. but your setup hits right at the sweet spot. Light enough to still be portable but high enough capacity to charge more than just a cel phone. Great job.

  10. Fantastic post Connor. Having reviewed many portable setups over the years, this is the simplest, most comprehensive, right-on-target post of emergency solar I have seen. Way to go.

    There are smaller, portable solar panels specifically designed for backpacking, etc. but your setup hits right at the sweet spot. Light enough to still be portable but high enough capacity to charge more than just a cel phone. Great job.

  11. Connor,

    Were you eligible for any tax credits? I guess you would have to have an installed system for that.

    I see a lot of LED lighting around now for a decent price (for example, at Sam’s Club). I was thinking of using a setup like yours to run LED’s when the power goes out. Maybe on a separate circuit.

    Thanks for the post, you answered a lot of questions for me.

  12. Connor,

    Were you eligible for any tax credits? I guess you would have to have an installed system for that.

    I see a lot of LED lighting around now for a decent price (for example, at Sam’s Club). I was thinking of using a setup like yours to run LED’s when the power goes out. Maybe on a separate circuit.

    Thanks for the post, you answered a lot of questions for me.

  13. Were you eligible for any tax credits?

    Doubtful, since this isn’t a system I integrated into my home to offset energy use from the grid. Perhaps it’s worth looking into, but I haven’t.

  14. Were you eligible for any tax credits?

    Doubtful, since this isn’t a system I integrated into my home to offset energy use from the grid. Perhaps it’s worth looking into, but I haven’t.

  15. During my carreer in the Army, we had 5k generators in a “bucket” atop our M577 command tracks. When we came to a battle position, we would dig a hole large enough to put the gen. in, and added sand bags around the hole. this greatly cut down on noise to the surrounding area.

  16. During my carreer in the Army, we had 5k generators in a “bucket” atop our M577 command tracks. When we came to a battle position, we would dig a hole large enough to put the gen. in, and added sand bags around the hole. this greatly cut down on noise to the surrounding area.

  17. Nice writeup. Do you charge the external battery with the XPower charger? The manual warns against that unless the external battery is also 17 Ah. It recommends “one or more” external batteries, but only says “battery” when discussing charging.

    Where does the load output of the charge controller go? Another DC outlet?

  18. Nice writeup. Do you charge the external battery with the XPower charger? The manual warns against that unless the external battery is also 17 Ah. It recommends “one or more” external batteries, but only says “battery” when discussing charging.

    Where does the load output of the charge controller go? Another DC outlet?

  19. Great article – you talk about the details that most others on the Net leave out. Unfortunately, United Solar has discontinued the solar cells that you used. Could you recommend another manufacturer?

    Also, I’d be interested in your opinion about making the system more robust – either more batteries (so that one or more can charge while one is being used), and/or more powerful (and expensive) batteries which will last longer, and/or solar cells with higher wattage ratings so that batteries could be charged more quickly. I know that in each case the cost will be higher, and that you didn’t intend to replace anywhere near all of the power you get from the grid, but I know many out there would like to be able to run more devices/appliances than your set-up here is capable of. Thanks very much.

  20. Great article – you talk about the details that most others on the Net leave out. Unfortunately, United Solar has discontinued the solar cells that you used. Could you recommend another manufacturer?

    Also, I’d be interested in your opinion about making the system more robust – either more batteries (so that one or more can charge while one is being used), and/or more powerful (and expensive) batteries which will last longer, and/or solar cells with higher wattage ratings so that batteries could be charged more quickly. I know that in each case the cost will be higher, and that you didn’t intend to replace anywhere near all of the power you get from the grid, but I know many out there would like to be able to run more devices/appliances than your set-up here is capable of. Thanks very much.

  21. I found the article from 6/09, re: solar emergency power to be very helpful. My parents live in a very rural area of Virginia and worry as to how they would heat their home in an emergency. They heat solely w/ a wood fireplace/insert but the fan is electric. The emergency unit described in this article seems an excellent option for them. Thanks for writing a no non-sense, practical article! Kudos!

  22. assuming you aren't rich I find PV is practical on a small scale. To power a radio or a light for a few hours each night. On a large scale it is too expensive and unsustainable. I have seen writeups of systems with 20 large batteries costing $4000 for batteries alone. The best outcome is 5 years but often one or more batteries fail in less then 5 years. If this is post SHTF where do you buy 20 new golf cart batteries. The problem is that people think that a post SHTF lifestyle includes refrigerators, TV's, power tools, computers, etc. when in fact if you have lights for a few hours and occassional use of a radio you will be lucky. Don't spend thousands to set up a system that cannot be sustained post SHTF. My suggestion is something similar to what you have shown here and then concentrate on technology you can sustain without electricity and fossil fuels. Of course if you are simply concerned about a hurricane Katrina or something similar then buy the cheapest 5 kw generator you can find and you are ready for under $400.

  23. Very, very helpful.
    I’m new at this, but I think it should be’50 amp-hours of juice’
    and
    ‘yields 600 watt-hours’

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