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Portable Solar Power and Energy Storage – Off-Road or Off-Grid for just $700

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Portable and affordable backup solar power.
Portable and affordable backup solar power.

There has been a lot of talk about solar power, renewable energy, and energy storage over the last few years, and many might come to the wrong conclusion that such systems are neither portable nor affordable. An associate of mine was testing out his off-road, off-grid solar power setup, and he came to some interesting conclusions.

Like me, he likes the outdoors and, while we might be willing to deal with a few off-grid nights for a bit of peace and quiet, our wives and kids tend to destroy the calm with their whining for the comforts of home. To tell you the truth, I believe that every single camping trip I’ve ever been on has been in the rain, so I can understand why bringing along some of the comforts of home can be attractive. Unfortunately, those “comforts” might include things like the laptop, a television, or a refrigerator.

Going beyond this, what happens when the comforts of home are taken away by power outage, whether by storm or blackout? This tends to happen regularly where I live in the highlands of Perú, such as last night when we lost power for a few hours. Candles only go so far, and do nothing for the refrigerator, laptops for work, cell phones for communication (the local cell tower has backup power) or the electric shower. A cheap Chinese 800W generator is a little over $150, not to mention fuel costs. On the other hand, what about the solar power, via the abundant sunshine we have here?

Depending on how much power you need, perhaps a small solar power system and energy storage is all that is required? Just for the basics, and as long as you have a few hours of sun, you could run a television, charge cell phones,  and laptops, even keep a 12 V cooler running for days, all for a $700 system, as opposed to a $30,000 7.8 kW solar power system.

The solar power unit, at least in this setup, tested by TacomaHQ, is a 100 W Renogy solar panel and charge controller, which was tested putting out 22.1 V at 7.5 A in full sun. The energy storage consists of an ArkPak with a 93 Ah deep cycle SLA battery. Judging from the calculations, it takes about six hours in full sun to charge the ArkPak by 50 Ah. Unless you run down the ArkPak every night, this could be the perfect off-road or off-grid solar power and energy storage setup. Add a second solar panel, another $170 or so, and you could get a full charge every day, in case you want to watch movies on a 40” flat-screen television.

Image © TacomaHQ

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4 COMMENTS

  1. IronEdison well, part of the issue is not worrying about hooking up your entire home to this system. it’s still plenty of energy for minifridge, mobile phones, even laptops. on the other hand, you’d be out of luck trying to hook up an air conditioner, full home theatre system, hair dryer, or electric shower. full-home solar power systems are another matter altogether.

  2. @Jason Lancaster IronEdison Great points made by all. The main thing I’m thinking about, however, is that it enables reliable off-grid renewable energy. Investing in the proper technology: good solar panels, charge controllers, a good deep cycle battery pack – makes a big difference in making the whole system work.

  3. IronEdison First, it’s important to distinguish between deep-cycle batteries and standard starter batteries. While the battery chart you posted (which seems to have come from http://www.solarelectricsupply.com/solar-batteries/deka-solar-batteries) is for a deep-cycle battery, people reading might not realize that your recommendation of 30% is more in line with the discharge amount for a starting battery rather than a deep-cycle battery (which are frequently advertised as being rated for discharge at or near 50%).

    Second, since I wrote the review about the ArkPak and have interviewed the folks making it, I can tell you that the charger/reconditioner in the unit is world-class. While a battery’s ability to recover from multiple deep discharges is largely determined by design and quality, a good smart charger makes a huge difference. The ArkPak’s charger has 7 modes, can push out as much as 6amps, and is carefully calibrated to help maximize the life of deep-cycle batteries.

    Finally, just as your graph shows, daily discharges of 50% would still result in years of service.

  4. 93 Ah at 12 Volts = 1,116 Watts of total energy storage in this system.  
    Check out the Vmp and Imp of your panel.  That 100 Watt panel would put out 6 Amps at 17V.  When you convert this to 120 Volts AC power, this is 0.83 Amps of standard electrical power coming from that solar panel.  
    With a lead acid battery, it’s recommenced to use only 30% of the total battery capacity (50% max discharge).  Please see attached chart that compares Depth of Discharge with Cycle Life.  The 93Ah battery would then provide 334 Watts of available energy at 30% depth of discharge.  That’s not much.

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