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setting up solar in a cabin. many questions  RSS feed

 
Pamela Teele
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I have a cabin that hasn't ever been hooked up to a power box. has some elect wires ran in walls to hook up a car battery to. I have purchased a few solar kits. I have one 60 watt 4 panel solar battery charger, 10 amp solar charge controller, a 80 watt 4 panel battery generator, 2000 watt cont/ 4500 watt max inverter. I am trying to get enough power to run a small chest freezer, 37 in flat screen, wii, dvd player, some lamps and possibly an ionic heater if wood stove burns out at night. gonna piggy back 10 truck batteries. New to all this and researching as much as I can but brain is overloaded researching this and reserching/ building a small animal far for my kids. Please help any way possible. trying to cut cost of things I don't need. Thank you
 
Marc Troyka
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Location: East Central GA, Ultisol, Zone 8, Humid
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140 watts is barely enough to power a light bulb, let alone a fridge, TV, and other things. And that would be if the sun shined 24/7. I think you'll need more than that, and a wind turbine might be a good idea to cover for times when it isn't sunny out. I don't really know about the batteries, but the inverter and charge controller sound right. Did you run a ground post? That's very important.
 
Pamela Teele
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grounding? running copper wire over a piece of plywood to 3ft piece rubar as a lighting post to protect the inverter. Will that be enough? I'm not sure the inverter will be enough. can you run 2? I have been looking to add an 1800 watt total home kit. But I'm not sure how much power that will give. Sales people around here have no clue when I ask questions. thank you.
 
Marc Troyka
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Location: East Central GA, Ultisol, Zone 8, Humid
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I don't think you can run two inverters, since they'd have to be synchronized. That could cause all kinds of weird issues, and it wouldn't make sense to run 2x inverters to one bank of batteries anyway. 2kw is a bit low for an inverter if you want to run a space heater, you may need a higher power one.

As long as you use a very large gauge of copper wire and bury the rebar stake most of the way in the ground, that should be fine. Make sure the connection is good and solid.

I think you'll probably want to be pushing at least ~5kW on average, but be warned even the smallest space heater I've ever seen is 2kW* and it'll only keep you warm if you keep it under a blanket to trap the warm air. You might want to check some of your appliances to see just how much they draw.

*I need to double check that
 
Pamela Teele
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The space heater I can do without. I was just going to us it until I could get a mass heater built. There is a wood stove so heat is covered for a little while. I'm just trying to figure out how many solar panels are needed to supply a good charge in the batteries and be able to run a few items my children enjoy. And if I needed 2 of the 1800 watt solar kits. Maybe a good started inverter, but look to purchase a larger one in the future? The small chest freezer is a must, cause I'll have a cooler type fridge that ice keeps cold.
 
Kathy Burns-Millyard
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Location: Arizona low desert
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We just finished upgrading our solar setup today and I'm working on writing a detailed article about it soon. In short, it's a but more complicated than it first looks. The controller is key. Basic ones that come with the kits are PWM controllers, which do not allow you to get the maximum usage out of your panels. An MPPT is MUCH better but also much more expensive.

We used the 60 watt kit for a little over 3 years. Because of the way the controller works, we estimated the system have us about 24-30 watts an hour during peak sunlight. The new system is 100 watts and so far today - with clouds, dust and haze - we're getting about 70 watts an hour. Full sunlight will likely put us very close to or at 100 watts. HUGE difference and I'm thrilled

I'll try to post more details in the next few days as I have time.
 
Pamela Teele
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Kathy Burns-Millyard wrote:We just finished upgrading our solar setup today and I'm working on writing a detailed article about it soon. In short, it's a but more complicated than it first looks. The controller is key. Basic ones that come with the kits are PWM controllers, which do not allow you to get the maximum usage out of your panels. An MPPT is MUCH better but also much more expensive.

We used the 60 watt kit for a little over 3 years. Because of the way the controller works, we estimated the system have us about 24-30 watts an hour during peak sunlight. The new system is 100 watts and so far today - with clouds, dust and haze - we're getting about 70 watts an hour. Full sunlight will likely put us very close to or at 100 watts. HUGE difference and I'm thrilled

I'll try to post more details in the next few days as I have time.


I'm looking forward to reading it. I was wondering what size controller I needed.. I don't want to overload the batteries, but want to get as much usage as I can
 
Glenn Underhill
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Location: NW Montana
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I'm not an expert but I have been doing a lot of reading on this because I will be going off grid soon.

You can sort of estimate what you will need and experiment as you go, but if you want to get a good idea of what you need, you can use an online calculator like this one.

The first thing you do is figure out the watts drawn for each item you want to power. A Kil-A-Watt meter is great for this, they cost $20-30 and you can get from Lowes, Home Depot, or Amazon. If you don't want to get a Kil-A-Watt meter, you can google for estimates on most things. But I recommend the meter, it can be an eye-opening experience and gives you a firm idea of how many watts you use. Keep in mind that a lot of things draw power even when turned off.

Then figure out how many hours per day you run each item. Add it all up and you have your daily watt-hour load.

Enter the daily watt hour load in the calculator and it will tell you what size panel array you need, charge controller and inverter size, and total batteries.

Charge controllers can be run in parallel to double your amps rating, but its best, I think, if they are identical charge controllers. Use the highest voltage you can from your panels to your charge controller because that will reduce voltage drop in longer wire runs from the panels to the controller and allow you to use smaller gauge wire. But use big gauge wire from the controller to the batteries. Deep cycle batteries are best, regular car batteries will be destroyed quickly.

Glenn
 
Kari Gunnlaugsson
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Hi Pamela...just a few thoughts for what they're worth...

If I could just throw a bit of a curve ball at you... when people start to think about living off-grid on solar they often get hung up on thinking about the power supply side of the equation and miss lots of opportunities on the demand side. Not sure if your cabin is going to be a full-time dwelling or a recreational space, but either way I think it could be a really valuable opportunity to shake up your lifestyle a bit.

If I was you I'd hook up the solar stuff I already had for now, and try living with it to see what you really, honestly need.

Like you said, you can skip the heater. If you have good warm bedding and maybe some toques (stocking caps) you'll be just fine when the stove goes out at night, and if it's a fairly small space it will warm up quick with the morning fire. Have fun contests to see who has to get up and start the first one! Huddle by the cozy stove with hot drinks while breakfast is on.

I'll bet the kids will be just fine without the flatscreen DVD player and the wii. Unplug them for a bit and see what happens, it might be awesome for them. Chores and fun things outside, build a fort, get some fun board games / books / art supplies / simple musical instruments, etc for the evenings..they can all be powered with a light or two.

Set up a secure outdoor place to set up a cooler for food storage...use your climate, maybe winter is great big freezer...maybe you'll find a buried cooler will work well enough in summer? Maybe you'll need to buy more solar panels and a charge controller for a freezer, but maybe not?

Get some low-draw led lighting so you have lots of light available in the evening without drawing your system down too much.

The truck batteries will work if you've already got them. If you're buying batteries get real deep-cycles for better performance.

Hope that wasn't too sanctimonious. Just stuff I believe in...








 
Kathy Burns-Millyard
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Location: Arizona low desert
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Kari those are excellent points. When we started we had an led tent light, Portable media player, cell phone and netbook. The media and computer were occasional use only. We added on as we became more familiar with what our system could handle. We also pitched the inverter and went to 12 volt and usb chargers only. That helped a lot in the beginning.
 
Pamela Teele
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I did use the calculator. I had the right idea as far as battery count. Just way off on other things. Very big help. I'm going to look into the cooler ideas, just not so sure how I could do it to prevent black bears from getting in them. Gotta love wildlife This is an experiment all new to me. Thanks for the ideas. I'll keep check for new useful tips too.
 
Kathy Burns-Millyard
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Location: Arizona low desert
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Hi Pam,
I just finished and posted the article here:
http://www.sasez.com/solar-power-lessons/

Please let me know what I've missed or if I can help further.
Thanks,
Kathy
 
Chris Griffin
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Location: Eastern edge of the Blue Ridge Mnts. Virginia
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Pamela Teele wrote:grounding? running copper wire over a piece of plywood to 3ft piece rubar as a lighting post to protect the inverter. Will that be enough? I'm not sure the inverter will be enough. can you run 2? I have been looking to add an 1800 watt total home kit. But I'm not sure how much power that will give. Sales people around here have no clue when I ask questions. thank you.


You can't run two inverters to the same circuit, but you can run two when using 230 VAC distribution panels. I have not tried to run an appliance that uses 230 VAC, but it is easy to use single circuits (115 VAC). I don't see any reason to run two except for redundancy. If you have no access to the grid, I would keep 2 inverters on hand no matter what.

It is very difficult to find anyone that has a complete understanding of solar power because most electricians are so wrapped up in KWH and solar is not rated KWH. The best question to ask is "How fast will a particular solar kit recharge a standard car battery rated at say 600 cold cranking amps?" Not that you will get an answer, but maybe one or two of the sales people will take a moment to do some research. A 95 watt system can take up to a week to fully a charge a new commercial size tractor battery (I don't remember the amp rating, but I will check it and come back and edit this post to add it in). That can give you an idea on what to look for.
 
Andrew Kendall
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I have purchased a small solar system from a great place in AZ. Their web site has all sorts of great info, and also some formulas to help answer any questions that you might have. One very good tip that they gave me was to use golf cart batteries. they are made for the type of charge and discharge that you need with a small system. Their web site is http://www.solarpenny.com I have always talked to a guy named Aaron. They really know their business. Solar is all they do.

There is also a guy on youtube that has several informational videos. His name is Lamar Alexander. Here is a link to one of his first videos http://www.youtube.com/user/solarcabin

Good luck
 
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