Posted: 5/12/2014 10:19:29 PM EDT
| Those of you who have solar systems, what type of batteries do you use to store the charge? I just bought a Coleman, 55 Watt, 12 Volt generator w/a 110 invertor. Now I need to decide what type battery...and I'm not versed in solar power. . |
For getting the best bang per buck, it's pretty hard to beat golf cart batteries.
They're built more ruggedly than most "RV/Marine/Trolling Motor" batteries, yet don't cost any more - Sam's Club and Costco both sell 'em for around 80 bucks apiece. Since they're 6 volt batteries, you'll need to use them in pairs (connected in series) in order to get 12 volts. |
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For getting the best bang per buck, it's pretty hard to beat golf cart batteries. http://imageshack.com/a/img843/3097/mwaq.jpg They're built more ruggedly than most "RV/Marine/Trolling Motor" batteries, yet don't cost any more - Sam's Club and Costco both sell 'em for around 80 bucks apiece. Since they're 6 volt batteries, you'll need to use them in pairs (connected in series) in order to get 12 volts. I just finished installing two 120 watt panels and two Sam's Club golf cart batteries in my father in law's race car trailer. They power the hydraulic lift for the trailer, the winch to get cars on and off, lighting, and occasionally some tools like s drill press, grinder, and small air compressor. So far the system is working great. ETA: I talked him into the solar setup because the trailer only used one small starter battery. He was killing them frequently and it was getting expensive. This was without using them to power and inverter and all the 110 things like lighting and the tools. Now the system is much more versatile and self sustaining. We just need to watch the fluid level in the batteries. |
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For really small systems, a 30AH sealed-lead-acid.
For smaller systems, golf cart batteries are the way to go, Trojan 105's are my preference. And for big systems, Rolls/Surrette are the way to go. My BOL is on year 15 with the same set of monster Rolls batteries. |
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My house runs primary power from a series string of 2 Volt ROLLS lead acid cells.
1590 Amp-Hours, arranged in a 24 volt bank. Secondary string of DEKA 6 volt, 370 Amp-Hour L16 for back-up. Usually leave them in parallel most of the winter, and the DEKA rest in summer. |
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My house runs primary power from a series string of 2 Volt ROLLS lead acid cells. 1590 Amp-Hours, arranged in a 24 volt bank. Secondary string of DEKA 6 volt, 370 Amp-Hour L16 for back-up. Usually leave them in parallel most of the winter, and the DEKA rest in summer. Are there any issues running such lopsided banks in parallel? |
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For getting the best bang per buck, it's pretty hard to beat golf cart batteries. http://imageshack.com/a/img843/3097/mwaq.jpg They're built more ruggedly than most "RV/Marine/Trolling Motor" batteries, yet don't cost any more - Sam's Club and Costco both sell 'em for around 80 bucks apiece. Since they're 6 volt batteries, you'll need to use them in pairs (connected in series) in order to get 12 volts. Why not just use one 12v battery? Also, how do you connect them into a series? Like I wrote, I know as much about solar power as Zero does on the economy (or foreign affairs or the Constitution or internal affairs or stopping illegal scandals in his administration or...). |
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Why not just use one 12v battery? Also, how do you connect them into a series? Like I wrote, I know as much about solar power as Zero does on the economy (or foreign affairs or the Constitution or internal affairs or stopping illegal scandals in his administration or...). Quoted:
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For getting the best bang per buck, it's pretty hard to beat golf cart batteries. http://imageshack.com/a/img843/3097/mwaq.jpg They're built more ruggedly than most "RV/Marine/Trolling Motor" batteries, yet don't cost any more - Sam's Club and Costco both sell 'em for around 80 bucks apiece. Since they're 6 volt batteries, you'll need to use them in pairs (connected in series) in order to get 12 volts. Why not just use one 12v battery? Also, how do you connect them into a series? Like I wrote, I know as much about solar power as Zero does on the economy (or foreign affairs or the Constitution or internal affairs or stopping illegal scandals in his administration or...). The 6V batteries are far more rugged than a 12V battery, and with two you get twice the total power stored v. one 12V. Basically the 6V are the same size as a large 12V, but they're only 3 cells so the cells are bigger, as are the plates and everything about the construction, which makes them live longer. Series is easy, you just need a short jumper, and you connect the "+" post of the first battery with the "-" post of the second, this leaves you with the "-" post open on the first battery and the "+" post open on the second, and they're at 12V, and you connect that to your 12V system. This is a very common setup in the 12V power world (RVs, small solar power systems, etc.) |
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Why not just use one 12v battery? Also, how do you connect them into a series? Like I wrote, I know as much about solar power as Zero does on the economy (or foreign affairs or the Constitution or internal affairs or stopping illegal scandals in his administration or...). It depends on your power needs, a couple of plain old 12 volt deep cycle batteries are what most people use in RV's. I have a standalone emergency lighting system in my cabin, it consists of just a few RV-type light fixtures scattered about the place, and wired to a single marine deep-cycle 12 volt 100 ah battery, the lights all have LED bulbs in them, so if I turn all of them on I am drawing less than 15 watts of power to light the whole place up, I could run them 24 hours a day for a couple months before the battery ran out of charge. So for that application it's perfect, I could plug in a couple of 12 volt accessories here and there too and still have it last a while, and re-charge it with the genny in an hour or so now and then. If I hooked a small solar panel to it and didn't run the lights 24 hours, it would probably never run down. But if I tried to hook up my fridge (having attached an inverter obviously), it would die pretty fast, within a day or so, and no way a 50 watt solar panel would keep up to re-charge fast enough. For heavy draws you need big storage, there's also the matter of start-up surge on some things, which takes big inverter power. Inverters are inefficient too, especially at low current draw, they actually have higher efficiency when you are running them hard, but at low current draws you may be giving up over 70% of your power. My rule of thumb therefore is: Running nothing but 12 volt accessories? then a 12 volt marine deep-cycle might do, two work great. Running AC stuff? You need big battery storage, big panels, and big inverters. |
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Your Coleman array will produce 3.6 amps in ideal conditions. Not nearly enough to recharge the big deep cycle batteries some guys are talking about in this thread. I have two Trojan T-105s (6V wired in series) and my 158W panel is undersized for them. I plan on getting two more panels to match my battery bank better.
A 5-13% charging rate is generally recommended when matching panels to batteries. So a 55W array that produces 3.6 amps means a battery capacity of 28 to 72 amp hours. For your 55W array you should just get a 12V 35ah sealed battery like this. Anything bigger and you're likely to chronically undercharge it if you use it regularly, reducing battery life considerably. Don't expect much from a 55W array + 35ah battery. What are you hoping to do with this system? |
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Your Coleman array will produce 3.6 amps in ideal conditions. Not nearly enough to recharge the big deep cycle batteries some guys are talking about in this thread. I have two Trojan T-105s (6V wired in series) and my 158W panel is undersized for them. I plan on getting two more panels to match my battery bank better. A 5-13% charging rate is generally recommended when matching panels to batteries. So a 55W array that produces 3.6 amps means a battery capacity of 28 to 72 amp hours. For your 55W array you should just get a 12V 35ah sealed battery like this. Anything bigger and you're likely to chronically undercharge it if you use it regularly, reducing battery life considerably. Don't expect much from a 55W array + 35ah battery. What are you hoping to do with this system? First off, thank you for warning me off the bigger batteries. It sounds like I should get a couple of the smaller ones you show and, what is the term, put them in a "parallel?" The system would be asked to do very small items. Help recharge flashlights and cellphones, run/recharge a laptop, recharge those self-enclosed systems you see at Wal-Mart that are a multi-in-all (air compressor, light, battery pack w/a plug in like your car cigarette lighter and regular AC plug in), and run some lights at night. If it can run a small television, great. I also wonder if it could run a small fridge. |
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First off, thank you for warning me off the bigger batteries. It sounds like I should get a couple of the smaller ones you show and, what is the term, put them in a "parallel?" Quoted:
First off, thank you for warning me off the bigger batteries. It sounds like I should get a couple of the smaller ones you show and, what is the term, put them in a "parallel?" You could put two of these small batteries in parallel but then you start running into the same problem I was warning you about, too much battery, not enough solar. Two of these batteries would put you at a ~5% charging rate. Acceptable if you're only using the system on occasion for small stuff. Too low if you're drawing the batteries down to 50% daily. It would take 4.9 hours to recharge two of these 35 ah batteries from a 50% state of charge in ideal conditions using your solar panels. In the real world you'll be lucky to charge them in a day. Sizing your battery bank really depends on your load, how many days of autonomy you want, and other ways you can charge the batteries if solar is limited (generator, grid, etc.). The system would be asked to do very small items. Help recharge flashlights and cellphones, run/recharge a laptop, recharge those self-enclosed systems you see at Wal-Mart that are a multi-in-all (air compressor, light, battery pack w/a plug in like your car cigarette lighter and regular AC plug in), and run some lights at night. If it can run a small television, great. I also wonder if it could run a small fridge. To put this in perspective, a 35 ah battery run down to 50% (the most you should regularly run these kinds of batteries down to) would power a 7W LED light for 20.6 hours, including the inverter draw (based on my little 150W inverter). If you skipped the inverter and ran an RV type fixture (1141 LED) directly from the battery, it would power it for 134.6 hours. This is based on measurements I've made using Kill-A-Watt and Watts Up meters. For recharging AAs, cellphones, etc., I'd skip the inverter and wire the batt(s) with a 12V cigarette adapter---inverters draw power if they're turned on regardless if there's a load connected to them and are generally inefficient. You might even be able to skip the battery altogether for this application, though I've only tried this with a little 4.4W panel. |
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For that small of a setup a small AGM battery will work fine.
You can expect to put about 3.5 amps per hour into the battery for about 5 hours per day (in most parts of the US). So you will put 17.5 amps in, top. That means a 35 aH battery can be discharged to 50% each day and theoretically recharged. The optimal charging rate for an AGM varies but C/8 is not a bad estimate. So your 3.5 amps in this context would be ideal for a 28 aH battery. Close to the 35 aH above. What can this power? The optimal discharge rate is about C/20. So if you have a 35 aH batt then you will get best life pulling about ~2 amps out of it each hour. 2x12v DC amps will run a small Fantastic Fan on low (maybe medium), charge a smaller USB device (not a bigger than normal draw like an IPAD), run an AC inverter rated at 20 watts (laughable), or run a small stereo system (my LeiPei Tripath draws <1 amp most of the time on reasonable volume). You can run such an appliance for about 9 hours per day. If you discharge faster due to plugging in an excessive load, you won't get the full 35 aH (really 17.5 as discussed). If you need to run bigger loads you can get a bigger batt to stay closer to the C/20 ROT but then you run the risk of undercharging the battery with too little solar. You could mitigate that with a Battery Tender Jr running in the background to help keep it topped off if the system is largely for emergency loads. There's no way a fridge will run. Even a Koolatron like truckers use is ~4 12v amps, so you could run that for a few hours before killing the batt. An actual AC fridge will pull something like 2 AC amps which is 20+ 12v DC amps through an inverter (plus more on startup when the compressor spins up). A laptop pulls something like 6A so that might be possible for a few hours. I have 200W of solar with a 100 aH battery and find it to be a better solution for stuff like you want to do. Even so I am not generating enough juice to run the Koolatron 24/7. I might add a second batt at some point, but for now I use a converter to run stuff when plugged in, so the solar just needs to keep things chugging until I can plug into shore power or fire up a generator for a few hours. The solar also works fine on its own for lights/fan/TV/stereo/USB devices. |
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Wanted to point out the lowest prices for panels I've seen...
Link This link is the real deal, I've bought pallets from it's referenced sellers. $190 for almost 250 watts, what's holding folks back from picking up a few? Many dealers ship FedEx for careful handling, and customers pick them up at the FedEx terminal, to avoid rough 'home' delivery. Shippings costs haven't been bad for me. |
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Is this the Coleman unit you bought OP?
From Home Depot For $288? If so, personally, I'd return it ASAP! For many reasons... YMMV |
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The numbers that Cathan91 and Armaboralis are putting out are a whole lot less impressive than the box is, which makes it look like it is big enough to do a small fridge.
I'm thinking I might just return this and do like Expy37 suggested and pick up an individual panel, build a solar panel holder myself, and get the individual parts. That would give me almost four times the capacity. Just out of curiosity, what type of watts do you folks have to run your own homes? That might be down the road for me but, as you can see, I'm new to this. |
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ESPY 37: I paid $229 on sale at Mendards. Based on what I'm reading above, I'm thinking of returning it and buying the system individually as parts (panels, inverter, etc.). I personally would return this system. For the price and what it is, it's less than impressive. Looks similar to the Harbor Freight set, which doesn't have a good reputation for longevity. Of course building your own system will send you spiraling down a rabbit hole, especially if you're starting out from a state of blissful ignorance 
Circuit protection and grounding alone will make you pull your hair out. Then there's determining the correct sizing of the panel array, the battery bank, charge controller, battery charger, generator, wires, inverter, etc., etc., etc. Also keep in mind the great majority of panels available on the market today are designed for grid-tied applications. If you're looking for off-grid solutions you can either get 12V panels and go with a PWM controller, or grid-tied panels and an MPPT controller (much more expensive). There are also 24V and 48V options. I've opted for a basic 12V system, MPPT controllers are out of my price range and for what they cost above PWM controllers you can almost buy another panel. |
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For that small of a setup a small AGM battery will work fine. You can expect to put about 3.5 amps per hour into the battery for about 5 hours per day (in most parts of the US). So you will put 17.5 amps in, top. That means a 35 aH battery can be discharged to 50% each day and theoretically recharged. The optimal charging rate for an AGM varies but C/8 is not a bad estimate. So your 3.5 amps in this context would be ideal for a 28 aH battery. Close to the 35 aH above. What can this power? The optimal discharge rate is about C/20. So if you have a 35 aH batt then you will get best life pulling about ~2 amps out of it each hour. 2x12v DC amps will run a small Fantastic Fan on low (maybe medium), charge a smaller USB device (not a bigger than normal draw like an IPAD), run an AC inverter rated at 20 watts (laughable), or run a small stereo system (my LeiPei Tripath draws <1 amp most of the time on reasonable volume). You can run such an appliance for about 9 hours per day. If you discharge faster due to plugging in an excessive load, you won't get the full 35 aH (really 17.5 as discussed). If you need to run bigger loads you can get a bigger batt to stay closer to the C/20 ROT but then you run the risk of undercharging the battery with too little solar. You could mitigate that with a Battery Tender Jr running in the background to help keep it topped off if the system is largely for emergency loads. There's no way a fridge will run. Even a Koolatron like truckers use is ~4 12v amps, so you could run that for a few hours before killing the batt. An actual AC fridge will pull something like 2 AC amps which is 20+ 12v DC amps through an inverter (plus more on startup when the compressor spins up). A laptop pulls something like 6A so that might be possible for a few hours. I have 200W of solar with a 100 aH battery and find it to be a better solution for stuff like you want to do. Even so I am not generating enough juice to run the Koolatron 24/7. I might add a second batt at some point, but for now I use a converter to run stuff when plugged in, so the solar just needs to keep things chugging until I can plug into shore power or fire up a generator for a few hours. The solar also works fine on its own for lights/fan/TV/stereo/USB devices. Koolatron are far from the most efficient small refrigerators. They use peltiers, which have limited cooling ability and high current draw. Something like the ARB fridges or Engel is much more efficient and can cool all the way down below freezing, even in hundred degree weather. http://store.arbusa.com/Fridges-C11.aspx http://www.amazon.com/Engel-MR040-Portable-Volt-fridge-freezer/dp/B001DE45EY Sure, they are expensive, but they are very efficient and will run indefinitely on a fairly basic solar/battery setup. ETA: There are slightly lower cost options also: http://www.amazon.com/Whynter-FM-45G-45-Quart-Portable-Refrigerator/dp/B002W8BLUG/ref=pd_sbs_sg_5?ie=UTF8&refRID=041D1JSXEZEN7WBRXXF7 |
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I personally would return this system. For the price and what it is, it's less than impressive. Looks similar to the Harbor Freight set, which doesn't have a good reputation for longevity. Of course building your own system will send you spiraling down a rabbit hole, especially if you're starting out from a state of blissful ignorance
Circuit protection and grounding alone will make you pull your hair out. Then there's determining the correct sizing of the panel array, the battery bank, charge controller, battery charger, generator, wires, inverter, etc., etc., etc. Also keep in mind the great majority of panels available on the market today are designed for grid-tied applications. If you're looking for off-grid solutions you can either get 12V panels and go with a PWM controller, or grid-tied panels and an MPPT controller (much more expensive). There are also 24V and 48V options. I've opted for a basic 12V system, MPPT controllers are out of my price range and for what they cost above PWM controllers you can almost buy another panel. Quoted:
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ESPY 37: I paid $229 on sale at Mendards. Based on what I'm reading above, I'm thinking of returning it and buying the system individually as parts (panels, inverter, etc.). I personally would return this system. For the price and what it is, it's less than impressive. Looks similar to the Harbor Freight set, which doesn't have a good reputation for longevity. Of course building your own system will send you spiraling down a rabbit hole, especially if you're starting out from a state of blissful ignorance
Circuit protection and grounding alone will make you pull your hair out. Then there's determining the correct sizing of the panel array, the battery bank, charge controller, battery charger, generator, wires, inverter, etc., etc., etc. Also keep in mind the great majority of panels available on the market today are designed for grid-tied applications. If you're looking for off-grid solutions you can either get 12V panels and go with a PWM controller, or grid-tied panels and an MPPT controller (much more expensive). There are also 24V and 48V options. I've opted for a basic 12V system, MPPT controllers are out of my price range and for what they cost above PWM controllers you can almost buy another panel. If you don't mind my asking, how did you learn about solar? Are you an electrician or electrical engineer? Someone referred me to the "Backwoods Solar Catalog." It has some information in it I'm just now going through. Do you know if these solar power sellers have folks on staff who can help guide you? |
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ESPY 37: I paid $229 on sale at Mendards. Based on what I'm reading above, I'm thinking of returning it and buying the system individually as parts (panels, inverter, etc.). That would be IMO a wise decision... http://www.ar15.com/forums/t_10_17/636169_BOL_Chest_Freezer_Conversion__Solar_Panels__Evaluation_WORKING_GREAT_.html https://www.ar15.com/archive/topic.html?b=10&f=17&t=640246 https://www.ar15.com/archive/topic.html?b=10&f=17&t=585317 |
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want.
EVERYTHING> I'm Just starting out also, is there anyone here willing to mentor a newb? I have budgeted a backup system in the first year consisting of 8 trojan T105's, individual chargers(if necessary) a 2500kv inverter. In year two I'd like to add a 2-3k(200v or 250panels to start off with)solar panel system with charge controllers as the primary source of power and a standby generator for topping off the system when needed. In the first phase I'd like to do a 12 volt system, as it appears to be the easiest way to add 12v devices, lights, pumps and other key components for a emergency backup/shtf equipment. Ultimately, I'd like to go totally off grid with a 24v or higher system. guidance from guys who've live it would be much appreciated. I have a 3- 400$ a month electric bill I'd like to see go to 0 while becoming independent of the system THanks, JJ |
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want. EVERYTHING> I'm Just starting out also, is there anyone here willing to mentor a newb? I have budgeted a backup system in the first year consisting of 8 trojan T105's, individual chargers(if necessary) a 2500kv inverter. In year two I'd like to add a 2-3k(200v or 250panels to start off with)solar panel system with charge controllers as the primary source of power and a standby generator for topping off the system when needed. In the first phase I'd like to do a 12 volt system, as it appears to be the easiest way to add 12v devices, lights, pumps and other key components for a emergency backup/shtf equipment. Ultimately, I'd like to go totally off grid with a 24v or higher system. guidance from guys who've live it would be much appreciated. I have a 3- 400$ a month electric bill I'd like to see go to 0 while becoming independent of the system THanks, JJ I'm not as far as you yet. All I'd like is a mobile system that could do some basic recharging, such as cell phones, and running laptops or a television. You know, the kind of thing that, if there was a regional power disruption that might last for a week or two, that could keep us in flashlights, cell phones, computers, and a television to keep abreast of what is going on. I wonder, does any solar power sales group have a, what would you call it, a blueprint on how to put a system like that together? Or maybe someone here has that type of system and could describe their system. |
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If you don't mind my asking, how did you learn about solar? Are you an electrician or electrical engineer? Someone referred me to the "Backwoods Solar Catalog." It has some information in it I'm just now going through. I'm a farmer, I knew jack about electrical work a few years ago. I've read obsessively about it, but you can't really know what you don't know until you actually build and use a system. I've been living off-grid since November and am currently in the process of expanding my PV system, so I've been even more obsessed about solar than usual. Been a steep learning curve. Backwoods Solar's catalog is a good thing to have, and it's free. Dan Chiras' book “Power from the Sun” has been useful, as has Jeffrey Yago's writings (lots of stuff for free from Backwoods Home Magazine). Northern Arizona Wind & Sun's forum is also an excellent resource, especially their Beginners' forum. Kind of the Arfcom of DIY solar. There are lots of schematics of small off-grid systems, here's a very basic 12V system from one of Jeffrey Yago's articles: 
The very first thing I did when I first started out was to get a Kill-A-Watt meter, which will allow you to measure your 120V loads (anything you plug into the wall at home). Plug your fridge in and see what it draws over a 24-hour period. Do the same with all the other appliances you'd like to run. That'll give you an idea of what your loads are, then you can size your system from there. I wouldn't count on powering your fridge, though converting a chest freezer to a fridge might be an option. I use an RV fridge which mostly runs on propane (<0.5 amp from a 12V battery to power the controller). I wouldn't start out buying a giant battery bank, it's easy to mismanage deep cycle batteries, which aren't cheap. I started out with a slightly used 150 ah AGM deep cycle battery for $100 and beat the crap out of it while I was learning. I recharged it with a multi-stage (Iota IQ4) battery charger and a Honda EB3500 generator. Then I got a single 158W 12V panel and a cheap charge controller, and have been expanding from there. Once I'm done with my current expansion, my system will consist of: --3 Dmsolar 158W panels --2 Trojan T-105 batteries --Morningstar TS-45 charge controller --Sima 150W inverter (smaller is better IMHO, but I also have a 400W Cobra for back up) --Meters: Morningstar charge controller meter, Kill-A-Watt, Watts Up, Extech clamp meter --Various sundry fuses, breakers, switches, bus bars, etc., etc., etc. --Honda EB3500 generator --Iota IQ4 45-amp battery charger Like I said, it's a rabbit hole. Kind of like first getting into guns. Fun and expensive. |
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Quoted: want. EVERYTHING> I'm Just starting out also, is there anyone here willing to mentor a newb? I have budgeted a backup system in the first year consisting of 8 trojan T105's, individual chargers(if necessary) a 2500kv inverter. In year two I'd like to add a 2-3k(200v or 250panels to start off with)solar panel system with charge controllers as the primary source of power and a standby generator for topping off the system when needed. In the first phase I'd like to do a 12 volt system, as it appears to be the easiest way to add 12v devices, lights, pumps and other key components for a emergency backup/shtf equipment. Ultimately, I'd like to go totally off grid with a 24v or higher system. guidance from guys who've live it would be much appreciated. I have a 3- 400$ a month electric bill I'd like to see go to 0 while becoming independent of the system THanks, JJ I wouldn't mind pitching in and trying to help, though you've got a pretty lofty goal. There's a lot of people here smarter than me. I agree w/ Cathan91, the first thing to do it get a kill-a-watt and understand your usage and where your power goes today. Spend a month or two logging data about everything you own w/ a power cord attached to it. In the meantime, read, read, read... |
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I just bought this little kit, it's on sale for the next hour I guess, it's normally $399.99, showing $343.99 currrently OBO, the seller took my offer of $325.00 shipped, I'll start a thread and give a report once I have it in hand. 100 watt monocrystalline panel, 30 amp controller expandable to 400 watts worth at 12 volts or 800 at 24, cable, brackets, and a 1000 watt pure sine wave inverter. Not bad pricing, I still need to pick up another battery or two. Renogy has a good name and feedback from all the links I checked.
http://www.ebay.com/itm/271381533874 |