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Julie2Oregon
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# Posted: 4 Oct 2014 05:45am
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I know this unit is pricey BUT it's my big splurge because of my need for convenient, efficient, reliable refrigeration. Is anyone using or know anything about the EcoSolarCool Solar 6.2 cu. ft. Fridge/Freezer? It only uses 85 watts and has good reviews at Amazon.
http://www.amazon.com/EcoSolarCool-Solar-Refrigerator-6-2-Cu/dp/B007VKX1FS/ref=cm_cd_ al_qh_dp_t
I'm doing off-the-grid solar -- would you do a dedicated panel and 24V battery for this fridge (it does need 24V)? I'm thinking so, as opposed to adding it to my array/bank which won't be comprised of 24V batteries! But I don't know.
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MtnDon
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# Posted: 6 Oct 2014 01:31pm
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Don't know anything about that unit. It appears to use a Danfoss type compressor. Those are good. More research needed to verify that.
Have you built the PV system yet?
I'd build it to 24 volts and try to use a single string of batteries to make the 24 volt battery bank.
You could use an upconverter to change 12 VDC to 24 VDC as the fridge mfg states. But depending on your power needs a 24 volt battery bank may be advantageous. If there are 12 VDC devices you need to operate you can use a down converter, 24 to 12 VDC for those.
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MtnDon
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# Posted: 6 Oct 2014 01:33pm
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IMO, planning on using both 12 volt and 24 volt systems is wasteful and more expense and maintenance.
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Julie2Oregon
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# Posted: 6 Oct 2014 05:39pm
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Hi MtnDon,
Thanks for the reply! I'm trying to educate myself on solar and figure out a budget and plan for the cabin. I will hire it done but I want to be able to discuss the system and options knowledgeably with the solar contractor!
I did the load calculators and it seems a 1,600 kw system will do the job. I'm looking at a 600-watt turbine, too, to help with battery charging on gray winter days. And, of course, I'll have an inverter generator.
My system will power this fridge, one flat panel TV, a small DVD player, a CD player, three lights, a 1,300 watt hot plate and an 1,100 watt convection microwave. I'm doing convection because it's steadier and faster. I won't be using those more than 15-20 minutes each day. The DVD and CD players will only get occasional use. I have a battery-powered radio.
The battery thing is so confusing. I've seen different recommendations everywhere, from 6 volts to 24 volts. The amps vary so greatly! That's why I was thinking of just putting the fridge on its own, dedicated panel and battery so I didn't have to worry about that appliance. The rest is rather negotiable. I could always cook on my woodstove, use more oil lamps, and read. ;) Building codes state I need to have a light in the bathroom and such; otherwise, I'd just use an oil lamp there, too!
Any advice you could offer would be most appreciated!
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MtnDon
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# Posted: 6 Oct 2014 06:43pm - Edited by: MtnDon
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Quoting: Julie2Oregon The battery thing is so confusing.
One thing to keep in mind is that several batteries in series, in one series string, is superior to having any batteries in parallel. Avoid parallel battery connections if you can. Sometimes the budget is part of the problem as most other batteries cost more than the golf cart GC2's many of us like to use.
So the idea is that once the total watt-hours capacity is known, or the amp-hour capacity at a certain voltage is known, then the battery shopping can begin. I like to calculate in watt-hours as then the voltage is irrelevant.
Volts x Amps = Watts
Volts x Amp-hours = Watt-hours
If you know the watt-hours total to be, say, 2500 watt hours, dividing the 2500 watt-hours by 24 volts = 104 amp-hours (@ 24 volts).. Knowing we should not discharge more than 50% we would multiply 104 x 2 = 208 amp-hours battery capacity needed. (@ 24 volts). In this example four series connected 6 volt, 225 amp-hour golf cart batteries would be just about ideal.
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Quoting: Julie2Oregon a 1,300 watt hot plate
That will suck a lot of your power up if it needs to operate on high to bring several quarts of water to boil for example, and then keep it going long enough to boil potatoes. Even worse if you have high elevation. Off grid cooking is most often propane. Or wood stove if you are up to that.
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Quoting: Julie2Oregon an 1,100 watt convection microwave
The microwave too will use a lot of power if used for periods of time longer than just a few minutes to warm a lunch.
Just to be sure you accounted for it in your math, you are aware that a microwave rated at 1100 watts means 1100 watts cooking power and that the m-wave will be drawing something like 1600 - 1700 watts while doing so.
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MtnDon
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# Posted: 7 Oct 2014 12:57am
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Of course an alternative would be to throw in more PV and maybe more battery and buy a 120 VAC energy efficient refrigerator. Many folks who are off grid have taken that approach in the last couple years as PV $$ have dropped and refrigerator efficiency has risen.
Does anyone know when the next step up of the EPA efficiency mandates are scheduled?
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Julie2Oregon
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# Posted: 7 Oct 2014 02:40am
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MtnDon,
Thank you so much for all of this helpful info! I had no idea the cooking appliances would draw that much power. The load calculators just asked me wattage and how many minutes/hours daily they would be used.
Geez, some of the solar sites recommended three parallel strings of batteries and others said that was inefficient. Which type of battery is best?
I thought my only choices were big gas appliances, camping gear, or smaller standard electrics. But I saw that nifty propane three-burner cooktop using a grill type of propane tank in another member's cabin build and that would be ideal! I will still get a countertop convection oven but considering that I'll only use it a few times per month, it would make sense to plug it into the generator.
This fridge/freezer seems to be a quality unit from what I've read. I'm going to stick with it. It can be run a few different ways and is well-insulated. Plus, it's a good size for my space. I like the freezer on bottom with the compartments.
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MtnDon
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# Posted: 7 Oct 2014 09:37am - Edited by: MtnDon
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Quoting: Julie2Oregon Geez, some of the solar sites recommended three parallel strings of batteries and others said that was inefficient. Which type of battery is best?
Northern AZ Wind Sun is a great vendor and operates a forum independent of their store. There are some very intelligent and experienced moderators and general members. Some work in the PV industry repairing failing systems built by others. Have a look over there and see what their thoughts on batteries are. You will find single series connected strings are best.
I agree that refrigerator looks nice. We have a propane fridge since about 2007. Just as expensive as the one you linked to, but a little larger. If I was starting afresh today I am not sure which way I'd go. If it was for full time living I might go with a regular Energy Star 120 VAC and put up more PV. But if it was part time I'd either go propane or maybe one of the efficient 24 VDC fridges. Not sure. ???
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creeky
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# Posted: 7 Oct 2014 02:56pm
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Julie I'm one of those people who has sold their propane fridge and gone to a standard electric fridge.
And, based on 4 years off grid, I recommend forgetting 12v/24v appliances. Spend the money you save on appliances and get a good inverter. 120v regular ac appliances are mass manufactured. The savings are considerable.
I run my fridge on a 1.5 kw solar system that also runs a 700 watt microwave, tv, stereo, 2 water pumps, lights, computer ... etc. etc. etc.
Comparing to your ideal fridge: I paid 400 for a standard 10 cu ft fridge. That would be an 800 dollar savings for you. It consumes 500 watts daily winter and 1 kw daily hot summer day. I see magicchef has a bottom mount freezer at $450 and it's 9.2 cu ft. That would be perfect for you. More space too. And $750 was just added to your solar budget.
The new energy use standards are now in effect I believe. My 10 cuft was rated at 315/kw annually. The new ratings are much more conservative. But in actual operation I'm using more like 250-275 kws/yr. They test at 75 (25C), which is much warmer than my house usually is.
Compared to propane: My fridge is now "free" on propane savings plus over 200 dollars ... add the "green" benefit in 0 carbon emissions.
Glad to hear you're looking at a propane cooktop. I use 20 lbs of cooking propane roughly every two months. I cook a lot as I enjoy it. So my propane use is probably fairly high. I did use an electric kettle to boil water (I have a big battery bank) but when a friend admired it (it was glass so you could see through it) I gave it to her. I miss my kettle. Tho the new one has a pretty handle. smile.
Btw. I used to be a fan of the wind and sun forum. just watch out for "angels dancing on the head of a pin" types. Perfect is the enemy of good, as the old saying goes.
They have a beginners section.
Note that while MtnDon recommends a series string, both he and I run 3 paralleled strings. Mine has been working flawlessly for 4 years. I think his is now on year 5.
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MtnDon
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# Posted: 7 Oct 2014 04:27pm
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Quoting: creeky I think his is now on year 5.
True. And also true is I have 2 cells that don't come up like they should anymore. I may ditch one of the strings come spring. I think there has been a certain amount of luck involved as I know two others with triple parallels who have not made it to 4 years. One replaced all the batteries at three years and changed to a 24 VDC system while they were at it.
One thing that can help prolong the life of parallel strings apparently is to keep the discharges to maybe 20 - 25% maximum. From what I have learned in the last 5 years deep cycling multi parallel strings can exacerbate the uneven discharge and recharge thing that causes trouble.
As for the NAWS forum, they have the same approach to PV and wind power systems as I now have towards the use of pier and beam foundations in building habitable buildings. It is true I also have a cabin on piers and beams. It is also true I have learned more about the engineering and the pitfalls of piers just as I have seen problems with parallel strings. Not all pier foundations develop problems or at least, not very quickly. Same can be said for parallel batteries.
I keep mentioning the pitfalls about pier foundations when the subject comes up, just as the NAWS guys will "harp" on the problems many beginners make for themselves when building their first PV system.
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creeky
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# Posted: 8 Oct 2014 04:27pm
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that's the great thing about doing. you learn as you go along.
your batteries being in parallel strings, one disadvantage to series strings is their vulnerability to the "one bad cell" problem. As it was explained to me. and lots of folks with series strings have toasted their battery sets in months or a few years. look at some of the RV stories. over discharge/high heat doesn't care how many cells you have how. no?
If you hadn't built post and pier. would you have built at all? or would the much higher foundation cost changed your plans?
so Julie. rethink your expensive fridge. back on track. whew.
seriously. you want lights a tv etc you're inverting power. why have 120v ac plus 12v dc plus 24v dc. too complicated.
and the 750 you saved on the fridge goes a long way to buying a really good inverter/charger/ats. I'd spend my money there. and wire for just 120v.
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MtnDon
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# Posted: 9 Oct 2014 02:48pm - Edited by: MtnDon
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I would have built a PWF, or possibly a block foundation with SBC, but would have built. I had received what would be best described as incomplete advice and went with as it was cheaper. Initially cheaper. Now I realize the many advantages either of the options would have offered. Live and learn.
As for series problems I have seen many fewer with serial connections than parallel. And that has been confirmed by engineers I have talked to in recent t years... post assembling our PV system.
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creeky
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# Posted: 9 Oct 2014 05:44pm
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there are always new discoveries being made. good thing 
Oh. So Julie. take your 750 saved on the fridge and look into LifeP04, LFP or also known as lithium iron phosphate batteries. they make lead acid look like a 70s ford pinto compared to a 2015 ford fusion. no comparison. so serial or parallel. what do you care? you're buying a battery pack that is modern, requires no maintenance and is smaller, safer and easier to install.
A friend of mine who is a retired physicist looked at my discovery of Balqon battery systems and gave it the two thumbs up. His son, 25 years of engineering/installing large solar battery systems is currently (ha ha) engineering a 60kw lfp system, also approved. So LFP is now the real if emerging solar storage media.
You are very lucky to be buying just when this new tech is becoming affordable.
MtnDon. that block foundation would also be compatible with the "perfect wall" which uses a block wall. you'd have a "500 year house." healthy and with very low energy use.
sadly, on my soil, a block foundation would sink out of site in 10 years, but that's another story. tho I have some ideas on a modified/floating sbc/rubble foundation I found on another site. I'm thinking to build an experimental model next year.
serial vs parallel: let's be honest. there is no way either of us would buy another lead acid battery pack if our packs died tomorrow. so serial over parallel only matters with small weekend use diy solar systems now.
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groingo
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# Posted: 9 Oct 2014 07:03pm
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CREEKY:
Balqon does look interesting and they appear to make the battery that would work in my application, if only they would answer their phone?
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MtnDon
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# Posted: 9 Oct 2014 08:23pm
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Re, what would I do if the present bank of golf cart GC2's needed replacing today?
$1200 worth of Trojan L-16 RE (4 in series) . I know with a high degree of certainty what to expect from them. When it can be widely shown that LifePO4 do as well as FLA in RE, off grid, use I would reconsider. They do well in EV usebut the discharge / recharge pattern is different in RE use. That gives me cause for delay.
That's me... generally slow to adopt "anything" until it has a track record I can live with. No first year new car models for me. It's why I skipped Windows Vista and why I just ordered a new laptop with Window 7. Etc.
How many solar newbies have trashed a new set of batteries? Nobody can say LifePO4 is bullrtproof. People do stupid things and while some of the old stupid things won't kill a LifePO4, there are some that will. I need to see that the BMS is foolproof, for example.
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Julie2Oregon
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# Posted: 9 Oct 2014 10:52pm
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OMG, so now I sort of get the solar thing and now I find out that a post foundation isn't good?
Creeky, I'm impressed that you power everything with a 1.5 kW system. Yay! At least that may be one thing I figured right. What do you do for baking? (I love to cook, too.) I figure I'll run the convection oven off the generator when I need to bake something but is there a better way?
But back to the foundation -- I don't want poured concrete and I do have to meet Earthquake standards because I am going to be living on the West Coast and that's just part of the deal and requirements.
I figured the post foundation with tie-downs would be great because it would provide good support for the cabin (This isn't an area that gets a lot of rain. It's high desert and I will be on a mountain.) but wouldn't be so rigid that in the event of tremors my walls and such wouldn't crack from no give. Am I being stupid?
I'm looking at the regular fridges, small size. The Magic Chef has lousy reviews. Does anyone know anything about Danby?
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MtnDon
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# Posted: 9 Oct 2014 11:44pm
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An earthquake will shake a pier foundation apart. The piers won"t necessarily move in unison. They are independent of each other. Check with the bldg dept where you plan to build. Also, is there a high wildfire danger? Many areas in CA have special constructions requirements if wildfire danger is high.
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MtnDon
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# Posted: 9 Oct 2014 11:47pm
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I can't comment on the Danby, but if you want to compare energy efficiency Google energy star appliance ratings. There's a website with info, brand by brand.
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Julie2Oregon
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# Posted: 10 Oct 2014 03:51am
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Yes, I've tailored my search results to Energy Star-rated fridges and the Danby model is. The selection in that size is very limited, of course, and it looks like the Danby is the best bet.
I did speak with the county planning/building folks and there aren't wildfire requirements. (I'll be in Oregon.) Earthquake and snow load are the two special considerations, along with the others.
What sort of foundation would you recommend, MtnDon? I will be living on a mountain but much of my parcel is level, except in the back where it borders BLM forest. My building area is level and clear, thanks to the previous owner. We're not talking California-style earthquake regs.
I was hoping to have a crawl space under which to put my pillow water tanks and I was going to add a "dog house" to the outside, with a little access door on the inside, for my deep cell batteries and other utility items.
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LastOutlaw
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# Posted: 10 Oct 2014 01:16pm
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I'm getting ready to try out a modified chest freezer at my cabin. The Killawatt showed it consumed around 300 watts in a 24 hour period and that was empty.
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creeky
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# Posted: 10 Oct 2014 02:35pm
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Hey last. looking forward to how your modified chest freezer works. 300 watts. that is sweet.
Julie. The magic chefs don't get great reviews. but as I noted. my is running fine and saving me money as I speak. Of course, I had a propane fridge previous. the Danby's are also excellent.
I would ask around locally about foundations. Local farm stores are usually a good honest place to start. We're not in your part of the world. so we don't have the appropriate experience. my .02.
On the solar side. I started with a 1kw system and 1200 amp hrs battery at 12v. That was more than adequate. But then I started adding a fridge. And a dishwasher. And a laundry washer. And ... so my battery pack is fine, but I needed more power for the high drain (dishwasher basically). And more is more.
My initial assessment, based on filling out the forms for my old house was that I needed a 4 kw system. Sometimes those "calculators" are full of something ...
Is this a recreational camp/cabin you're building or do you plan to live there full time?
Seriously. Do not buy deep cell batteries. Get a lfp battery set. The yacht people have been using them for almost a decade. They have the money to be the loss leaders. The RV folks have been using them for 3 years or more. Us off grid types are new to them, but they are being adopted around the world. Google the tech and go look at all the aussie and german companies building lfp systems. They are being installed in the tens of thousand. This is the new tech.
You do not want the maintenance headaches with lead acid. Trust me.
sadly my 720 lbs of lead continues to perform admirably. But if you get a lfp battery pack I will be very envious. Don't you want to be envied by me? (kidding)
Groingo. I sent Balqon an email asking about temperature derating on their battery pack, "silence." I did discover on an aussi site that lfp derates 7% at -20F. Compared to what 50% for lead acid?
Still Balqon uses Winston lfp cells and they have a top tier quality level.
I've heard prices are set to continue to fall. Fingers crossed. But it already has to many advantages to be overlooked.
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creeky
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# Posted: 10 Oct 2014 04:31pm
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er, two more things.
Julie. I use a full size stove. I was all set to buy a 24" danby propane stove (had an 18" propane) when I saw a "tiny house on wheels" build where the cook of the house said she wanted a full stove. I thought to myself. I love cooking. So I got a full stove. I bought it off kijiji (canadian for craigslist). it was 300 bucks. it has five burners. i love the center grill. I'm not much of a baker tho. so the oven still is unused. blush.
mtndon. ah yes. if you use very little power and only on an intermittent basis. 4 re l-16s in series = what, 325 amp hrs at 24v. that's a 1.5kw daily use for max lifespan (4000 cycles). LFP at today's price point might be a bit much.
Tho there's a 2.6kw pack from Balqon that costs 1430. It includes rack, cable, fuse, shipping. That's about 1.8 kw daily discharge at 70% (5000 cycles) dod. Plus, of course, 15-20% more efficient recharge. That's beaut any way you look at it.
Still, I could see how saving 210 dollars with l-16s and their higher maintenance plus shorter life span while weighing 3x more, and needing their own vented/air conditioned space etc would make sense.
Wait. No I can't. LFP rules. It's like when MPPT came out. Some people with really small systems still use PWM solar controllers. But if you're playing for real?
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MtnDon
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# Posted: 10 Oct 2014 06:08pm - Edited by: MtnDon
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Julie, if you want to get into the nuts n bolts of best practices for building a structure with a long life, look up the IRC. International Residential Code. Ask the local officials if there is an online Oregon version. I think there may be butI'm on a ridge top in south NM right now with a tenuous data coonection. We're getting rained on withe nothing else to do😕 right now. You need to know the local frost depth and while you are asking also the local snow load.
Note, their is not a step by step how-to manual. It does include the rules and 'prescription' solutions that are proven to result in safe stuctures. Piers are notable by their absence.
If member Don_P reads this he can direct you to resources for the IRC, and a snow load online service for OR. The IRC also has snow loads,, but in many places in the west it varies a lot depending on what side of what ridge you are on...
Best foundation is likely a full perimeter poured concrete or masonry block wall with reinforcement. Either would sit on a full perimeter concrete,,steel reinforced, footing at a depth that suits the winter climate. That would meet code and be suitable for virtually anyplace in the USA.
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MtnDon
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# Posted: 10 Oct 2014 06:16pm - Edited by: MtnDon
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Creeky, you either did not read or understand my hesitation to jump on the LifePO4 bandwagon. When LifePO4 gets more widely adopted in the RE field I could consider them. Not before. I really don"t care how much FLA weogh. They only have to be transported once.
I'm not going to say anything more about LifePO4 in thread unless specifically asked. We are different, have different approaches to things.
..and, yes, MPPT is good proven technology. But there can still be a place for PWM as you mentioned.
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MtnDon
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# Posted: 10 Oct 2014 07:49pm
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Julie, you might want to start a new thread on foundation questions. That should catch Don_P's eye.
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creeky
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# Posted: 11 Oct 2014 03:22pm - Edited by: creeky
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MtnDon. I understand your hesitation about lfp. but it's not a bandwagon, it's a current real life solar installation tech.
and thank goodness. lead acid is a pain to maintain. has absolutely terrible performance in hot/cold climates. relatively short lifespan. and is not environmentally sound.
There is a kick back from entrenched suppliers, true.
But, would we not be remiss, as small cabin enjoyers, if we didn't support and explain better ways of doing the things in this wonderful off grid/small cabin forum?
Julie. MtnDon is a lead acid aficionado. We really don't know how much power you're using/plan to use/etc. For very small installations lead acid is still a viable option. And "now," for anyone planning an installation where occupation occurs for more than a weekend or ... you would be remiss not to look at lfp.
I'm not on a bandwagon, but nor am I a leaddite.
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Julie2Oregon
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# Posted: 13 Oct 2014 04:48pm
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I'll be living there 24/7. On my system will be a fridge, a few lights (but I'll be using oil lamps quite a bit just because I like them. ), one 39-inch flat panel TV a few hours per day, one small water pump, and occasional use of a small CD and DVD player, 1100 watt convection oven, and some laptop charging. (But I do have a separate solar charging system for my cellphone and laptop so it would be an infrequent thing.)
My incinerating toilet system is passive solar and will use no power or water. I'll be doing cistern water at first via pillow tanks in the crawl space of the house so the water won't be pumped far. Hence, no need for a large water pump. I'll be using an on-demand gas water heater.
I'm considering a 600-watt turbine to help with battery charging but haven't decided for sure yet.
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