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Discussion in 'Energy, Environment, and Policy' started by nwdiver, Sep 23, 2016.
I thought a poll might help further the discussion... please choose all that apply...
My most likely next solar project will be the new house we're buying. We'll be well out in the country, where I'm told the local power grid is excellent. Nonetheless, the house makes use of pellet stoves as an important heat source, and pellet stoves need about 600 watts of electricity get started, and then a lower ongoing level to run a fan to move air.
So if/when the power is out, no heat. First low end thought is a portable battery / UPS like this:
I might need 2 or 3 of them though - looks like getting a stove started will eat half the stored power (10 minutes at 600 watts), but after that, the fire will keep itself going, so its just running the fan.
But what I'm really thinking is some kind of battery backup with solar on the roof, and the ability to disconnect from the grid when the grid is down. My ideal case would be turning off all the 220 circuits, but having all of the 110's still up and available. 7 kwh sounds like not enough for a multi-day outage and only 110's, but 20 or 30 kwh plus some aggressive management of what we turn on and keep off sounds very livable. (And the pellet stoves can run as much as we want them to!). Heck - we can even charge the cars off 110 during an extended outage with careful planning.
On balance, I think I'm a little bit above the battery backup > 4kw and >10 kwh, but not massively so.
My impression of the expense of this kind of a setup is that it'll be too high to worry about for the next year or so, but maybe over the next 3 years prices will be down, and ease of installation will be up.
Of course, the house also needs a solar system. I don't yet know how they will interact with the local PUD.
All of this, in my mind, being the next step down the road to energy independence, after the first step of putting up grid tied panels.
We are right now sizing and specifying for a whole house system to put in our house in Rio de Janeiro. We intend to go off-grid completely. We did it a couple of decades ago for an island in the Bahamas and discovered a few days ago that the system is still functioning more than 20 years after we installed it. The big problem here is the very high import duties as well as a complete electrical renovation we will do as well. It's a big place so the project will be sizable. I just finished sizing it and estimate we'll have payback within about 12 years, not to mention feeding our Model 3 when it finally gets here.
I am guessing our Miami Model 3 will arrive a couple of years before the Brazilian one.
Depending on your portability needs I've found that buying each component separately is usually more cost effective than buying one component.
If your goal is a bit above ~4kW ~10kWh and the use will be primarily for backup I'd go with a 48v bank of golf cart batteries... 24v if your budget won't allow $1k worth of batteries.... but the bump to 48v would be more than worth it. Economies of scale work... I'm pretty sure that the good 'ol GC2 is the most commonly produced PbSO4 battery in the world so you get the most bang for your buck. You can usually find them at Costco or Sams for <$100.
If you have an existing grid-tie system I'd recommend an AC couple capable off-grid inverter. The two that I'm familiar with are the Magnum Energy PAE series and Radian Outback. That saves you the cost of a charge controller but it's not as user friendly since the grid-tie can't control its output. More about AC coupling here:
If you want a stand alone system you'll need a charge controller and your inverter options open up a lot. IMO for larger systems with >1kW of panels Midenite solar offers the most cost effective charge controllers.
The tip about acquiring components separately is a good one - something for me to keep in mind.
For what I'm thinking about, portability isn't particularly a feature I'm looking for. The particular item I listed was more intended to express a manifestation of the initial idea - that the bare minimum coverage we need for a winter time power outage is enough stored energy to power a 110v AC appliance (pellet stove) that has an unfortunate power curve.
Namely, on startup, it runs a heating element to get the pellets lit (about 10 minutes at 600 watts from reading a couple of pellet stove manuals - I don't claim that to be perfectly accurate). Afterwards, new pellets light from already burning pellets, so the heating element turns off. However, there continues to be a low power fan moving air through the stove. The issue here is no heat if the power is out, but with very little available power, an unlimited (well, limited to the bags of pellets available ) amount of heat can be had.
That particular unit is 1000w peak and 500w continuous. I suspect that will prove adequate for the immediate / short term need. It's also ~288 wh of storage - that's good for several hours for running a 50 watt fan, but not good for a day.
A bit more digging around on Amazon and I found this gadget:
2.6 kwh of energy storage, with the ability to run high wattage 110 appliances (pellet stove will be trivial). Add in the solar panel recharge option, and as long as we define off-grid as "pellet stove runs", then it looks like this could do the job.
Of course, up in this price range, it starts making sense to think about a powerwall, a cutoff switch for the house when the grid is down, and liberal throwing of breakers to disable most power consumption while the rest of the grid is down.
For today, I'm mostly listing it as a means of expanding people's idea of what's available out there.
For my own part, I'm not ready to act today, and beyond a cheap / temporary solution, probably not ready to do anything this fall. One thing I like though is that lithium is starting to work it's way into this storage market as well. I don't claim anything resembling expertise, but from what I've read about lead acid battery systems, I lean towards finding a lithium option instead. I know it's going to be a lot more expensive - how much more expensive is something I'm keenly interested in figuring out.
If this thread has legs I'll try to be more participatory in a few weeks...back in the land of Bandwidth and Connectivity....but from many years' experience in this I'll say specifically that the utter key to a good system is an adequate battery bank. More later -
I'm certainly trying to help get it legs. My hope is the more general off-grid and "semi-grid" (I made that up) discussions can come here, especially as it relates to building and implementing for various outcomes. That'll keep wk057's thread less cluttered.
Of course at some point, we'll have overlap here and with Tesla's storage and production system.
Two important takeaways I got from following along @wk057's thread over the months. I don't have anywhere close to the technical know-how to do a DIY system like he did. I don't even have the technical knowledge and expertise to do the non-electrical components of his system (like boxes and racks).
AND - the difference between going off-grid in short bursts (possibly even measured in days) under reduced living conditions that are better than having no electricity at all, and going completely off-grid is HUGE. The corner cases are rare, but common enough that the over-engineering to account for them consumes a lot of money for small incremental utility.
So I'm personally unlikely to ever get fully off-grid (by which I mean we need to see a 1 - 2 order of magnitude drop in the cost to contemplate fully autonomous grid living. But the technology at an expense level I can stomach for a generator replacement to live through the grid being down - that sounds very achievable in the near term.
To me it seems like we won't be using lithium batteries as residential storage 10 years from now. The reason we use these expensive batteries is that they check all the boxes for laptops, EVs and other portable devices. Weight is an absolutely huge concern. Who cares what the weight and footprint are when the thing is sitting in the corner of your basement?
Powerwalls are fine for people with money today, but for the everyday consumer there's got to be a bunch of cheaper alternatives that are actually better options for residential use(can't catch fire, etc).
I've been intrigued by this aqueous hybrid product since I heard about it and could see tech like this taking over the residential market, especially when talking about going off grid which requires a LOT of excess capacity. No reason this shouldn't be a cheap option once scaled to an Elon-level.
Project Spotlight: Home Battery for Off Grid Living in California
I've also been intrigued by the Aquion Energy system, and I'd say it's certainly in the solution space I'd consider. I agree in principle with the idea that for stationary storage, you can give up a lot of size and weight relative to mobile applications.
However, I also expect a pretty heft discount relative to the alternative. Not 10% - probably closer to 30 or 50% - though I haven't really thought about it much. The real point being that for stationary storage, I expect to trade off size and weight as relatively unimportant vectors, to get the price of the system down dramatically.
It's been a while since I've talked to anybody, but the prices I saw back then were high enough to leave me thinking Powerwall might be the cheaper alternative. It may be time to look again soon.
My concern with this technology is that in a sense, they're going up against the dramatically larger volume in the lithium battery business, with the corresponding economies of scale. It may be that on paper, dirt and salt water should make for a lot cheaper battery. In practice, if these folks are building MWh, and the other folks are building GWh, that's 3 orders of magnitude difference in volume. That alters supply chain behavior and on and on.
If anybody does get more info about the Aquion system, especially including a sense of the price per kwh for an installed system, I'd be very interested in learning those details.
(I'm already picturing where the M / pallet sized battery might sit and provide 20-something kwh of storage; that sounds like comfortable off-grid living in stretches with enough solar, and I hear there's a new solar roof thing coming ...)
I've always wanted to create a portable system in my garage just for testing out and emergencies.
Portable Panel - https://www.amazon.co.uk/dp/B003SJ2B8O
Small battery - https://www.amazon.co.uk/dp/B00JJDPTYQ
I have a 10kwh system on my house right now. I looked into battery back-ups a few years ago and the only real option was a car sized lot of large batteries. Also in the $12,000 range so I gave it up and figured to wait on something better. Well now Tesla has something better. It is still too expensive for my needs but will probably get the Powerwall in the next year or 2 and keeping an eye on advancments. I would love to be off grid!
$6/w?!?! I would steer clear of Goal Zero... they're absurdly overpriced
I've heard good things about Lensun panels... they're half the cost and semi-flexible.
If you're comfortable ordering from China I've ordered 300w... they should be arriving soon so I can write up a review in a few days.
Not sure what's available in the UK but I wouldn't pay >$1/w for a tempered glass PV module and inverters shouldn't cost >$0.50/w.
Do you mean 10kW?
I've got a 10.7kW system tied to a 8kW grid-tie inverter. A couple years ago I bought a Magnum Energy 4448PAE for $2200 and 8 6v Golf Cart Batteries for ~$1k. So for <$4k I can have almost full power off the array and ~4kW at night with ~10kWh of storage. If you want something more user friendly than AC coupling you can get a high voltage charge controller for ~$1500; This would bypass the grid-tie and charge the batteries directly with would in turn power the off-grid inverter.
99% of the time being 'off-grid' isn't worth it but having some backup power can we worth its weight in gold if there's an extended grid outage.
With sustainability in mind, I prefer a on-grid solar solution, where the grid is my battery (i.e. net metering). That is after all less taxing on the environment than manufacturing enormous batteries.
The hurdle to net metering is primarily political, since the electricity suppliers are lobbying against this resource efficient use of solar.
So for most places Elon Musk's batteries are a resource heavy, technical solution to a political problem.
A possible side-effect of more and more people installing solar + batteries could be that net metering becomes acceptable. It could also go in the direction of Spain, where private solar installation is taxed to death, to protect the electricity companies.
Think about that when your next election comes up.
> pellet stoves need about 600 watts of electricity get started, and then a lower ongoing level to run a fan to move air. [adiggs]
You could light stove using a propane torch, drilling a hole if necessary to get it poked into the firebox. The original attraction of burning pellets was that the fuel supply could be handled by even a seriously handicapped person who would be unable to open up stove and reach inside to start the fire. The fan is probably necessary to avoid overheating or at least maintain efficiency. But you could replace the 120v AC fan with a couple 12v/5v DC computer whisper fans etc to match almost any power source.
You're probably right about the changes to the fans that you describe. The fundamental problem is I'm a data/software guy, and am pretty much clueless when it comes to doing actual electrical or pretty much any other construction type work. At least today! Someday, I can readily imagine doing the practice and study, so that even a simple sounding bit of electrical work, actually sounds like something I could do.
For the time being, I get what comes in the package
I talked to Aquion briefly at the solar show in San Francisco in July. The pallet size 25kWh 48VDC package was ballparked for me at $25,000. That's $1,000/kWh. Um, no thanks. I'll wait for a good inverter with a battery interface that will take an intact salvage EV pack. Salvage Leaf packs should be around $100/kWh.
Good info @miimura. I figure that needs to be about $6k and then we're talking (which is just an initial guess on my part at what I think Tesla's batteries will cost, and the size of the /kwh discount this battery needs to carry to make it competitive. If they're priced the same, then I'm not seeing a compelling reason not to get the lighter weight and smaller package.
If anyone wants seriously robust cells for use in solar or wind power applications and has space for a fairly large array of cells, these are absolutely teh best:
These massive things were originally developed for use in remote telecommunications relay sites by legacy AT&T. Their original rating was 2000AH and the cells weigh 350 pounds each.
I bought 36 of these used, when building a remote power system for an island in the Bahamas. They were on average 15 years old when I bought them. They are still in use with no maintenance other than 'whacking' each cell periodically with a wooden object to distribute the electrolyte evenly, equalizing them ever six moths or so, and adding distilled water whenever the electrolyte level becomes low. Every few years you need to remove the connections clean them properly and reconnect them. I doubt there is any real life limit to these monsters.
I am planning to buy them again for my Brazil house, and expect them to outlast my life.
For sure. I didn't buy an HDTV til I could get one for $1200, so i wouldn't buy an Aqueon until it was maybe $250-300/kWh. Considering why and how they manufacture today, I think think a quarter of the current price would be easily achievable at scale.
Imagine a completely safe, nontoxic battery pack made out of simple materials for ~$6k that could take you off grid if you so desired. Pretty insane to think about what the world will be like in 20 years when even that price point will be considered quite excessive.
Free energy is essentially here, why are we not partying???
One challenge the Acquion folks have is that the upper bound on what I would pay for their product, based on what I know today, is what Tesla is charging for the PowerWall. The real upper bound is a reasonably large discount from what Tesla is charging. The way I understand things right now, I rate them equally usable as basement / inside the house installs, with the PowerWall winning out for size and weight reasons.
If they're losing for size and weight, and they're a wash (at least in my mind), on their safety and emissions for in-house installation, and they're kind of the same ballpark for cycles and power delivery, then I think that leaves price for them to compete with.
I really want options.