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Marchandiso
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# Posted: 21 Jan 2014 04:53pm
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Hi, I've been reading quite a lot on different forums and websites about this but I'm still feeling the need for advice. Hope you guys can spare some time for this.
I have a 16X16 cabin with a 8X16 mezzanine and small attic. It's mostly used on weekends and occasional weeklong holidays. I want a little solar setup for the convenience of charging cellphones, portable radio and lighting needs, nothing more.
Power need:
8 X 7W (0.6aH) 12V led lights (http://ledmontreal.com/en/led-light-bulbs-gu10-mr16-e27-par20/7w-12v-dimmable-e27-le d-light-bulb.html)
For the cellphones, I'll take my 2100maH S3 battery as base so roughly 2amps if fully discharged.
Radio has a 3400maH Li-Ion battery so 3.4amps.
So, once in a blue moon, my power need should be 3 charges (2 cell and 1 radio) and 6 lights on for 6 hours (assuming the attic lights are off) for a grand total of 36.2aH.
On a normal day, I should consume about 10 to 15aH (3 lights for 6hours and a cellphone charge)
The Setup:
A cheap 20W solar panel (model GS020-12M) http://www.canie.com.cn/en/ProductView.asp?ID=15
A basic 6A charge controler http://addison-electronique.com/catalog/product/view/id/17157/s/solsum-6-6f-controleu r-de-charge-solaire-12-24v-6a/category/293/
A small (300W) lighter socket inverter
A 110aH 12V car battery (as I can get one for free)
I have two concerns : time of charging the battery should I discharge 36amps out of it and having that kind of battery inside the cabin as I have read about fumes and explosions hazard. The woodstove is centraly located so there's no getting around that.
I'm getting a fair amount of direct sun in the summer time (until 2pm). Winter is another story.
Did I miscalculate or forget anything?
Any comment would surely help!
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ChuckDynasty
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# Posted: 21 Jan 2014 05:20pm - Edited by: ChuckDynasty
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There is a handy off-grid calculator here:
http://www.altestore.com/store/calculators/off_grid_calculator/
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Dillio187
Member
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# Posted: 21 Jan 2014 05:21pm
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you need more solar panel. a 110ah battery likes to be charged around 10-12 amps, and your 20W solar panel is around 1amp. The year-round average for good daily sunlight is 4 hours. You would need to replenish that 36ah in 4 hours, so you would need a minimum of 9amps of charge current to do that. The reason you want to charge the battery back up as soon as possible is that they can get build up on the plates if left discharged for too long, ruining the battery.
One other thing to consider, the cheap lighter socket inverters are MSW (modified sine wave) and some things don't like that wave form. Computers are OK, but I've seen issues with LED bulbs. I see your want to use 12V LED's so this may not be an issue. They also tend to be less efficient due to the wave form.
Others may disagree, but I would not worry about fumes from the battery. You would have to boil several batteries that size dry to even generate enough hydrogen for an explosion, and you would have to do it in a short enough time to allow the hydrogen to build up. I have 4 golf cart batteries in my garage at home, and 2 golf cart batteries in my cabin, and it's never been an issue. If you still worry about it, you can put your battery(ies) in a box and run a small vent tube out the side of the cabin.
Let me know if you have other questions, I've built a few of these systems here in Minnesota and love to help others get going in off-grid solar.
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Marchandiso
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# Posted: 21 Jan 2014 06:16pm
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Well that's not convenient... That's pretty much the info that I was missing: How many amps are needed to charge a battery.
Now, knowing that I need a lot more amps to charge that battery, what are my options to keep the price as low as possible? What kind of battery can charge on low amperage? What are my solar panel options?
Thanks for the help, it's much appreciated
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silverwaterlady
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# Posted: 21 Jan 2014 06:23pm - Edited by: silverwaterlady
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I can't help you with solar.I don't know how far you park your vehicle from your cabin. I charge my cell phone in the truck along with the hand held marine radio we listen to each morning for the weather report. I also have a inverter and charge bigger things with that when we are driving to town.
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VTweekender
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# Posted: 21 Jan 2014 06:25pm - Edited by: VTweekender
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I think if you go up to a 80 watt or so panel, and leave everything else you have in place you would be fine, 80 watt panel would get you about 16 amps a day on good days, just don't let your battery go below 50% charge or you will ruin it in a hurry,....keep that metered.
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Marchandiso
Member
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# Posted: 21 Jan 2014 07:14pm
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Quoting: VTweekender I think if you go up to a 80 watt or so panel, and leave everything else you have in place you would be fine, 80 watt panel would get you about 16 amps a day on good days, just don't let your battery go below 50% charge or you will ruin it in a hurry,....keep that metered.
That option's not bad. It would be 100$ more give or take. I was hoping to keep the whole thing under 200$ (battery not included) but I guess I'll have to put a bit more on the table.
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ChuckDynasty
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# Posted: 21 Jan 2014 07:43pm - Edited by: ChuckDynasty
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I'm experimenting with a small system to see what I can do with it and what my needs will be.
I like all 12v stuff if possible as I don't like to use a power inverter. I'm using a 50w Instapark panel (very short run...matter of a couple of yards) to charge a Sun Xtender AGM sealed deep cycle 108amph battery to run a couple of led lights and a 10" 12v LCD tv daily. I have a sunsaver 10 charge controller which I can use with a larger 145w DM Solar panel I also have but am not currently using to charge everything quicker If I need or want to.
I can charge small batteries for my short wave radio, and flashlights with a Rayovac battery charger that has a 12v car adapter, I can charge cell phones, tablet, iPod, BaoFeng radio etc. with the cig type sockets device usb port. I only use a power inverter to run my laptop.
My Coors Light-Light is 4w LED aimed at ceiling and the light bounces off the white ceiling and light colored walls very nicely and I can easily read with this small light on. I also have a 1.5w under the cabinet light strip that I converted into 12v and that is sitting on top of the headboard pointing at the ceiling as well. I use this light when I watch TV so I'm not watching TV in too dark of a room. Both lights are separately switched at my bedside and I don't use them at the same time.
I have my tv hooked up to a home made OTA (over the air) antenna which is in my attic and cost about $10 to make. I get 25 plus channels ABC, CBS, NBC, Fox, PBS and others I don't care too much about most stations are 20 miles away and the furthest 49 miles away.
I will go from a fully charged 13v battery to no lower than 12.5v if I use laptop and in the summer I'd be recharged pretty much the next day with a good sunny day. Now it would take several days. Without using my laptop I go down to 12.7 or so.
For me the smaller the better for several reasons.
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Just
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# Posted: 21 Jan 2014 07:53pm
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180 amp hr. deep cell ,Wall Mart battery @ 99$ a better choice, not the best choice but much better than a car battery at that price .THATS what I have with 60 watts of panel , we are very happy with it !!!
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Dillio187
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# Posted: 21 Jan 2014 11:38pm
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check out solarblvd.com for good prices on individual 12V panels, I haven't found much else in the same neighborhood (the DM solar panels mentioned above are good too and can be found on Amazon). A Solar Cynergy 120W panel will set you back $132 plus shipping and get you a maximum of 7amps charge current in perfect conditions. Real life conditions will be less than this.
As mentioned above, try ditching the power inverter and run everything direct from the battery. Most phones and computers have 12V car chargers available, and then spend the extra money on a bigger solar panel.
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toofewweekends
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# Posted: 22 Jan 2014 02:15am
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I am no electricity whiz, but I'd guess your max power use is high. You're more likely to top off cell phones and such that run them to zero and need a long charge. Check at home if they charge off the inverter. My phones, cfl lights, radio, dvd, computer all do fine with modified sine. We charge a couple of golf cart batteries with a 90w panel. Fine for weekend use as it gets several days to catch up. We top off with a charger running off a generator in winter and long stays. If you're going to run any power tools or charge cordless ones, you might end up with a generator anyway.
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Marchandiso
Member
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# Posted: 22 Jan 2014 09:38am
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Quoting: ChuckDynasty I'm experimenting with a small system to see what I can do with it and what my needs will be.
Nice setup you got there Chuck! I'll be looking into smaller wattage for my lightbulbs. Maybe a couple of amps less may take me a long way. Every wall and ceiling are painted white at the cabin to get maximum brightness.
Quoting: Just 180 amp hr. deep cell ,Wall Mart battery @ 99$
Thanks for the tip, I'll check if we have something similar in Quebec. Might be worth the investment.
Quoting: Dillio187 As mentioned above, try ditching the power inverter and run everything direct from the battery. Most phones and computers have 12V car chargers available, and then spend the extra money on a bigger solar panel.
I didn't know that they made 12V chagers for cellphones. I'll be looking into that today, thanks! The radio charger is a two pins AC though...
As for the pannel I'll be checking the ones you mentionned out. Maybe I can get them here as the shipping could run me up quite a bit.
Quoting: toofewweekends I am no electricity whiz, but I'd guess your max power use is high. You're more likely to top off cell phones and such that run them to zero and need a long charge. Check at home if they charge off the inverter.
I'm no electricity whiz myself though I learn more and more everyday... My max power should not be that high. I know inverters are powerhogs but since it'll be used to charge one item at a time, I guess it won't surge that high. As for the rest, only lightbulbs will be running on the battery.
I have a woodstove and I plan on making some ecofans to circulate the heat. These would look something like that but I can make them for less than 20$
http://www.instructables.com/id/DIY-Stove-Fan-for-under-50/
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Dillio187
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# Posted: 22 Jan 2014 09:52am
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I didn't catch that you were in Quebec. Yea, unfortunately you guys get ripped off when importing things from the US, that's too bad really.
You could check to see if there is a 12V adapter or charger for your radio. If it plugs into the wall with a wall wart/transformer there likely is.
Anyways, keep us up to date on what you end up with and how its working for you. Good luck!
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Just
Member
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# Posted: 22 Jan 2014 10:58am - Edited by: Just
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Quoting: Marchandiso something similar in Quebec
In Ontario here,I got all my stuff local at CTC. OR WALMART LIKE YOU I STARTED with a 20 amp panel one battery and a small inverter.worked ok but I soon learned the less I used the inverter the better, make sure you turn off the inverter when not in use!!We now use 12 volt for everything but power tools,
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Marchandiso
Member
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# Posted: 22 Jan 2014 11:21am - Edited by: Marchandiso
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Quoting: Just In Ontario here,I got all my stuff local at CTC. OR WALMART LIKE YOU I STARTED with a 20 amp panel one battery and a small inverter.worked ok but I soon learned the less I used the inverter the better, make sure you turn off the inverter when not in use!!We now use 12 volt for everything but power tools,
Plan is to work everything straight out of the battery and use the inverter strickly to charge the phones/radio so it shouldn't be used or even plugged in that much. That's why I want to get a car lighter socket and small inverter... Keeps things small and affordable. As far as powertools go, I can get a generator up there when need be... it's hard work though!
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Marchandiso
Member
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# Posted: 22 Jan 2014 11:26am - Edited by: Marchandiso
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Quoting: Dillio187 Anyways, keep us up to date on what you end up with and how its working for you. Good luck!
Will do!
I'm still in the planning part and I should be installing the setup in april.
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bldginsp
Member
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# Posted: 22 Jan 2014 11:40am
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Dillio- (or anyone else)-
Is there a good book or website that focuses on design of off grid systems like this? Preferably something that explains all the different components carefully and shows how to come up with the best combination of components given specific needs?
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Marchandiso
Member
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# Posted: 22 Jan 2014 11:43am
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Quoting: bldginsp Is there a good book or website that focuses on design of off grid systems like this? Preferably something that explains all the different components carefully and shows how to come up with the best combination of components given specific needs?
Can we post link to similar topic websites on this forum?
If so, I can give you a bit of information I collected over the past few weeks.
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Dillio187
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# Posted: 22 Jan 2014 12:28pm - Edited by: Dillio187
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Quoting: bldginsp Is there a good book or website that focuses on design of off grid systems like this?
I did a lot of reading at NAWS Forum. I think I read back through every page in the off-grid section. Lot's of great information there. They go over it time and time again, you plan your system backwards from the amount of power you expect out of your system. It really helped me in designing my cabins system, and also provided a ton of great ideas in equipment, wiring, safety, panel mounting etc. I couldn't recommend it any more. Be warned, it took me almost a month to read all of the back topics, but it was well worth it.
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CabinBuilder
Admin
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# Posted: 22 Jan 2014 12:36pm - Edited by: CabinBuilder
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Quoting: Marchandiso Can we post link to similar topic websites on this forum? If so, I can give you a bit of information I collected over the past few weeks.
Sure, assuming it is relevant, specific and is not a plain spam.
If general links only, perhaps the Useful Links and Resources section is more appropriate. Otherwise, whichever topic is relevant.
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bldginsp
Member
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# Posted: 22 Jan 2014 12:40pm
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thanks Dillio. I was hoping for a single book that tells me what I want in straightforward form, but maybe that's a dream. I'll check out the site
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Marchandiso
Member
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# Posted: 22 Jan 2014 12:52pm
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Thanks!
Quoting: bldginsp Is there a good book or website that focuses on design of off grid systems like this?
It may not be a homerun but it's relevant information to get started.
So here's what I kept over past 2 weeks.
A small wrap up on solar power.
http://www.freesunpower.com/faq.php
Information about batteries
http://batteryuniversity.com/
http://www.solar-electric.com/deep-cycle-battery-faq.html
http://www.backwoodshome.com/articles2/yago88.html
http://www.backwoodshome.com/articles2/yago87.html
Information about inverters
http://www.backwoodshome.com/articles2/yago89.html
http://www.donrowe.com/power-inverter-faq-a/258.htm
http://www.photonicuniverse.com/en/how-to-choose/ac-inverter/
Now that I see what I've kept, I guess it's time to start researching on solar panels.
Hope this helps
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Dillio187
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# Posted: 22 Jan 2014 04:35pm
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Quoting: bldginsp thanks Dillio. I was hoping for a single book that tells me what I want in straightforward form, but maybe that's a dream. I'll check out the site
I'm sure they are out there, but a single author has their own ideas and goals on what is right and wrong. I loved the forum because I got to see dozens of working systems, and commentary on what worked, and what didn't, for them.
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mago
Member
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# Posted: 7 Feb 2014 04:06pm
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I have a small cabin 14x32 I wired the cabin like a camp trailer. Having DC and AC power with solar coming into the cabin. Works great ! I have a generator that runs all of my cabin off of AC things like lights, microwave,TV and radio. When I am not using the generator I have a converter that runs DC to run lights, and radio. Now I deciede to put in solar as well to run everything in my cabin when I don't feel like running the generator .. All systems work great. If you would like to know more about this system please let me know.
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RMP
Member
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# Posted: 8 Feb 2014 07:52am
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Dillio...
Good to hear you say that keeping a battery inside will not be a problem. I've been agonizing over that. I have a small but solidly constructed cabin I built myself in 1992 and I'm just now getting around to wiring it.
I'm going to stick with the simple is better maxim....12 volt. I just received a 100 watt solar panel and charge controller and will be acquiring a 100 AH AGM battery that I want to install on the floor just below my electrical hub panel for the fuse box, volt/amp meter, charge controller, etc.
Now that you've put my mind to rest I can proceed with placing the battery inside. I'm a stickler for safety and doing things right.
Thanks....
Glad I found this site, by the way....
RMP
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Truecabin
Member
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# Posted: 9 Feb 2014 11:09am
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Marchandiso
>>Plan is to work everything straight out of the battery and use the inverter strickly to charge the phones/radio so it shouldn't be used or even plugged in that much.
are you aware that a car phone charger is 12v?
charge your phones same as in your car
if you have a cig lighter socket in your cabin unplug the inverter and charge the phone with 12v directly i bet the inverter wastes enough power to charge 2 phones
i was doing about same as you and 80w was ok but not great
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Marchandiso
Member
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# Posted: 19 Feb 2014 03:45pm
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Quoting: mago I have a small cabin 14x32 I wired the cabin like a camp trailer. Having DC and AC power with solar coming into the cabin. Works great ! I have a generator that runs all of my cabin off of AC things like lights, microwave,TV and radio. When I am not using the generator I have a converter that runs DC to run lights, and radio. Now I deciede to put in solar as well to run everything in my cabin when I don't feel like running the generator .. All systems work great. If you would like to know more about this system please let me know.
I'm always open for advice!
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Marchandiso
Member
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# Posted: 19 Feb 2014 03:48pm
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Quoting: Truecabin are you aware that a car phone charger is 12v?
No, I thought these things were small inverters...
So the inverter might only be needed to charge off the radio.
The plan is to install a cig lighter socket so because I don't need that much AC power and a small cig socket inverter will do the trick.
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Dillio187
Member
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# Posted: 19 Feb 2014 05:06pm
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most cell phones charge with 5VDC, so a car adapter is a 12v to 5v step down adapter. Most laptops run on 19VDC so they use 12v to 19v step up transformers.
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skootamattaschmidty
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# Posted: 19 Feb 2014 07:02pm
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I have also purchased a number of items from ctc. This week they have a 40 watt panel on for $99 regularly $269. Comes with a 7 amp PWM charger and a number of connections. Have you also considered the power packs they sell. These have a 12v plug built in as well as built in inverters with 120 receptacles. The coleman solar panel can be plugged directly into them. This obviously is a small system but affords some portability. Prior to buying our cabin we used one of them for camping. It ran all the lighting and water pump and I had a 15 watt panel plugged directly into it. When the sun couldn't keep up, this unit could be plugged into the 12v in the car to charge up. Just another option.
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