Anyone have real world experience with these? Anyone now of a similar device in concept that I should look at? They aren't cheap by any definition and they cost more than the conventional generator we installed some years back. (As they become more common, I hope the price goes down.)

As the long term plan (next couple years) is heading to the southwest,* in a locale there that gets a lot of sun (outside Tucson), I'm doing homework on and off about solar. Probably will go with a combination of solar and propane power for backup power, etc., but I'm not dead set on that. (Maybe a woodstove too for backup heat/cooking,† though it wouldn't be as necessary there as it is here and fuel may be an issue.) The biggest problem I've found with solar isn't the panels and installation, but power storage. A device like this seems to answer that.

Anyway, just curious. Thanks. :)

Powerwall2.jpg


* There was a short series of videos on Forgotten Weapons in which Ian went over the off-grid house they have down in the Grand Canyon state. It was powered completely with solar and a small propane generator. As far as I know, however, it is just that gentleman and his common law wife, so their power needs are going to be way less than a family of four and with some small scale agricultural production.

† We've had a number of lengthy outages where we are now in rural Oregon. The combo of a (nearly) whole house generator and a woodstove made getting through them easy. (I say nearly because the heat pump and stove aren't on generator power. Everything else is. We just heat with wood and cook with a microwave or the woodstove.)
 
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I don't think hardly anyone has any real world experience with this product, yet. The price isn't too bad, each one holds 13.5kWh of power. You could probably tweak your usage by switching all your lighting to LED, your TV to LED, your water heater to gas or propane then your largest electrical consumption will be from your fridge, but you can get one that runs off propane as well. As long as you are hooked up to the grid, it will still be cheaper to just get a generator with a transfer switch for your critical load and use it when needed.
 

User 1234

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You need to know the rates and brackets of the local utility in order to do the math on stored power. If you are going to live off the grid then yes they make sense. Another detail to check is whether they need an internet connection for any functions. Many do these days, at least for periodic self tests.
 
If they're that new, might be a good idea to wait and see how they do in the market. Put that way, indeed, it isn't to bad on cost; slightly more than what our entire generator system cost, but not wildly so. We'd almost certainly feed such a device from solar panels. Trying to avoid going totally off-grid if possible as the energy headache on the potential of having to deal with well development. (Some parcels we looked at already have a well in place, while others do not. I've talked to a number of well developers in the area; it is doable, but it isn't easy, simple, or cheap in that state. And our water and energy needs are going to be higher than the average home.)

Anyway, I am going to keep an eye on the development. The two things that kind of kept me away from solar is the fact we don't get a lot of sun a good chunk of the year here in Oregon and the storage needs. If one becomes a non-issue and the other has an easier, "turn-key" solution, then it looks more interesting for backup power or to augment other sources. :)
 
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I can do some math, $14,500 for the two power packs, plus $4,000 for installation, then you are going to need about a 14kW solar system for about another $35-$40K. If you are building a house out in the sticks and they local utility is going to charge you $30K or more to bring power to your project, going off grid looks pretty good, if you are already tied to the grid, shelling out $50-$60K is going to take some dedication.
 
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Anyway, I am going to keep an eye on the development. The two things that kind of kept me away from solar is the fact we don't get a lot of sun a good chunk of the year here in Oregon and the storage needs. If one because a non-issue and the other has an easier, "turn-key" solution, then it looks more interesting for backup power or to augment other sources. :)


A solar array will still produce power on cloudy or overcast days, even when its raining, heck the open circuit voltage at night is almost the same as during the day you just don't get any current. When sizing inverters for a solar array, you have to look at the historical coldest day of the year, since that will be the potential peak output of your array. Remember, solar cells are semiconductors so they are more efficient the colder they are.
 
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No first hand experience, but I had read that their rating is not actually what they store/provide, so I would do some in depth research before putting any $$$ into them. IIRC the idea that Tesla had for those was not standalone power, but as a system connected to the grid to provide grid storage of cheap off-peak power along with their solar roofs.
 
Interesting figures. I vaguely recall some sorts of tax credits, etc. for solar, but it has been a while since I've looked into it. It does make the backup generator and woodstove play (like we did here) seem easier and most cost effective. The only downside, of course, is propane has to be resupplied via truck, whereas solar is always there. (Since we live on wooded acreage, the stove fuel has been easy-peasy as I log my own. That might not be the case in the locales we're looking at though.)

Anywho, I've meandered off the topic enough. Thanks for the info above. I'm going to bookmark some of these sites and check back in the Tesla development.
 
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Have not looked into them, but do know that many of Mr. Musk's minions are extremely intelligent people.
What I have gleaned from your writings, you are very intelligent, well read, and IIRC, a programmer.
For maximum cost savings, appealing to the DIY'er in you, and writing in very general concepts:
  1. Look at your power budget for the past year: peak, quiescent, & average. Anticipate future expansion on those budgets. This is used to size your batteries and output system. Size and quantity of batteries for peak current, desired voltage, and depth of power availability.
  2. Since you have discussed "off grid" living before, I suggest multiple power sources to keep those charged: wind / solar / hydro. Wind and Hydro can use surplus equipment for the power generation. Don't know about Solar.
  3. Once you have your DC bus, you can reprogram the IGBT firing on many brands of frequency drives to deliver power. Three I know of from experience: Siemens, Robicon (now owned by Siemens), and Yaskawa (also used to be sold as Saftronics). These can be purchased as surplus. [Note: If you purchase surplus drives or ones that have not been powered in a long time, recondition the capacitors before powering it up for use.]
  4. Power generation devices charge the batteries, feeding a common DC bus to the freq drives, which convert the power to clean, 3Ø AC. You can run drives in parallel to give you higher, on demand, peak current and provide redundancy if one should fail.
  5. All the above include support electronic systems for charge management and enabling drive phase synchronization.
That's the simple cook's tour, which makes it appear simple, but it's very complex. If you were to go that route, it'd be a fun project, for sure.
 

solv3nt

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As a licensed electrical engineer, I have a dislike of PV and batteries. Even if you're in Hawaii with $0.40 per kwh, it doesn't pay for itself without net metering. In the Pacific NW where power is around $0.10 per kwh, it really doesn't make sense. Lithium ion batteries will last a max of 10 years, PV panels typically 30 years. Inverters and charge controllers usually only last 5 years. After 10 years, your batteries are dead and you have to replace them.
 
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Life cycle of Lithium batteries solely depends on how often you cycle them. Ten years is a good number to throw out there, but it could be as soon as two years or as long as 20.

I’m not in favor of the brand on these batteries. If they are in line with their vehicles, you’ll likely not really own them outright. They probably do some sort of fine print that has proprietary control over them or something.
 

uberguy

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Just an opinion (from a retired electrical engineer), I believe the main point in the OP/context is when low priced on demand hydro power that we normally enjoy is not online for longer than a generator can run for practical applications.

Solar can be a good option, depending on your location and costs (there are ways to save) payback is usually around 10 years if buying smart. And someone mentioned "convert your water heater to gas or propane" while that's nice, in an off grid or many rural situations Natural Gas hookups are unavailable and propane is the most expensive per unit of energy around. If it's just for rare emergencies, that might be the way to go.

But having looked into the subject, a typical electric only home will use about 1/2 the load on the water heater. If you're looking for a step in that direction, but not ready to go whole house solar, in terms of # of panels and # of storage batteries, a solar water heater setup is possibly the best place to start. A fair amt. of details are available by googling.

Solar water heating - Wikipedia

Trojan Deep Cycle (lead acid) are pretty solid for solar applications.

s-l225.webp


Or buy a 6-pack
6 PACK Trojan 30XHS 12V 12 Volt Golf Cart Battery RV marine solar deep cycle GEM | eBay

BTW, I picked up enough Trojan's and panels to do this at my Bend home (outside Bend in the Deschutes, all electric) but haven't had the chance yet, since I plan to install the panels on a workshop I'm going to build first.

Am intrigued by the Tesla Powerwall, noticed when it was first introduced (I recall it came out at $10k?) - but it is sort of the Mercedes Benz of solar storage.
 
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solv3nt

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Another consideration is your roof age, roofs typically last 30 years, if you're halfway in, you'll need to pay to have the pv removed, replace your roof, then pay for a new installation. IMHO, I prefer LP or natural gas generators for emergency backup. The power output is about 75% of that from the diesel counterpart, but the fuel doesn't go bad. The only reason PV or batteries are cost effective, it's because of the green movement, and they're somehow seen as "green".
 
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Duhh ... OK, I will bite. Are these things just some sort of fancy super capacitor thingie? If soossss, what is the capacity in amp hours and at what voltage? Or the discharge wattage?

The capacity and price will get better. We ain't seen nothing yet. In 20 years there will be stuff that will knock our socks off or something like it. Until then I will just look and pass. :)

Nothing wrong with good homemade nickle iron cells.
 
Thanks all for the thoughts, considerations, etc. The Tesla thing caught my eye because it is an all-in-one unit and stores quite a bit of juice.

It seems every so often I get a bug in the bonnet about solar ... then I walk away with the same notion: almost positive we'll set something up for smaller/auxiliary systems and as a minimalist backup if it hits the fan bad enough that conventional fuels are unavailable, but forget primary power for now. The solar water heating might make sense where we are headed though.

I've had mixed luck with gasoline-powered generators, but the propane unit we currently have has been bullet-proof for a backup; easy to maintain, auto-on, and "just works". And the fuel is, relatively, inexpensive, and stores easy. We've got a 500-gallon tank now. I suppose we could consider a 1,000 unit when heading to the desert.
 
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If I were going to do rooftop solar, I'd want the cells mounted as a bank that could be just dismounted from the old roof and set on the ground nearby, then lifted onto the new and remounted as a complete assembly.

When I've doodled out "liveaboard RV" design studies, I've considered having PV's mounted on the shed roof at "base camp" keeping the standby batteries topped off and helping defray costs via net-metering. Just spitballing ideas here. :)
 

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