Main solar system upgrade

rblong2us

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Chatting to an event promoter over the weekend and he reckoned the biggest cost now was the batteries, not the panels.
He was not yet doing his home electricity with solar because he only used about £250 worth a year and he reckoned his battery costs would be a lot greater that this.

No doubt he could get his batterty management a lot better but he did not like the way the panels and event users effected the batteries which seem to prefer steady draw and steady charging.

Think the panels are moving towards the classic 'chinese landfill' status as they cut down on materials and prices continue to fall.

I have learned from your posts Fusor and once again I thank you for taking the time to explain.
 

DCFusor

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Trying to be helpful, that's all.

I currently have 24kwh worth of submarine batteries in my system, that cost me $6k installed (well carried in and wired up, I had to build the shed). They have a 25 year warranty, and are made in Canada by Rolls-Surrette. Right now, there's not really anything better out there, though these are expensive per kwh. I'd almost kill for the tech that's in my Volt, it's less lossy, lasts longer, and only getting better with time. Too bad they won't sell them without a core you return, or I'd be running those.

L16's (6v/385 ah) are fairly cheap, and if you take real good care of them - last about 10 years. A minimal 24 system needs 4, I used 8 on my lower-draw building. Since lead-acids are heavy, they are cheapest usually at the nearest distributor - those babies cost to move around long distances.

Battery life has more to do with cycles, and sub-cycles. For example, if a battery lasts ~700 full cycles (typical for a good deep-cycle type), it'll last 7000 1/10th cycles (about 20 years?). If you just float them and never charge/discharge them (just keep them at float volts with only takes a few milliamps) they last longer than a human lifetime - it's cycling the kills them. Luckily it's proportional. Constantly charging and discharging, except for a little near the top of charge is not good for any battery tech currently existing.

I am personally fortunate that I did all this incrementally. First off - the stuff cost a lot more back in the day, so I really had to learn how to conserve (and Dollar cost averaging worked out well - factor of 6 since I began) - I started with 4 50w panels, one light, and one boom box - that's it. Got used to it, everything else is gravy.

The first major upgrade brought in the smallest top-loader freezer I could find, and total panel power of 600w, but I started needing a backup generator some more. I jiggered the thermostat to run it warmer than normal, just a little below freezing. We used that to freeze 2 liter pop bottles full of water, and used quality Coleman coolers as refrigerators with 2-3 bottles apiece in them - sometimes they'd go 2-3 days without melting all the way. That was one cool trick (pun accidental). The thing is, you could then exchange the bottles in the AM on sunny days, and have the freezer run (it was in a storage shed, sheltered from the sun, unheated, in the woods) only when you had the extra power - this avoided cycling the batteries any extra - straight from panels to freezer in that mode. Worked that for about 10-12 years with 8 L16 (big golf cart) batteries, with a little trick - we put a couple of cheap 12v trolling motor batteries across those and those, believe it or not, took the pounding and kept the L16's from having to deliver a lot of peak current - either direction, which is what kills them.
Even those "tiny" 100 ah troling batteries across an ~800 ah pack made the L16's last 12 years (most people get 4-8). Yes, we had to change them about every two years - but those are cheap, easy to lift, and you get a return credit at WalMart. Even though they are much smaller, they actually have more plate square area than the big guys - lots more thinner plates. That's why they die (thin plates warp and fall apart faster under use), and why they naturally take the peaks better.
An electrical engineer would instantly recognize this as using a "bypass capacitor". That's more or less the function of those things.

Then we did the thing depicted here and it's almost like being on the grid. I have a real fridge (dorm room size), electrically heated hot water (with a new trick I'll describe later), all the amenities - even air conditioning, and sometimes electric supplemental heat when there's extra power - may as well use it once the main batteries are full. And that electric car, which I run down about every two days - it's the main power user now (used to be the fridge, and then this big computer - 4 24" hd displays and all the goodies) that I have on all day most days. But I've upgraded the big 'puter to LED displays, an i5, and SSD's and now that whole rig comes in under 150w - with all 4 hd displays going.

But conservation was and is key. Every single thing around here is on a power strip - the type that DOES NOT have a surge protector - no need for that, and it wastes power even with the thing off.
You'd be astonished how much that cuts your use when all those 5-20 watt "vampire loads" are gone from running 24/7 when you don't need them. Things like soft-on TV's, microwave ovens, cable boxes, and the filters in home entertainment systems all draw a bit, and it adds up to a couple hundred watts even here where I took care to buy the right ones. But...they spend almost all their time fully powered down, and I only hit the power strip on when I need whatever that thing is.
That's a lot of kwh a day - .2x24 is half a kwh that I don't cycle through my batteries, even though I do indeed have the panel power to make up for that - I'm conserving battery life here and rarely use more than about 10% of a charge to make them live longer - and they are showing signs of living "forever" - no noticeable degradation in about 6 years so far. If anything, they act a little better than new with the new charge controllers, they seem to like that.

So the upshot is, there's a lot of up-front cost to doing it the way I do, but then, nothing for long periods. I've got panels 30 years old that are still 70% of new output. The other cost was learning to conserve, "walk lightly on the earth" which isn't really a cost after you get used to it, it kind of feels good, like you're doing the right thing.

I have never had an unplanned power failure, ever. We shut things down for about 2 min once to do some battery work. That's it - since 1979. This is the best UPS system ever!
 

ancona

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DC,
Let me see if I read that right. If I want a battery system to last essentially forever, all I have to do is to size it out so that when running all my stuff all the time i only draw then 10 or 12% because I have so many batteries, they will last a hell of a lot longer?
 

dontdeBasemebro

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My phone and bike batteries get topped off nightly, and I try to choose chemistries that can go more cycles when possible.


DC - have you looked around for a totaled Volt to pull the battery from? Maybe the insurance vultures reclaim that part already if it survived.
 

Aubuy

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OK, every time I see the title to this thread I keep thinking you mean something like let's re-name Uranus because people always make fun of it....and then I re-read it and realize you are going in a different direction. :paperbag:
 
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DCFusor

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Not sure what happened last night, but I lost a post here.
ancona - yes, you read right. You should size batteries so you cycle them around 10%/day.
Less than that, and with current tech, the self-discharge starts to become an issue with wasted power, and more %/day is going to shorten the life. The curve isn't quite 1/% cycle amount straight line, but up till about there, it's pretty close.

No, you can't get a totaled Volt. GM has it as a "bet the company" car, and they get them all. Not many have been wrecked at this point.
 

ancona

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DC,
A lot of the facilities I demolish at the Space Center have enormous UPS units. I am talking about 750, 1000, and 2000 Kv UPS units. Two years ago we tore down the Merritt Island Tracking Station, which was equipped with one such unit. No one wanted the hardware because it was way outsized for even a small business, but there were 225 giant AGM 24 volt batteries. I sold them all for 100 dollars each, but now I am thinking I could have done something else with them, like run a cowboy system on my home with my 19 panels. Had I kept fifty of those batteries, I could probably have done exactly what you're talking about. In fact, the next system I come across I may just keep and use at the house. I have a job I am under contract to perform architectural demolition for, which involves an UPS unit about the size of two refrigerators and a stack of about forty batteries. the electrician apparently wants the system [it's being replaced for Orion] but might consider selling it to me for a few grand.

Would I be insane to put one of these monsters at my house?
 
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DCFusor

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My experience with AGM's is not ideal. They are a lot touchier about charge/discharge than regular old flooded lead-acids - you have to treat either with kid gloves, but AGMs more so - you can't for example "equalize" those without wrecking them pretty quickly. In a big system, equalizing is a fairly important thing to be able to do. That's a controlled overcharge that accomplishes bringing the few undercharged cells in it up to full charge, while overcharging the better cells - causing some "boiling" or actually electrolytic O2/H2 generation with loss of electrolyte in the better cells.
In a normal battery - you can just add a bit of distilled water to the cells that lose it. In an AGM, well, it's "maintenance proof". AGMs are great for a rarely used system, where they spend almost all their time floating at full charge, with rare uses - most UPS systems make that (correct) assumption in the design. They are OK in cycle use, but only OK, and tend to not live as long. A UPS system is designed to "beat hard" on batteries - more of the capacity/hour is used during an outage, than a "real" solar system. That said, they'll work - they just won't live as long in that service. They are in general the design of lots of thin plates, vs a few thick ones for the same capacity, which do wear out quicker as the plates warp or are degraded and the paste falls out of them. "Real" solar batteries have fewer but more robust plates, but are designed for C/15 or so discharge rates, max (eg a 15 hour discharge cycle).

I'd carefully evaluate how good the inverter is in the UPS - there's a good chance it's not as good as the stuff I use here - in efficiency and noise, since computers (believe it or not) are in general less sensitive to waveform than many other things. You might just want to grab the batteries and build your own system otherwise. You'd still need a solar charge controller (they all have special settings for AGM above a certain quality/price level), and you'd probably rewire the battery system to some voltage your inverter and solar controllers can agree on.

My system runs 24v nominal DC. The current sweet spot is around 48v (these tend to go in increments of 6v nominal). That's where you get the most power/dollar out of the electronics going in and out. Most of these electronics are in some way ampere limited by current semiconductor tech. So at a higher voltage, you can get more watts out of the same parts - watts = volts times amps.

I'm running my panels in series strings here, so that I'm pumping about 90v or more down to the controllers, which has a switching supply to "impedance match" that to my 24v batteries, and then running a number of 24v input AC inverters off the battery pack (redundancy is good, and in my case, more efficient, since some of the inverters sit in search mode till say, an air compressor or lathe is turned on). Works great - but for the same bucks, the controllers would handle more watts per at a higher battery voltage (they are amp limited on the output), and so would the inverters - pretty much the same model other than input volts will put out say 7kw for a 48v input, vs 4kw or so for 24v - same cost, but different internals, so your inverter kind of determines what the pack volts have to be (or vice versa). AFAIK, there are not any good inverters that have changeable input voltage - you lock yourself in when you decide that and buy the model that is set for the volts of choice.

FWIW, I'm using all Xantrex stuff here, it's been very efficient and reliable. Not perfect - their proprietary version of the CAN buss they use to talk to one another and give you that nice display of system status has limits on how many things can be on it at once, and I've hit that limit here - and passed it. I have one solar controller in my system that is "on its own" which makes the aggregation of charging numbers and sync between the controllers a bit off, but I've learned to "interpret around the known system reporting errors" there - and the reason I needed so many things is that I'm using that lower end battery pack voltage...
 

ancona

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DC,
Thanks for all this valuable info. When I go the battery sites, all they do is talk about how the product they peddle is the best thing since sliced bread.

That said, I have encountered every conceivable type of battery. I've seen nickle iron, AGM, lithium, NiCad......you name it. At a building I cannot name on the Cape side, they have built their own batteries. They're huge aquarium looking things with lead plates and acid. The room itself is absolutely full of them. They do X air changes an hour and have a dedicated Leibert unit to keep the room at a habitable temperature, because apparently these things produce a lot of heat. The long and short of it is that these purpose-built batteries can and do provide a huge amount of electricity. When I come across another one of these monster UPS units, i will certainly avail myself of your expertise, since you do in fact have enormous experience, having experimented with so many variations and combinations of power storage.
 
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rblong2us

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lead plates and acid ?

not exactly groundbreaking technology )-:

just large scale I reckon.
 

ancona

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They're enormous rblong, fucking huge. I would guess they are forty or more inches long, 26 - 28 inches wide and two and a half feet high.
 

DCFusor

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There's a lot more to lead-acid than lead plates and acid, of course. The alloy of the plates matters. Cars use one, that is terrible for cycling but good for avoiding water losses - hence "maintenance free" or what I call maintenance-proof. They have utterly different characteristics than deep cycle batteries from that alone. The plates are a grid that has lead oxide or sulfate pressed into the squares, and are separated by different things also depending on design. Then there's the optimum acid concentration at full charge - varies all over the map. LA batteries, in other words, are quite complex and span a big range of capabilities.

As to ground breaking tech, that might be good in diggers, but quite a bit of experience with ni-cads, nimh, li ion (4-5 different technologies alone) - shows that it's smart to wait till something has survived the test of time. With the latter techs, there have been real serious issues with the electrodes, which instead of converting from one lead compound to another, actually have to ab and desorb metal ions, are toxic, flammable, and in some cases, not reliable. Not only that, many of them have far more "throughput losses" or larger range of voltages - for example, even the flooded ni-cads they use in locomotives have such a huge range - 50% - of volts in their normal charge range that almost nothing in the solar biz works well with them - you can't use that wide a range within a single cycle.

The above stuff is all called groundbreaking tech, or was when it was introduced. None has lasted more than a few years so far. You make that size investment in your 'stead - you want something you KNOW will last. Li-ion might take over in the end, certainly where weight matters. Vanadium redox will probably eventually take over solar - capacity only limited by "fuel tank size" and no degradation over time, but the cell separators made of nafion are super expensive.

In the Volt, to make Li-Ion work...
3 strings of 96 cells in series, then those 3 in parallel.
One thermostatically controlled cooling/heating fin per 3 cells. One relay and resistor per cell to hold back the good ones when topping off (equalizing) the pack, since overcharging Li kills it dead on one try. Over 100 microprocessors to control all this, pumps, radiators, heaters - all stuff that eats power itself, and is a reliability concern. That's the state of "ground breaking" right now.

What would you essentially bet your life on?

Ground breaking is for diggers...:rimshot:
 

mike

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DC,
That said, I have encountered every conceivable type of battery. I've seen nickle iron, AGM, lithium, NiCad......you name it. At a building I cannot name on the Cape side, they have built their own batteries. They're huge aquarium looking things with lead plates and acid.
OMG you gotta post pics of that stuff!
 

rblong2us

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Ground breaking is for diggers...:rimshot:
gets my vote anyday

and its gotta burn diesel !

although I do sometimes ponder a kuntstler 'world made by hand' with no diggers or petrol chainsaws ............

Just how we would get the raw materials for our basic needs remains scarily elusive :flushed:
 

bushi

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...yeah, chainsaw w/o petrol (electric) is a bummer.... It will either need to be carried by a horse, or otherwise, will let you half-cut one tree, on one charge :rotflmbo: For anything resembling actual "forest husbandry", I was thinking about an actual "battery pack" -i.e., a backpack, full of batteries (to the extent practical... weight), and then, a short cable to the chainsaw - which in turn, would only have motor in it, and would be lighter than even a petrol one. Although, having that thing connected via cable to a heavy battery pack on your back... kinda doesn't like the idea, either. Although my stepfather is using electric chainsaw (grid powered) around the house (because it is so much cheaper to run, than a petrol one), but you are not tied to the tool with a cable, this way.
 

ancona

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Bushi,
We have [at my firm] a pretty respectable fleet of battery powered tools for interior demolition. One item is a Hilti 24v reciprocating saw. I have used it to cut logs as large as 12" in diameter and it works quite well. Hilti is one of the best power tool manufacturers I have found. their stuff is built to take abuse and for near continuous duty. If properly cared for, the batteries will last for years. I have three batteries for each hand tool, which allows me to rotate them through charge cycles during the day and keep on working. Of course after the balloon goes up, all bets are indeed off, so whatever batteries I have will likely be the last ones I'll have.

What I really want is a three foot long buck saw with a couple of replacement blades and an even longer twin handle saw for felling trees. We have thousands of Australian pines around here which grow straight and incredibly tall [for Florida anyhow]. i know of a stand close by with probably a thousand of them, with an average height of a hundred feet or more.

My primary concern is fuel for cooking and heating well down the road from SHTF.
 

DCFusor

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I use an electric chainsaw, whenever I can, FWIW. It really sips the energy, which I can provide from various sources. One is a tiny portable generator (inverter type) that auto-throttles down when there's a low or no load and will run like that all day on a quart of gasoline.

When I can drag the tree - or major chunks of it, up close to the infrastructure, I run it on the solar system. It's a lot lighter than a gas saw, and has more torque than even the big boys. You have to be careful not to stretch the chain right off it.

This would all be practical with zero fuel should someone make an electric version of my small (but heavy and torquey) tractor to just cut a tree into 3-4 pieces and then drag them back to cut them up finer.
 
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