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Hippies, Re-doubters, Van Conversion Guy, you're all on short notice in this thread. Consider this your first warning. Everyone welcome in, even the aforementioned! If you have questions about what off-grid solar systems are comprised of, what they typically cost, what it takes to operate them, blah, blah, blah; fire away! I know system sizing/design, battery care fundamentals, major brands, system operation, and tons of weird rear end poo poo I never expected to learn. For instance, I can also answer a poo poo-ton of water pumping questions, and know a hell of a lot about moving water from A to B. I've been doing it for a while. Basic off-grid systems involve an array of solar panels charging a battery bank. The battery bank stores energy like a gas tank in a car. You pull energy off the battery bank to run the household electrical loads. That's about it. It is terribly loving complex. Thread is not for your grid-tie dick-waving system, keep that poo poo on the roof. Grid-tie is fine and good, but we are specifically talking battery-based here. I'm putting on a Resident Evil: The Final Chapter dvd I got from Netflix, and making some dinner, will be checking in regularly tonight and all weekend. Fire away questions.
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Mar 3, 2018 03:44
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So I assume you live off the grid? Give us an idea of the scale of things. How big is your house? What’s the capacity of panels and batteries (including the area they take up) that it takes to run it? Do you run an off the grid house just like an on the grid one in terms of consumption? No worries about the fridge, lights, appliances and conveniences, etc?
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Mar 3, 2018 04:01
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Typical off grid home uses about 4-6 kwh/day. This is key, understanding your daily household energy consumption. A system to support the high end of that would have at least qty 16 L-16 sized batteries. They weigh about 110# each and have a footprint of 8" x 11" by 18" tall, roughly. That is about $6000+ in batteries, and they will last 6-8 years if you take care of them and do not neglect them. You can also get fewer, bigger, industrial batteries that cost a lot more, but also last a lot longer 12-15 years. Newbies to battery care may want to consider a training wheel set first. Maybe a 2000+ watt total array size to support the 6 kwh/day, more or less depending on where you live. You can get qty 9 300 watt panels for a sweet array nowadays, panels cost about a $1 per watt, so that is $2700. "60 cell" panels that size measure roughly 66" by 39". Weigh about 45 lbs. "72 cell" panels measure 77" by 39" and weigh 50 lbs. Roughly. Overall a system that size, just hardware and shipping costs, no install costs, will cost around $15,000. A well done off-grid home will have a balance of energy sources to run it. A wood burning stove is standard for heat. Propane for stove/oven, water heater, clothes dryer, wall heating unit, etc. Back-up generator for occasional large loads and battery charging in winter/cloudy times. A well done off-grid home has all the comforts and amenities of any other home, just with a broader approach to its energy solutions. Internetjack fucked around with this message at 04:26 on Mar 3, 2018 |
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Mar 3, 2018 04:23
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Aunt Beth posted:Do you run an off the grid house just like an on the grid one in terms of consumption? This is a good question. There are some loads you should just skip trying to power with an off-grid solar electric system; its just too expensive. Anything that heats; electric stove, electric water heater, electric clothes dryer, should all be done with some other energy source, typically propane. Air conditioners fall in the same category. This one is a tough one, cause besides fans and swamp coolers(only in dry climates) there are no viable off-grid solutions across the board. Removing these huge energy suck loads from the electrical equation reduces the household energy consumption from a national average of 30 kwh/day, down to an off-grid household using 4-6 kwh/day. They still use the same amount of energy off the grid, they just use a more appropriate forms based on the application.
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Mar 3, 2018 04:34
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Internetjack posted:A system to support the high end of that would have at least qty 16 L-16 sized batteries. They weigh about 110# each and have a footprint of 8" x 11" by 18" tall, roughly. That is about $6000+ in batteries, and they will last 6-8 years if you take care of them and do not neglect them. You can also get fewer, bigger, industrial batteries that cost a lot more, but also last a lot longer 12-15 years. Newbies to battery care may want to consider a training wheel set first. When you say "they will last 6-8 years" is that "to the point of still being sufficient battery for the expected load", or are they just essentially hosed at the end of that time? Wondering if there's like a half-life sort of thing going on where if you have the space you can keep your 16 old batteries that are now as good as 8 new batteries, and add 8 new batteries to get back to the original capacity, so as to have diminishing ongoing costs.
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Mar 3, 2018 16:59
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roomforthetuna posted:That seems expensive, at like $1000 a year in battery replacing alone. My grid-only electricity bill costs less than that. Yeah, off-grid solar is not cheap. The battery sets account for a good 40% of the system cost and it is a repeating cost too. The cost makes sense if you want to live in a remote location, and its too expensive to bring in utility power. Or' some people justify the cost simply by the "autonomy" factor. It never pencils out to take a household with utility power and try to switch it to being off-grid simply because you want to stick it to the vultures at the power company. The ROI is going to be well over 20 years. Utility power is cheap, and for the most part reliable. A golden rule in the world of battery care is to not mix different batteries, or the same batteries of different ages into the same battery bank. Different batteries have different capacities, different charge and discharge rates, etc. Mixing batteries is bad for all of them, some get overcharged and some get undercharged routinely, thereby accelerating the aging of all the batteries. Your brand new batteries will only last as long as what the older batteries have left in them. Its a great way to burn through money, mixing different batteries. Once batteries are put into service they begin to age, after a year they are considered sufficiently aged to be different than a brand new build of the exact same model, so they are different batteries at that point, so don't mix them. The useful life of a battery set is determined by the system owner, essentially when the batteries are no longer holding a charge to keep the TV on for a movie or some such annoying factor. When you are charging them all the time with your solar and genny and they are dead the next morning, most people will be getting a new set. A healthy system takes care of itself essentially, with a monthly maintenance check things plug along just fine. When you start spending most of your free time trying to keep your system and house limping along, then its probably time for a new battery set. Edit: A typical battery bank sizing guideline is to provide 3 days of daily usage, during periods of no sun/solar charging, before the batteries get to a critically low point of 50% state of charge. This gives at least two days of comfortable operation on a new set of batteries before back-up generator needs to be run etc... When this 2-3 day comfort zone has diminished to 1 day or less, because the batteries are getting old, most folks will be ready to buy a new set. Internetjack fucked around with this message at 23:06 on Mar 4, 2018 |
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Mar 3, 2018 18:24
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Internetjack posted:The ROI is going to be well over 20 years. I thought 20 years was about the ROI on just the solar panels, which also last time I looked only have a viable life of about 30 years (has that gotten better?) It's always frustrating to me that there isn't anything low-maintenance in the world. 
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Mar 4, 2018 03:05
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Historically on older panels power production degraded about 1% per year. After 30 years, the panel still produces 70% of its originally rating and is otherwise perfectly fine. Lots of folks, as their power needs grow over time will build a second array and let the first older array keep chugging along side by side with the new array. Nowadays you'll see degradation numbers on spec sheets of 0.6% per year, so panels can be operationally effective for quite a long time. Edit: regarding maintenance and ownership of a an off-grid system; yeah you gotta do it I can't stress enough how important it is for an owner to take ownership of their off-grid system. Its not good enough to just hire an electrician to install an off-grid system and then poke at it with a stick occasionally like its some strange creature living in your house. You'll have poor system performance and an overall bad experience with solar most likely. Instead, you gotta own that beast from start to finish. Read your owner's manuals, follow the advice you are given, pay attention. You do not have to design every single aspect and wire of your household electricity. Ownership isn't in the design, its in the operation and maintenance. That is where new owners need to focus their efforts, and it is a long term focus. Done right means learning to verify your batteries are getting a full charge; learning to adjust your charging equipment to do better if needed. Doing monthly and yearly checks, from simple 5 minute checks to 15 minute thorough checks, to half-day end-to-end checks. When you are off grid it is your system. You are the power company. Own it. If you do not want to do that or can't; then that type of off grid energy system may not be for you. Internetjack fucked around with this message at 23:36 on Mar 4, 2018 |
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Mar 4, 2018 17:06
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Internetjack posted:Edit: regarding maintenance and ownership of a an off-grid system; yeah you gotta do it I mean I'd hate having to mow my solar panels or whatever too, but it really bothers me that literally replacing half the system is something you have to do so often. It's like if we had to rebuild two walls of a house every few years. Though I suppose the roof of a house kind of already is not much better than that, with typical lifespans of 20-30 years.
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Mar 5, 2018 02:29
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I went off-grid for the first time in 2015 when we moved to Hawaii to build. We contacted a company that sold us basically a disassembled "DIY kit". While the inverter/main panel was mostly pre-wired I had a fuckton of electrical learning to do to get it all connected and without dying to boot, so I feel ya when you say you learned a lot of poo poo you didn't know beforehand. The first time we fired it up it was pretty magical to be pulling power from the day-star. We're running 9x 265w Q-cell polys in 3 strings of 3 into our combiner box. We mounted them above our deck like a sun-shade, which is great so they are out of the way and give us partial shade on the deck so we can lounge under them. Definitely want to get 3 more panels soon. We've also got the Midnite Classic charge controller with a Magnum Energy true sine wave 4400 dual inverter (due to having alot of electronics, we wanted to be safe and make sure we had a solid inverter). We've wired in 8x Trojan L16's (lead-acid) in 48v series which gives us a fuckload of juice enough to run basically our fully loaded 2-bed house. We have full sized fridge, run all the tvs/puters etc as normal. Burn about ~20% to 25% nightly, but we never dip below 75% drain. Equalize and top-off the water levels on the first of every month etc. During the cloudy/raining days we run a 6500w genny and can top off the batteries in about ~2 hours usually. Way plenty of power. In total we paid ~$10,500 for the full system and self-installed it. Which was about 1/5th of what it would have cost us to get a half-dozen power poles run down the dirt road to our land and connected to the grid. We've already pretty much paid it off in full so by the time year 8 or so rolls around, we'll have money banked to replace/upgrade whatever. Interesting story however: One night around 1:30am I wake up to the smell of burning electronics and massively thick electronic smoke inside the house. Power's out. I freak the gently caress out that the house is on fire and run down stairs in my underwear to check that something didnt explode etc. I get down stairs and the top of the inverter is bellowing smoke like mad, front of the thing has a red light on and im going OH loving gently caress. I rush over flip the breakers all off and make sure there's no actual fire. After about 2 hours i pass out on the couch. Few hours later in the morning, i pull the inverter box off the wall, crack it open to see what happened... the AC/DC conversion circuit board is got a massive arc-burn across it... In one of the DC terminals i see two fried gecko skeletons, black and crispy like ash. Apparently they got into the inverter, chased each other while they bridged the connection and took the full DC blast. Thankfully my unit was under warranty and I was able to get the $650 circuit board replaced plus labor at no cost. I got loving lucky on all counts with that. Since then we've taken precautions to screen the vents and seal up all holes... but jesus gently caress was that scary. The maintenance is actually really easy, its just daunting at first and if something goes crazy, you better know enough to troubleshoot it. Slayerjerman fucked around with this message at 08:33 on Mar 5, 2018 |
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Mar 5, 2018 08:22
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Slayerjerman posted:two fried gecko skeletons, black and crispy like ash. That's pretty decent they warrantied for something that wasn't a manufacturing defect. Magnum is a younger company but is known for good customer service. Some of the older companies get "Corporatized" as they get older, the bean counters get in charge, and the quality of customer service can go from top-notch, bend-over backwards, to "let me read the owner's manual to you over the phone" level of useless. I've pretty much heard of all small animals getting fried around solar systems. Cats trying to dance on top of the battery bank never ends well. And apparently shrews are EVERYWHERE! Your system sounds like its working well. If you haven't been logging your SG reading in a notebook, you should! Its pre-emptive care, and will let you see emerging patterns of failure as the batteries get older, letting you make system decisions sooner than later, nipping problems in the bud, rather than after they develop to a catastrophic level, to get the most of the battery set.
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Mar 6, 2018 03:17
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Internetjack posted:That's pretty decent they warrantied for something that wasn't a manufacturing defect. Magnum is a younger company but is known for good customer service. Some of the older companies get "Corporatized" as they get older, the bean counters get in charge, and the quality of customer service can go from top-notch, bend-over backwards, to "let me read the owner's manual to you over the phone" level of useless. Nope, I'm lazy and don't log anything anymore after the first 6 months we got it running. I just follow our monthly maintenance routine mostly and keep things clean and filled. I used to take readings daily but gave up with that a while ago :/ Yeah I know preventative maintenance is good, it's just it's an extra thing I rarely remember to do. Heh. I'm sure it will come back to bite me in the rear end eventually. We only just recently put up a battery box enclosure to keep kids/pets from touching the bank... I'm such a dumbass and should have done it on day 1. I am so thankful nothing bad happened.... Jesus Christ.
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Mar 6, 2018 06:34
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I have somewhat regular access to "scrap" 24V 40AH SLA batteries. These batteries seem fine for off-grid solar to me. They're rated 40A and they'll supply at a C1 rate for 50 minutes or a C2 rate for 110 minutes. They're also rated to discharge to 20.0 V (24V nominal) 10,000 times. I know they'll happily do 20*C1 a couple of times an hour if charged at 10*C1 or better. (Yes, they'll output 800A for 10-20 seconds, and then charge at 400A for 30-90 seconds before dropping down to 20-40A charging for 10-90 minutes). How smart does my battery management system have to be to incorporate free-to-me batteries of this type? I realize that having mixed batteries in a string is not so great, but these are $3000 batteries I'm getting for free. What kinds of current draw and depths of discharge are typical in off-grid solar? Does breaking down these batteries into individual cells or 12V/6V batteries make sense? babyeatingpsychopath fucked around with this message at 08:07 on Mar 10, 2018 |
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Mar 10, 2018 08:03
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With those batteries, is it impossible to extend the lifespan on them by replacing consumables? I know literally nothing, but I thought you could change the fluids and metals in them.
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Mar 10, 2018 12:37
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Lord Windy posted:With those batteries, is it impossible to extend the lifespan on them by replacing consumables? I know literally nothing, but I thought you could change the fluids and metals in them. They're sealed lead-acid. There aren't any consumables. Some models have two 12V "blocks" inside, but those blocks are sealed. We're using the batteries in what's typically considered a pretty aggressive high-performance application, and I'm just curious as to whether or not these "retired" batteries are still good enough to be put out to pasture in a solar bank instead of a recycling center.
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Mar 11, 2018 00:36
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That's a question I was wondering about recently - when batteries go for recycling do they meaningfully/significantly contribute to a new batch of batteries? I was thinking about the sudden growth of electric cars, and what's going to happen in 7-10 years when suddenly all these new batteries come due for replacement at about the same time, possibly at the same time as more new cars are also needing new batteries - I hope someone has thought ahead about the likelihood of a sudden-ish almost doubling of demand.
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Mar 11, 2018 05:19
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OP I'm interested in looking after batteries. You mentioned draining your battery bank down to 50%. As in, 6-7 volts for a 12v battery? That can't be good for it. And Hawaii goon mentioned charging his batteries from a generator in two hours. Does charging a battery so quickly damage it?
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Mar 12, 2018 10:13
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babyeatingpsychopath posted:I have somewhat regular access to "scrap" 24V 40AH SLA batteries. These batteries seem fine for off-grid solar to me. They're rated 40A and they'll supply at a C1 rate for 50 minutes or a C2 rate for 110 minutes. They're also rated to discharge to 20.0 V (24V nominal) 10,000 times. I know they'll happily do 20*C1 a couple of times an hour if charged at 10*C1 or better. (Yes, they'll output 800A for 10-20 seconds, and then charge at 400A for 30-90 seconds before dropping down to 20-40A charging for 10-90 minutes). You'd have a battery bank consisting of "a lot of little pieces" versus "fewer larger pieces" to build out any typical amp-hour capacity you normally see in off-grid homes. A guideline in laying out battery banks is to keep the number of parallel strings in the bank to 2 or 3 at most. Too many parallel pathways provides slightly different current flows along each string. Small differences accumulate over time, and the strings end up aging differently, which is bad for all the batteries. Using some of those numbers as an example, you could build a 400 ah battery bank at 24 volts by putting 10 of those in parallel. This is a smallish battery bank by normal off grid standards. You could build the same battery bank with qty 4 L-16 batteries in a single string. Also, your battery bank uses 18 interconnect cables, mine uses 3. Cabling need to be checked thoroughly at least once a year for tightness and corrosion, and I have a slightly easier job than you. Used batteries can be a gamble. If your source is getting rid of them because they were used hard and are due for replacement, you could be getting something with very limited lifespan. Often though telephone companies and hospitals can be sources of batteries that were mostly used in reserve capacity, and by law, have to be swapped out every two years. These are often a great value due to the limited usage. So, how knowing how the batteries were used affects the decision. I'd say go for it if you want to use the batts in a basic system with no great expectations, something for a couple years, a hobby system, something non-critical, go for it. It's hard to argue against a good deal on batts if the application isn't mission-critical. If you're building a system to run a household, something you want to have confidence in, and not be source of headaches, I'd say skip them.
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Mar 12, 2018 14:32
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roomforthetuna posted:That's a question I was wondering about recently - when batteries go for recycling do they meaningfully/significantly contribute to a new batch of batteries? The lead in batteries is pretty valuable, and is looked for by recyclers. MK battery/Deka Battery out of Pennsylvania boasts a pretty major recycling plant for traditional battery types. I forget the exact numbers, but its well over 90% of the product that comes in gets re-used. This is Not a trivial effort on their part. This is a major operation with lot of sophisticated processes going on. One of their biggest hazards is contamination, getting a battery of the wrong chemistry mixed into the wrong recycling chain. I don't know about recycling Li-Ion batts much. They're just coming into play in the off-grid market so haven't paid as much attention to them yet. The metals are precious though, so there has to be some amount of recycling going on there. It would be a question of how sophisticated the recycling operation has to be to see if its worthwhile. The economics of course, drives the priority of recycling.
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Mar 12, 2018 14:43
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Vaginal Vagrant posted:OP I'm interested in looking after batteries. You mentioned draining your battery bank down to 50%. As in, 6-7 volts for a 12v battery? That can't be good for it. 50% of the spread I presume. So if a lead acid battery is (simplistically) 13v charged and 11v discharged then you target 12v for the cycle. In theory they are monitoring core temperature to not charge them too quickly. Hopefully.
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Mar 12, 2018 16:41
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babyeatingpsychopath posted:I have somewhat regular access to "scrap" 24V 40AH SLA batteries. These batteries seem fine for off-grid solar to me. They're rated 40A and they'll supply at a C1 rate for 50 minutes or a C2 rate for 110 minutes. They're also rated to discharge to 20.0 V (24V nominal) 10,000 times. I know they'll happily do 20*C1 a couple of times an hour if charged at 10*C1 or better. (Yes, they'll output 800A for 10-20 seconds, and then charge at 400A for 30-90 seconds before dropping down to 20-40A charging for 10-90 minutes). In theory you're going to need to recondition the batteries and set them up in strings of "as close as possible." Are they high quality name brand batteries (i.e. Deka) that have been properly cared for under a maintenance contract or does whomever is scrapping them abuse their batteries and pay through the nose to replace them constantly? Internetjack posted:If you have questions about what off-grid solar systems are comprised of, what they typically cost, what it takes to operate them, blah, blah, blah; fire away! Post a picture, BOM.  I'm interested in your energy storage, distribution, and non-solar generation. I dream of one day DIY'ing a grid-tied (please don't hurt me) PV array with storage. I've learned enough to be really wrong on the internet about these things through osmosis from my dad. I'm hoping the permitting process gets easier and a standard design comes on market for wiring.
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Mar 12, 2018 18:00
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Vaginal Vagrant posted:OP I'm interested in looking after batteries. You mentioned draining your battery bank down to 50%. As in, 6-7 volts for a 12v battery? That can't be good for it. 6-7 volts is such a stupid question that it becomes a great question. It indicates you are on a path of learning. Congrats! Battery Voltage as a indicator of State of Charge (SOC) is an entire chapter of discussion on its own. The TL:DR version is that battery voltage sucks as a measure of gauging SOC. At room temperature of 77F, At Rest, a fully charged twelve volt battery will ready 12.6 to maybe 12.7 volts, typically. But a voltage of 12.1 volts is a 50% SOC! Keep in mind that 50% is considered critically low for the longevity of a battery. So a difference between 12.7 volts and 12.1 volts (AT REST, AT 77F, critically important details there) is the difference between good and bad. That is 0.6 volts. Most instrumentation will disagree by 0.1 volt with the next meter (often more, varies with a dozen factors), so which one do you believe? The difference is a swing of at least 10% in SOC, which is a huge swing when making decisions on how to operate a system. That said, a seasoned system operator can glean some decent info from a voltage display they have used for years, but that typically comes with hundreds of hours of system operation experience. Also, and this is where the topic of voltage as a gauge of state of charge explodes, you may notice how I mentioned "At Rest" a couple times above. Voltage when batteries are not at rest conveys an entirely different set of information, little of it reflecting SOC. The normal time when a battery bank is at rest is the same time you are; at night, thus you are not even awake at the right time you lazy bum. During the day, a battery bank is typically charging, thus the voltages will be higher/changing all day long. After sunset a battery bank will settle to a resting state, because there is no longer an incoming source of power. But!, you then turn on electrical loads in the house, TV, lights, etc, and that can dip the battery bank's voltage. The heavier duty, and the longer the loads run, the heavier the dip. When you turn the loads off, the voltage recovers a bit back to the resting state voltage; unless you totally drained the poo poo out of them cause you hate batteries. This discussion goes on for another hour, but consider the TL:DR. Battery voltage is a lovely way to judge state of charge. Edit: another MAJOR point in voltage readings as an indicator of SOC is temperature. It cannot be ignored. At colder temps than 77F, voltages read falsely high; above 77F voltages read falsely low. In conclusion: you're an idiot if you only use voltage readings to judge the health of your system. Hawaii goon's appropriate genny run time and charge rate will be different than everyone else's. Even people with the exact same hardware living right next door to him will need different amounts of generator time; cause that is how poo poo works. (That's another TL:DR summary, another dozen variables to consider). Internetjack fucked around with this message at 02:24 on Apr 3, 2018 |
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Mar 13, 2018 03:51
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H110Hawk posted:In theory you're going to need to recondition the batteries and set them up in strings of "as close as possible." Are they high quality name brand batteries (i.e. Deka) that have been properly cared for under a maintenance contract or does whomever is scrapping them abuse their batteries and pay through the nose to replace them constantly?
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Mar 13, 2018 23:14
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On a spectrum of battery types, you can have automotive batteries at one end, and deep cycle batteries at the other. Automotives are designed for cold cranking amps (CCA). A big, short burst of energy to quickly turn an engine over, and then is immediately brought back to full state of charge by the engine's electrical charging system. Deep cycle batteries are designed to be modestly discharged for short periods, overnight or even a day or two, before being returned to full state of charge. A fundamental design difference is in the thickness of the lead plates. The more plates you cram in the battery, the higher its energy storage capacity, but the thicker you make the plates, the longer the battery lasts. These are two design criteria that compete for the allocated space of the battery. Automotives tend to have more, thinner plates; while deep cycles tend to have fewer, thicker plates. It's a spectrum though, and somewhere in the middle you also have RV/Marine batteries that are a compromise for a bit of both effects. I'm familiar with Concorde's SunExtender AGM batts. Concorde has lots of product lines though. They publish C20, C100, etc. AH ratings on the SunExtender spec sheets. In general, you can extract higher C-rates based on smaller number, ie the the C20 will have a higher value than the C10, the C100 will have a higher value than the C20, etc. So, you ~could~ look at a C1 or C2 and guesstimate a higher C20 value. (BTW, most of the off-grid solar industry uses the C20 rate as the benchmark for the sake of discussion). BUT! Why didn't Concorde publish a C20 or C100 rate for that particular battery? They publish those rates for the SunExtenders, right? My guess is because they don't consider the battery as the best recommendation for a C20 application. They have other products for that niche. Just a guess on my part. It doesn't mean the batts won't work, its just not their first pick. Again, if the price is right and the mission is not critical, it can't hurt to give them a go. You could potentially have $3k of batteries serve you for a couple years, or at worst, you are paying to haul someone else's garbage.
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Mar 14, 2018 00:15
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So what the hell am I running? Household is hybrid. I have utility power, a battery based solar electric system, and a back-up generator for my household electricity. The house was built with all this in mind. Why utility? Because it's cheap, reliable, and essentially the world's biggest back-up generator. At least where I live. Utility power prices in Hawaii and some other places is stupidly, but justifiably, high. Where I live, it's cheap. Also, there was a utility run along the edge of the property that had minimal cost to tap in to. I did Not have to pay to pull power all the way to my property from a half mile away or anything crazy like that. Having utility power lets me run energy hog loads like electric space heaters that would never be feasible in the cost of a pure off-grid system. Monthly bill is about $45-$50. I could crank it up to 6X that though if I didn't use a wood burning stove for heat, and propane for cook-stove and water-heating. What's the solar stuff for then? For a degree of autonomy. I've separated my household load circuits. The solar electric system directly powers key critical loads such as the refrigerator, well pump, ~some~ of the lighting, a few outlets, and a few other mission critical items. The solar system collects power in the panels, stores it in the batteries and runs these loads directly. The rest of the household loads are on a separate utility-only panel. Here is a key point though: the solar system is backed-up by both utility and generator power. So how does that all work? Think of half the house being on solar, and half on utility power. The essential stuff like the frig is solid, it can be powered by the solar energy, the grid energy, or the generator. During a utility blackout, I do lose power to my non-critical loads. All the key stuff, including my computer, satellite internet are all kept running just fine, and seamlessly. This lets me posts my garbage on SA during the worst of the seasons. Hooray for us. I also have water pressure, lighting, and a working frig too. The solar system can sustain those loads indefinitely for the most part, being backed-up by the genny if needed. Hardware porn: Power room has a Xantrex XW6048 inverter, Power Distribution Panel, with their XWMPPT80-600 charge controller, and the System Control Panel for the interface. The XW line is now owned by Schneider Electric, and you'll see it referred to as the Conext XWPlus product line. The inverter is now the XWP6848 etc, blah, blah. I use a Trimetric 2025 as my battery bank monitor. I have a single string of Trojan L-16RE-B. Trojan just revamped their product names, so now its called some other name. The array is qty (8) REC 200-something watt panels in a single series string (refer to the charge controller mentioned above) on a pole mount about 200' from the house. About 1700 watts total. Both the battery bank and array are not all that much. Battery bank is essentially the minimal recommended size by Xantrex/Schneider to run the show. I did this for cost. I do not have infinite piles of money to draw upon. This set is totally suitable and should last another 3-4 years. Then I'll probably go with 2X-3X the capacity on something industrial for the longer lifespan. Battery box and space in the power room was planned with this in mind. The array is a testament to my awesome genius. Not really. I just kinda played with a couple numbers one day. The series string of 8 panels creates a higher voltage array, which allows the power to transmit over the 200' efficiently on smaller gauge wire. The XWMPPT80-600 is a high voltage charge controller that is designed for higher voltage arrays. Also, it has a much higher capacity than I am running it at now, so I can build on the array in the future. This is also a "planning ahead thing". Down the road I will build a second array of similar size, right next to the first array. I've sized the combiner box at the first array, and the wire run to the house with this expansion in mind. My pre-planning lets me add the new array in the future with no real changes/overhauls to the rest of the system. One last thing; I do not sell back to the grid. The array is not big enough to justify it. I use pretty much everything I collect. I'm also not interested in jumping through the extra hoops the utility company requires to sell back. They care very much if you want to sell back, and it's important they do. They don't really care at all if you are just a user though.
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Mar 14, 2018 01:31
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Internetjack posted:
I did the thing also what do you think of this business: https://www.youtube.com/watch?v=cNbsiZcwGSY I don't see anything like this even possibly working where it gets chilly out, I have no faith. Honestly I'm pretty unhappy with my lovely solar panels situation, I feel like if I wanted to have electricity in the cold months I would have to bore a hole into the very core of the earth if I wanted to passively keep the batteries safe. Then again all I really know about bats is you're not supposed to freeze them, and if use them when it's very hot or cold they'll probably break.
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Mar 28, 2018 03:47
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SniperWoreConverse posted:Head over to Ask/Tell, I started an Off-Grid thread there a couple weeks ago, I think its on page 2 now. Repost there, I'll hit you up with some answers. I did the thing also what do you think of this business: https://www.youtube.com/watch?v=cNbsiZcwGSY I don't see anything like this even possibly working where it gets chilly out, I have no faith. Honestly I'm pretty unhappy with my lovely solar panels situation, I feel like if I wanted to have electricity in the cold months I would have to bore a hole into the very core of the earth if I wanted to passively keep the batteries safe. Then again all I really know about bats is you're not supposed to freeze them, and if use them when it's very hot or cold they'll probably break. Edit: Internetjack is too stupid to know how to quote properly, my reply starts below this line!  Operating temp is something very much worth considering when looking at batteries. In general, it is better to operate them in an environment with ~some~ amount of warmth in cooler climates. (also, warm environments, where the batteries routinely see higher temps like 90F are insanely bad for battery longevity, and can reduce lifespan of flooded lead acids by as much as 30%) In general, most battery types that are at 100% state of charge (SOC) will not freeze until somewhere around -70F. BUT! A battery at 50% SOC can freeze around -5F. Freezing can crack cases, shove plates out of alignment shorting them out, etc. You want to keep them at or near fully charge anyway though, so typically freezing isn't a huge issue of concern. Also though, battery's energy storage capacity is de-rated at cold temperatures. They store less energy when they are colder. It's a temporary effect, the capacity comes back at warmer temperatures, but this effect is worth considering. Again with the car gas tank analogy: Say you have a 30 gallon gas tank, and you use 5 gallons every day. You are discharging the tank by 15% every day. Not bad. In cold weather though, your gas tank magically shrinks to 20 gallons. Now your 5 gallons a day is discharging the battery bank by 25%. That's a bit heavy. So the same amount of energy usage is running the batteries harder during the colder temps. You can expect them to not last as long as "typical". I had some co-workers run their batts, good old flooded lead acid L-16s, in an un-heated out-building for years. They knew what they were doing for care and maintenance, but we guesstimate that they typically saw a year less life span. Not great, but also not the end of the world. Battery spec sheets typically call out operating temperature ranges. It's a spec well worth looking at. Deka's gel batteries have the widest temp rating I'm familiar with; check out this typical spec sheet: http://www.mkbattery.com/images/8G4DLTP-DEKA.pdf -76F!!!! Holy poo poo, that is extreme. The above effects still apply but that is the lowest operating temp I've seen on a spec sheet. It's still worth keeping them "warmer" somehow, cause they will simply last longer. That can be insulating the battery box, painting it black, putting it in a root cellar, etc. It doesn't have to be 77F, but something at 40F to 50F will serve you a lot better than running them at 20F. At the other end of the spectrum, the various Li-Ion technologies have the tightest temperature operating ranges. It's one of the reasons you hear about Li-Ion fires; they are typically operating them incorrectly at non-spec temps. There are a few different Li-Ion technologies, but for the most part they need to operate at more normal "room temperature" temperature ratings. Once you have batteries that are no longer holding a charge like they use too, its typically time to replace them. If you took good care of them, hopefully you got good life. If you took lousy care of them, then its too late, damage has already been done. You can always check maintenance, tightening and cleaning cabling connections, doing very, very, very controlled correctional charges, and you might squeeze some more life out of them. Its worth the college try and all that, but don't spend too much time on it, cause it may just be time for a new set. Recycle your old batts if there is a recycling joint in your county. You may get $5-10 each! Enough to buy some beer and pizza maybe. Or you could burn them in a bonfire, huff the fumes, probably poison yourself, start a uncontrolled fire, and toxify your land. That is always an option. Just give them to a battery joint for no cash is better than anything else. Take that DIY video with a grain of salt. That guy obviously knows what he is doing; just look at the organization of his shop, the quality of his finished work, etc. He has put in a lot of time and learned from it. He does joke about a couple of explosions/fires though. That guy is NOT your typical DIY though. Old school DIY like him were hard core, and essentially built the industry from the ground up. They used their brains and figured poo poo out, and didn't whine when poo poo went wrong. Most modern day DIYer are not like that guy at all. They are very much "I saw youtube video, so that means I can do things just as well" and they have never touched a soldering iron in their life. Especially with lithium technology. Holy poo poo, lithium is cool stuff, but its the most energy dense battery tech on the mass market these days. Dynamite is also an energy dense technology. Done wrong, things can go wrong on a much greater scale than ever before possible! Its a great time to be alive, and suicide yourself cause you are actually a clueless gently caress that has no business handling this stuff in your garage. Just buy a professionally engineered product already. I have nothing wrong with smart DIYers that know the risks, its pretty admirable. Its just that most people don't have the time, inclination, and dedication to learn a tech on the scale that that guy has. Lastly; just cause a battery froze, does not necessarily mean its destroyed. Likely? Yes! But there is still a modest chance they are okay, once thawed out. Do NOT try to use a frozen battery. You must let them thaw first. Seems obvious, but I get that question a few times each winter. Bizarro. Once thawed, check voltage, check for leaks, check water levels if possible, etc. Proceed with caution, do not proceed if not comfortable. Test them with a small load, or very light charge. Make sure they don't start getting hot. Don't leave them unattended, etc. I've heard plenty of frozen = dead cases, but also a very few cases of it working out okay and batteries continuing to work for several more years. Internetjack fucked around with this message at 02:19 on Apr 4, 2018 |
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Mar 28, 2018 05:20
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fuuuuck that battery is a beast that one battery probably weighs more than my entire system (I was using it to basically charge my phone, run some lights, and was about to set up a little ventilation fan thing) goddamn. I'll dig out the hosed up battery and see if I can mess with it some when it gets warm, maybe I can get something out of it. It sucks poo poo that they cost so much but you only get a couple bucks out of scrapping them. Although it's not like it's platinum in there or something, it makes sense that the actual value would not be in the cost of raw materials.
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Mar 28, 2018 05:49
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SniperWoreConverse posted:fuuuuck that battery is a beast This is where system sizing comes into play. What is a properly sized battery for your application? The batt I linked has a total capacity of 12 volts x 183 amp-hours = 2196 watt-hours. Watt-hours is a good metric for system sizing discussion/comparison. Kind of a most-common-denominator thing. What does 2196 watt-hours mean to you? Let me write some fiction where I estimate your power consumption based on your description. Cell-phones take jackshit to charge, low power load compared to everything else; barely registers. "some lights" I'm going to assume is some LED lighting. I'll pretend it's three 5 watt bulbs averaging 5 hours a day each. Power consumption is a total of 15 watts x 5 hours = 75 watt-hours per day (whrs/day). A little computer vent fan may draw 5 watts too. If its 24 hours/day then that is 5 x 24 = 120 whrs/day. Add that up and its about 75+120+cellphone = 195+ whrs/day. 250 whrs/day would be a highball estimate on this example. Obviously you can plug in your own wattage and run time numbers here for a specific analysis. For the example though, let's compare 200 whrs/day to a battery that stores 2196 watt-hrs total. On a cloudy day of no charging, that would be a bit less than a 10% discharge. That's pretty gentle and the battery would do well in that application. Highest cost option. You can choose smaller gel batteries that cost less, that would be discharged more. You could choose a marine battery at 12 volts and ~100ah rating. That battery with 200 whrs/day would be more like a 17% discharge. Marine/RV batteries cost a lot less, but may only last 2-3 years. Lowest cost option. You could buy a pair of flooded lead acid golf cart batteries for a config of 12 volts and 225 ah = 2700 whrs. Price would be halfway between the gel battery and the Marine cost. Medium cost option. Sealed batteries are nice and all, for simple systems though, sticking with practical solutions would be my recommendation. The Marine or the golf cart in this case. Lastly, this is all a made up example. If you have actual wattage numbers, and daily hour of run time for your loads, we can develop a more accurate picture and recommendations. Internetjack fucked around with this message at 07:25 on Mar 28, 2018 |
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Mar 28, 2018 07:14
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If you aren't pursuing sales to industrial facilities, you should. The factory I work for has put in three 1kw systems to run lights in various corners of our parking lot because it's still cheaper than trenching concrete.
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Mar 30, 2018 17:53
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Oh cool an off grid thread! We've just bought some land in central Victoria, Australia to build a first house. It will be off grid (probably li-ion) and the intention is to go all electric with heat pump hot water and induction hob with a wood burner as primary heating. We could go bottle LPG for cooking but I'd rather not unless we have to. The climate is pretty amenable, we should get a pretty good solar yield and don't get ridiculous winters like you get in the US (though it is a cold location by Australian standards). Looking about $40 - 45 k for an off grid system that allows for about 10kwh per day. The land was affordable because an on grid connection will cost about the same as the off grid system, which makes the economics viable. We're in the design phase of the house at the moment - the house will be simple, small and as energy efficient as possible. I
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Mar 30, 2018 22:58
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Tomberforce posted:heat pump hot water and induction hob heat pump hot water...? I'm not sure what that is. Is that a geothermal heating thing? If so, double check the size, run-time, and power consumption of the pump. Geothermal systems often use 2 to 5 HP pumps that can run up to 12 hours a day in the colder seasons. That can add up to a LOT of power consumption. Don't do your cooking with electric heat elements unless you only cook once a week or something. Do the propane stove. Price seems a bit high, but not horrible. Does it include installation cost? If so, and whatever the exchange rate is, that might be perfectly reasonable. The cost of materials and shipping for a system to support 10kwh/day in the states would be more around $25k. Professional installation may be another $5 to $10k. Congrats on taking on a new adventure. Re: commercial Where I work we do a fair amount of smaller commercial systems, some sign lighting stuff, some critical load support, some vanity projects. The bigger stuff is usually getting bunch of bids, and it becomes a waste of time for smaller companies. Large scale systems are all about the bidding war, who can offer the cheapest $$ solution. Takes a lot of time and effort for minimal profit. It's a lot simpler for a small company to focus on residential scale where the profit margins are better, and our expertise in system design and support is more valuable to the end user. Internetjack fucked around with this message at 04:55 on Mar 31, 2018 |
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Mar 31, 2018 02:19
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Internetjack posted:heat pump hot water...? I'm not sure what that is. Is that a geothermal heating thing? If so, double check the size, run-time, and power consumption of the pump. Geothermal systems often use 2 to 5 HP pumps that can run up to 12 hours a day in the colder seasons. That can add up to a LOT of power consumption. With heat pumps, this is the specific unit: https://www.sanden-hot-water.com.au/how-a-sanden-heat-pump-system-works I know these are run in off grid setups here in Australia and are apparently extremely efficient. The general idea is that they heat the water during the day with the solar, which is banked overnight. Not sure if they have these systems abroad? Our winters will occasionally dip to about 25 degrees F over winter, but not too often. It's generally a bit warmer. There seems to be some conflicting stuff out there about the viability of Induction cooktops. I know a normal electic cooktop wouldn't fly, but some people seem to be successfully running induction cooktops off grid? They use very little energy but have a high peak demand when they're first turned on. I'd love it if it was viable, but yeah LPG is the fallback option there!
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Mar 31, 2018 07:50
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Before we got our LP range we ran two table top induction burners off our system, they draw like 1200w each at 100% setting. Fine for heating up a can of chilli or soup. You would absolutely not want to cook a full meal or anything that takes a long time on those... A standard 2-slot electric toaster consumes like 800w over 5mins. God help you if you're feeding a family and need to run it a lot... we don't have or use a microwave anymore either... Heating with electric is why people have huge power bills. Heating with gas is cheaper and far more efficient and won't wreck your system... whenever we need to use a lot of electricity for power tools or heavy loads we always augment with our generator and never draw heavy usage after dark. Slayerjerman fucked around with this message at 10:10 on Mar 31, 2018 |
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Mar 31, 2018 10:07
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Tomberforce posted:With heat pumps, this is the specific unit: https://www.sanden-hot-water.com.au/how-a-sanden-heat-pump-system-works This comparison page shows some kwh numbers: https://www.sanden-hot-water.com.au/hot-water-heat-pump-system-comparison Table at the top shows 265 kwh being used in 93 days, so 2.8 kwh/day. The chart at the bottom shows 1250 kwh/year, I think. That's 3.4 kwh/day. I'd factor in at least 3.0 kwh/day in my energy budget to run one of those. Slayerjerman's post above is spot-on for off-grid system operation. You can run those big loads for very short periods of time, periodically, no problem. You just don't want to get carried away. Internetjack fucked around with this message at 02:54 on Apr 4, 2018 |
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Mar 31, 2018 22:38
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consider solar thermal heating as well. That can be done DIY relatively easily and you avoid the losses caused by converting it to electricity. I somehow feel like a heat pump would use it or just extract heat out of the air itself which I think might be less efficient. I wouldn't completely rely on solar heating only, i'd at least want some kind of wood stove.
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Apr 1, 2018 08:47
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SniperWoreConverse posted:consider solar thermal heating as well. That can be done DIY relatively easily and you avoid the losses caused by converting it to electricity. I somehow feel like a heat pump would use it or just extract heat out of the air itself which I think might be less efficient. I wouldn't completely rely on solar heating only, i'd at least want some kind of wood stove. Yup plan is for a woodburner next to a reverse brick veneer wall for thermal mass. Not familiar with solar thermal heating - is that like hydronic but using solar hot water to heat the radiators? Has anyone designed a new house specifically with off grid in mind?
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Apr 1, 2018 22:15
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there's a couple different forms but I don't have all the super in-depth links I used to have on hand anymore. I was heavily into this a few years ago but wasn't able to pursue it for various reasons. 1: a bunch of black tubes in a case. You put this in the sun, it absorbs heat even in winter. Then you redirect the coolant to radiators, or a hot water tank to store the heat, or potentially pipe it into a heat pump system so that you can do things like store the heat in the earth during summer and bring it back out in winter (probably only worth it if you can't get enough heat in winter just from the array). This needs electricity for the pumps. Because it's not a pressurized system you could use an old hot water tank and not hook up the heating element, or you can actually build your own tank. I don't know enough to be able to effectively compare storing the heat in a tank vs storing it in the actual ground through a heat pump, except that the tank would probably be much cheaper than a heat pump. Probably if you tried to hook it to a heat pump it would have to be done professionally, if it's even possible to design a system like that. I think it could work well but honestly I dunno and lost a lot of the info I had researched. 2: instead of black tubes it's possible to put this case on the south facing wall of your house, then use a system of baffles. This lets the regular air in the house itself act as the medium for heat transfer. It's obviously less effective than water or coolant, but it's completely 100% passive because the heating action also moves the air through the house. Sort of like how the old coal furnaces ran nonstop and it was a very gentle warming system. This only works when the sun is hitting the panel, and it actually has to be on the south wall of the building. It'd be potentially cheaper and easier to set up and maintain, but I'm not able to do it because I would have to remove a porch and gently caress that I'm keeping my drat porch. If I knew an easier way to set this up I would have tested it myself already. I might take off the siding and cut up the second floor of my house for this over the summer and see how it works next winter. This involves cutting various holes from the living space to the outside of your house much more extensively than running pipes like in #1. There's a lot of good information and bullshit idiots talking about this stuff. Check out this goofy web 1.0 site: http://www.builditsolar.com/index.htm also with wood burners I know they have chimneys that are either enameled metal or fully ceramic, and that might be super effective at radiating stored heat when you aren't actually burning. I have no experience with them though but it might help get just a little bit more out of every log you burn, assuming there's a portion of the chimney that's inside the living space.
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Apr 2, 2018 08:29
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I do ham radio stuff, and was gifted a radio tower last fall. I've thought over what i want to do with it, and i plan on putting it on a piece of property up on the hills in the valley i live in. Pretty exited honestly now that spring is arriving. I'm decent at 12v systems and batteries, since that's what all my radios run off of, but haven't done anything with solar before, so hopefully i can get enough advice to figure out how to go about this, or better yet, tell me what a dumb idea it is and just stop. The location is too far from civilization, so off grid it is. Not a bad thing since i want it running even if there's a disaster that kills local power for a few days or weeks. I plan on putting all kinds of things on the tower a bit at a time. But for the sake of the panels and batteries, i'm going to plan ahead and invest in everything the system would need power wise even if its not drawing that much to start. The math i'm doing prepares the system for a constant 10 Amp 12V DC draw, so 240 amps a day.The whole system will be running 12v DC. I'd like enough reserve power to run 3 days of no charging, in case of cloudy weather or snow. I get about 4-5 hours of peak sunlight which i'm sure is important to consider. So far, i think i have a pretty good idea what i'm doing. But my big concern is weather, and the environment the batteries are going to be in. We get all seasons in full force here. Temperatures range from minimum -20f to maximum 110f. There is nothing in the field i'm putting this all in, so no shed or house to keep the batteries from freezing. I read the above discussion mentioning colder temperatures and freezing batteries, but could i get some advice more specific to my case? What should i put together to store the batteries in an open field? An insulated box of some kind, or would it be smarter to bury them? If they are buried, how should i combat snow/ice/rainwater? I don't want to come inspect the batteries to find them in a pool come spring. And taking into account that low voltage batteries risk freezing, just how big should the bank of batteries be to combat that?
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Apr 2, 2018 11:42
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notanarsonist posted:I do ham radio stuff Daily power consumption: 10 A x 12 VDC = 120 watts, running 24 hours/day = 2880 whrs/day to support. Battery bank; using a guideline of the daily load taking 3 days to discharge the batteries to critically low at 50% => a factor of 6, so battery bank size is 2880 x 6 = 17,280 whr battery bank to support the daily load. It's a 12 volt battery bank, so 17,280 / 12 => 1440 Ah battery bank at 12 volts would be your sizing goal for the bank. For your application I'd look at the Concorde SunXtenders first. They are AGMs, with decent cycle life. They also have some higher capacity products to pick from. Product list: http://www.sunxtender.com/specifications.pdf Technical manual (btw: this tech manual is one of the more interesting reads on AGMs in general): http://www.sunxtender.com/pdfs/Sun_Xtender_Battery_Technical_Manual.pdf The tech manual temp specs: -40F to 160F. You could use qty 6 of the 6 volt 405 Ah PVX 4050HT to get a bank at 1215 Ah and 12 volts. A bit shy of the goal. They also have a few other options, you could do qty 12 of the 2V batts, two parallel strings of something like PVX 6720T to get 1344 Ah, etc. Array for 2880 whrs/day should be minimum 700 watts, but likely more depending on where you live, and if you want winter operation. 900-1400 watts will serve most places in the USA, and something like 2000 watt array would probably be useless overkill. Build a nice box for the batts. Put a couple inches insulation in the walls, lid and base if needed. Internally, leave a half inch of room between batteries and walls for air flow. Paint it black (maybe?: great for winter, lousy for summer!). Make the roof sloped to shed snow, etc... You could bury them deep to pick up some geothermal heat, but that might be a hell of a lot of work for only a marginal performance gain. If you want to favor preserving the batteries over the system running 24/7, ie it is Not mission critical, you can use a low voltage disconnect device that will disconnect power to the loads if battery voltage drops too low. The equipment gets shut off until voltage recovers, but it does so to preserve the batteries from getting slammed. A lot of old-school charge controllers can do this. Look at the Schneider C-35 as an example. It has two potentiometers to set the disconnect and reconnect voltages precisely where you want them. BTW: controllers like this can work as a Solar Charge Controller, or a Diversion Load Controller, or a Low Voltage Disconnect device; but it can only do one of those. You'd still have another charge controller regulating the panels charging the battery bank, and use the C-35 as the low voltage disconnect separately. After initial installation, you'd want to fine-tune the setups a bit, having it turn off early enough to preserve battery life, but not so early it's shutting the system down when it doesn't need it. Definitely get the temperature sensor accessory they make for the controller. Internetjack fucked around with this message at 06:53 on Apr 3, 2018 |
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Apr 3, 2018 02:12
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