How To Get The Benefits Of Powerwall On A Shoestring Budget

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Last Updated on: 30th November 2024, 10:27 am
Ideally, we’d all have a rooftop full of solar power and a big bank of batteries in a large garage. This would not only power our homes 24/7 with clean solar power, but it would also keep the power bill down, feed clean energy to the grid, and keep your home powered during emergencies. But, not everyone has the option to buy all this.
For one, even if you have the dough, we all don’t own a roof and someplace to put the batteries. People living in apartments, people who rent a house, and people in many other living situations aren’t allowed to install this kind of a system or it wouldn’t fit where they live. That alone probably excludes around half of people.
Even if you own your own home and it’s in a place that’s suitable for solar, that doesn’t mean it’s free. As expensive and difficult as it is just to buy a house these days, many people can barely afford to even buy the house. This leaves you not only with bills you can barely afford in many cases, but not enough room in your debt-to-income ratio to get approved for the loan. This is particularly stupid, because you’d still be expected to pay the utility bill, right? So, the best you can do is get on some sort of clean energy plan with the local utility if you care about the environment, but that doesn’t lower your bill or give you power during an emergency.
However, there are some other options that can give you some of the advantages of an expensive full-home solar setup, and this video explores one that’s dirt cheap:
In this video, he takes a small power station and puts it to work in a very non-traditional role: demand shifting. Because his electric company has high rates during certain hours, he wanted to see if it’s possible to run the fridge on battery power during that time, and have it charged up on cheaper power from lower rate times.
To do this, he took a power station with pass-through or UPS capability and paired it with a lamp timer. The pass-through capability is important because not all power stations can power things while also charging. In this case, the battery needs to both let power go through for the fridge while also charging up during off-peak hours so that it will be full. The plug timer (or “smart plug”) simply interrupts the circuit charging the power station during certain hours so that it will power the fridge from battery power during that time.
Ultimately, the experiment worked well. Modern fridges only use 100–200 watts of power during compressor cycles, and almost no power when the compressor isn’t running. So, even smaller 300 watt-hour stations can provide enough power to keep a newer refrigerator running for hours. The lamp timer does a great job of cutting the power off at the right times and keeping it from drawing power during the wrong times.
All this having been said, it probably doesn’t save a lot of money. Even when rates are 20 cents per kilowatt-hour higher, moving the fridge to battery power might only save one third of a kilowatt-hour, limiting your savings to only a dime at most. In the most insane power markets, it might save you a quarter a day, or $7.50 per month. This would mean that a $200 power station pays for itself in about 26 months, which is within the expected life of such a unit.
What this would be even better for is dealing with power outages. If you live in a place that frequently gets power outages, keeping the fridge cold for a few more hours can help keep food from spoiling. If preparing for a long power outage, pairing a larger power station with 200 watts of solar panel and charging it up during the day can help keep food safe for a lot longer.
So, in the end, the power savings barely pay for the unit while you end up reaping the additional benefits of dealing with power outages. Or, if you can shift the peak demand or all of the power needed 24 hours per day to a small solar panel, you can end up saving a lot more.
Going Bigger Is Better
If you want to save money and prepare for larger power emergencies, larger power stations can give you more of both benefits. While a fridge draws a lot less power than most people think, more power hungry things like heaters and air conditioners can draw over 1,000 watts when they are running. All in all, they’re only on a 50% duty cycle, meaning that for every hour, they pull maybe 500–750 watt-hours. But, to run such a device for peak load times, you’d still need to do that for 3–4 hours, so you could need as much as 3 kilowatt-hours of storage just for one window AC or space heater.
Shifting that 3 kWh can save a dollar a day in the worst markets, or $30/month. Given how expensive such a power station is ($1500), that makes the payback take around four years, which makes it viable. If you can add solar panels (temporary install on a balcony or roof using zip ties, rope, or sand bags) and shift the peak demand to solar, you can save even more and pay it off faster with savings.
Flexible Emergency Power
If I lived in an apartment with a balcony, I’d probably take a 1.5 kWh or larger power station and charge it with as much solar as I could zip-tie to the railing. I’d run the cabling from the solar into the apartment, where the power station sits inside in comfortable temperatures. Then, I’d either run an extension cord out to the right appliance or wheel it in there during peak hours.
Nicer power stations often have app connectivity where you can set times that the unit charges from the wall to top off, turns the outlet on and off, or otherwise allows you to configure it for maximum savings and emergency preparedness. All in all, this would still be somewhat expensive ($1000–3000), but it would pay for itself in power savings (or cover its own payment if financed) and allow you to have that extra flexibility, use on camping trips, or more.
Featured image by Jennifer Sensiba.
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