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Old 12-23-2008, 11:32 PM   #1
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Re: Solar Input

I cant' really comment too much on your numbers and figuring as I haven't gotten that far. They do take into account things I do know, which is that a battery is rated under "perfect" conditions and therefore maximum AH's are often more theoretical than actual. And you're right, you don't want to drain past 50%.

I see you're a fan of AGM's!! I have one and think all new additions will also be AGM.

Now... why would you want to live all alone in a huge bus?

-Ray

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Old 12-24-2008, 06:34 AM   #2
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Re: Solar Input

smitty;
i just went thru the latest mother earth news energy aver edition, lots of good information, most notably updates on solar panel technology, not much on storage as most current home systems are connected to the grid as the power companies are required to buy back the extra power produced at the going rate.

i think that with the current push for hybred vehicles that new battery technology is on the horizon especcialy from the asians.

has anyone looked at industrial batteries like forklift batteries ?
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Old 12-24-2008, 09:46 AM   #3
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Re: Solar Input

Hi Smitty-

Nice work so far...I think you're on the right track. Two comments though:

1. Those 305 Ah batteries are 6 volts, so if you get two and wire them in series you get 305Ah at 12 volts. Four of them will get you 610Ah total capacity at 12 volts. Then factor in the 50% usage limit.

2. The ad for the charging system uses 5-6 peak sun hours for determining charging capacity of the included panels. I'm not sure why they use those numbers, because it varies by location and time-of-year. There are tables showing how many sun hours can be expected depending on location and type of array (tilted, tracking, etc.)
http://rredc.nrel.gov/solar/pubs/redbook/

The tables can be a handful to look at initially, but unless you are building a tracking system, just worry about the first table.

The rows show the number of sun hours for each tilting configuration. The first row is for 0* ...or flat/untilted. Read across to see how many daily sun hours you can expect on average for each month.

"Latitude-15" means the panel array is tilted at your latitude minus 15 degrees. For example if I am at 40 degrees N Latitude and tilt my panels to 25* (from flat), the numbers on that row (Latitiude-15) are what I can expect.

You can use those numbers directly in your calcs to see how many amp-hours (or watt hours) your panels will put back into your system, on average, each day.

Sorry if that was long-winded but it took me a few tries to figure out the tables and I wanted make it easier for others if possible.

HTH
Sean
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Old 12-24-2008, 01:03 PM   #4
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Re: Solar Input

What kind of 12v fridge will you use? You'll want one of the higher efficiency compressor models, and it will need to be vented to the outside to remove heat. Build it into a cabinet and use low draw 12v fans to circulate air out thru the bus wall. Or put a roof vent for a RV fridge in and let gravity do the vent work. Otherwise the heat is dumped into the bus, making the fridge (and your cooling fan)s work harder. You won't operate a 2 or 3 way RV fridge on 12v for long. I'd opt for a propane RV fridge. It should really free up a lot of electric reserve.

I lived at BurningMan for a month last year, with 334 watts of solar (flat mounted), 5 Walmart group 29 RV batteries and a LP RV fridge. We were able to use 1 to 3 laptops, make a couple 4 cup pots of drip coffee, use the microwave (sparingly), lights, music. There were a few eves when the voltage dropped lower than I'd like, but not real critical. 3 of the batteries were over 1 yr old, had wintered thru sub zero temps, and suffered some healthy discharges the year before, so they prob dragged the system down a bit. Also, I pre-cooled the fridge, and ran it off the solar/inverter for the few hour drivew to BM; Really dragged the batt voltage down, even with full midday sun.

The year before, we were at BM a bit less than a month; the 334 watts plus 3 24 watt panels and 3 Walmart batts could barely keep up with a 4 cu ft dorm fridge. Unvented, the outside of the fridge would get hot!! These little things have an insanely inefficient design. My putting it under a counter w/ no venting made it much worse. Love my propane fridge!! A week of clouds isn't going to hurt it, nor will parking in the shade.
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Old 12-24-2008, 02:06 PM   #5
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Re: Solar Input

Cool Smitty. I figured you knew about the sunshine vs. latitude stuff, I'm just never sure how much info & opinions to spew, so I just start blabbing. No offense intended amigo.
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Old 12-24-2008, 04:33 PM   #6
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Re: Solar Input

Quote:
Originally Posted by Smitty

Are 6V batteries genetically higher AH than 12V? I guess I really haven't paid attention, and was paying more to AH and physical size. I may have to relocate where I intend to stow the batteries to ensure room for more reserve capacity.

Thanks
Smitty
I assume you meant "generally", not "genetically" and yes 6v batteries are generally higher AH batteries than 12v because they tend to be built to similar external dimensions but a 6v has fewer cells so each cell can be larger, therefore contain more lead and electrolyte, therefore more AH per cell and since the cells are series and AH are not added the AH of the battery can be no larger than the AH that can be built into each cell
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Old 12-25-2008, 12:42 PM   #7
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Re: Solar Input

If you're going to stay with an electric fridge, one option is the freezer to fridge conversions. Basically a top open freezer, add an internal thermocouple and controller to make it cycle on-off to keep temps in a fridge zone. They can run well off a relatively small inverter. There's lots of info out on the web, (if you can sort thru all the folks that only want to make money).. If you get the right freezer, they're supposed to be VERY efficient as a fridge. I think you can get the temp probe and controller from a beer and wine making shop. I believe some freezers dissipate heat through the skin, so I'd run it first before insulating, building an enclosure etc. Biggest trouble for us Skoolies is the floor space it takes up, and area above to let the lid open. I came really close to doing this, but opted for conventional RV fridge.

http://www.builditsolar.com/Projects/Co ... fridge.pdf

and a discussion of above
http://www.wind-sun.com/ForumVB/showthread.php?t=9

You can spend the time to find more!!!
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Old 12-25-2008, 01:46 PM   #8
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Re: Solar Input

Quote:
Originally Posted by elkoskoolie
If you're going to stay with an electric fridge, one option is the freezer to fridge conversions. Basically a top open freezer, add an internal thermocouple and controller to make it cycle on-off to keep temps in a fridge zone. They can run well off a relatively small inverter.
Hey, this is a neat idea. I am months off from buying a fridge for my bus but I have spent some time looking at various options and have never considered this one. I always liked the top opening chest freezers because they don't let all the cold air out when you open them! This means you can open them longer and more frequently without losing as much cold air. It's gotta be more efficient.

One more thing to look at and consider!

-Ray
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Old 12-25-2008, 05:33 PM   #9
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Re: Solar Input

Quote:
Originally Posted by Smitty
Sean- No offense taken, hope you didn't think that. Appriciated your input. lol, I don't think one can offer too much info. What doesn't benefit one (and not saying it didn't me, it did) can benefit another.

Thanks
Smitty
It's all good. The internet is an excellent medium for exchanging info and ideas, but sometimes I like to check to make sure wires haven't crossed somewhere.

Cheers!
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Old 12-25-2008, 08:54 PM   #10
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Re: Solar Input

Quote:
Originally Posted by Smitty

That being said, I'm wondering if there is any advantage other than a few extra AH when comparing 2-6V to 1-12V? Connecting 2-6V would add alittle cost (wiring & connectors) initially, as would mounting twice as many batteries using 6V's.

Thanks
Smitty

The advantage with a pair of 6v's is generally they are more resistant to vibration and physical shock because the plates tend to be thicker than in 12v, but 12v will usually let you pack more AH into a given amount of space and usually will be lighter for a given pack rating
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Old 12-26-2008, 05:56 PM   #11
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Re: Solar Input

Hi-

Yes, I used Kee Klamp structural fittings along with 1.5" SCH40 galvanized steel pipe to construct the mast and support legs. The turbine is a 400-watt Air-X model from Southwest Windpower.


Main mast is 10', support legs are 7'.

Detail of support legs and mast connection:

McMaster part #4936T56


Detail of deck attachment:

McMaster part #4936T66

My only complaint is that the steel pipe is quite heavy and it's a little scary to set up while standing on the deck. I'd love to come up with a way to erect it with less danger factor. Another issue, albeit a small one, is that there is a bit of noise in the bus when the turbine spins. I haven't experimented with rubber mounts or the like but I imagine improvements could be made to the mounting system.

HTH
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Old 12-26-2008, 09:08 PM   #12
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Re: Solar Input

I'm not an expert- this is based on my research before I started putting my system together.

I'm pretty sure that most solar controllers won't handle a wind generator. The Air-X has an integrated controller and is "plug and play"; it is simply connected to the battery. It can be used while a solar controller is also connected; they both simply connect to the battery terminals. If the wind generator isn't self controlled, it will need a controller that upon full battery charge sends voltage to an external shunt, something like a space heater, bank of lights etc. OR has the ability to short the turbine to create internal electromagnetic resistance (what the Air-X does). If the controller simply breaks the charging circuit (somewhat like a solar controller does), the wind turbine can free-wheel, possibly over speeding and causing damage to itself or surroundings. Of course these functions can be accomplished simply with a set of switches, but then will need monitoring or be manually over-ridden/ turned off; i.e. it won't be a 24/7 automatic system. sw 1. = charge sw2 = external load sw3 = generator shunt.

Chuck, you're right on with the light plant mast. I've been looking for one for about a year now. Need to get that generator up above the turbulence. A quick crank-crank and you're up 20-30 ft. There's a dead one at a local mine I'm hoping to get cheap.
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Old 12-28-2008, 11:41 PM   #13
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Re: Solar Input

Smitty,
I think you're headed in the right direction with Sundanzer or Sunfrost food storage. That's what the off-grid folks around here use (where the winter sun rating is only about 4 hours per day). Steeper price up front, but super, super efficient. If I can get a bus going, I would prefer those with a couple of extra batteries over the typical RV AC/DC/propane units.

I would probably prefer the Sundanzer chest style over the Sunfrost, even though they take up more room, because I don't want all the cold falling out on the floor when I open the doors. But then again, everybody's style is different.
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Old 12-29-2008, 07:57 PM   #14
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Re: Solar Input

smitty;
iirc small cruising sailboats use chest type plate freezers that can be recharged with minimal electricity. I also recall someone on the truck conversion forum that claims he can keep his chest freezer frozen with only one hr of 120v per day, he opens the freezer once or twice dailY and uses it to fill a cooler that he uses for a day box. the boat people put hteir frozen oods on the plate and mthen load the freezer with refrigerated product on top or close to the door/lid.

with some outside of the box thinking an efficient plate type refrigeration system could be designed into a countertop/workmarea.
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Old 12-29-2008, 09:01 PM   #15
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Re: Solar Input

Quote:
iirc small cruising sailboats use chest type plate freezers that can be recharged with minimal electricity.
My sister and her husband spent a year June 2007 - June 2008 cruising with their kids, Maine to Bahamas and back. That jogged my memory. I remember he told me he custom-built (re-built?) a super-insulated enclosure for the boat's food-cooling mechanism. A custom-built box might help save $$$.

I would need to have refrigeration. Two of us go through an average of about a gallon of skim milk per day. That includes the quarts I bring to work every few days for my coffee.
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Old 12-29-2008, 09:09 PM   #16
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Re: Solar Input

Particularly if you're going solar, I'd say go with the propane fridge and free up the power draw of the fridge. They work great and use so little propane that a full bottle will last you eleventy zillion years. Almost.
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Old 12-30-2008, 08:17 PM   #17
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Re: Solar Input

Quote:
Originally Posted by Smitty
I plan to change alot in the way I eat, as opposed to the way it is now....lol, get hungry, go to fridge & slap something in the frying pan. I plan to eat alot more fresh (caught) fish, as well as more wild game (small game that won't require being stored, other than maybe 1 meal worth of leftovers).
Start making those changes now!!

Quote:
The more time passes, the more I want to talk myself completely out of even using solar & refrigeration. I'm not a huge milk drinker, but it can be purchased in powder form, butter can be canned, eggs (from what I understand) will keep a fair amount of time without refrigeration, meats can be canned, as well as cheeses. I doubt it will come down to that though, however I may give serious reconsideration to the extent of solar funding I'm willing to spend.
I have mostly given up any plans for serious solar. My reason is that I HATE HEAT!!!! I hate the sun! I burn to a crisp, I want it cool, I will find the coolest, shadiest place to park so I can enjoy being there. If I were to park in the sun on purpose I'd use more in AC to make it cool than the solar would put out!

You're right about the various foods you can get in canned form. I eat a lot of food from these guys:

http://honeyvillegrain.com/

Their powdered milk is quite passable. Their powdered eggs are also okay, tasting just fine but have a slight "off" texture... mixing in one real egg goes a long way to fixing that. My typical breakfast consists of a bowl of cereal (out of a can), milk (powdered, out of a can), a handful of blueberries or strawberries (freeze dried, out of a can) and a spoonful of sugar to make it a bit sweeter. Except for the sugar it's all out of cans! The milk I make up the evening before and chill it in the fridge overnight. I also eat a lot of freeze-dried veggies (out of a can) that are much tastier than wet-canned veggies, almost as good as frozen veggies, but require no refrigeration. They sit in a dry can. You put a handful in some water to hydrate a while and they're ready to cook.

With some changes in lifestyle and eating habits you can really cut down your need for refrigeration. In my home over the past year I quit using a full sized freezer and got rid of my huge fridge/freezer and bought a smaller refrigerator. There are three of us in the home and I often find my fridge is more than half empty. I should have bought an even smaller one!
In my bus I plan on using the smallest, most efficient refrigerator that I can find or make. A fellow has to have SOME refrigeration, at least for beer.

-Ray
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Old 12-31-2008, 12:01 AM   #18
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Re: Solar Input

Hey Ray, drink box wine & ditch the reefer
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Old 12-31-2008, 12:09 AM   #19
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Re: Solar Input

Quote:
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Hey Ray, drink box wine & ditch the reefer
Hehe.... I do drink boxed wine!

-Ray
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