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Small Cabin Forum / Off-Grid Living / What kind of solar setup do I need?
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The Famous Grouse
Member
# Posted: 13 Feb 2017 11:30pm
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I'd like to get opinions on what kind of a solar setup I need.

Here's my cabin situation. I have a hunting property that is 120 acres and I'm landlocked in the middle of a section. It would cost over 10k to run power, so I'm staying off grid.

The cabin is for weekend use so we arrive Friday and leave Sunday. Most use is in spring/summer/fall with only occasional winter visits.

I have a generator so solar is not the only means of power, but my idea is to run the generator only when heavier power needs would drain down the system too much. So my plan would be to arrive and use the generator to cool down the fridge, run the well pump to fill the holding tank, etc. Then shut down the generator and run off of solar as much as possible.

I do want to run an inverter so that I can just plug in normal AC devices.

Basically, my power needs are:

- Undercounter refrigerator. As few watts of draw as I can find, but one of the 34 inch tall under counter fridges.

- Misc lighting, all LED bulbs. Probably an average of 3-4 LED lights on at at a tme on average at night. Say 30 watts total draw.

- 12 volt demand water pump. I have a well pump as well, but that only runs when the generator is on to fill the "holding tank". From there I can run the 12 volt pump to supply water to the cabin because that is more efficient.

- Misc occasional use items. Fan, radio, small LED TV.

- No power hog appliances other than fridge. No microwave, no air con, etc.

It doesn't bother me to run a small deficit in charging vs use as long as I have enough for a weekend.

What's the solar system for me? Panel wattage, # of batteries, inverter wattage, controler, etc.

Many thanks.

Grouse

Steve_S
Member
# Posted: 14 Feb 2017 07:17am
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Well, you rounded out what your plan is fairly well but having a better (accurate) number on Amps / Watts being pulled by your equipment is important. While a little fridge may not pull huge while running, a compressor start up does pull a lot for a few and an inverter needs to handle that plus, so it does not trip breakers or overheat.

A key part is type of inverter... Pure Sine is best for all electronics and modern motors but this is also more expensive than Mod or Square wave sine inverter's which can damage sensitive electronics.

Another point to consider as this is not a Full Time place, security ? Leaving a solar system unattended and in a remote area can lead to loss and subsequently a great deal of Sailor Talk. There are systems which are portable (you can take it down and store indoors or take it with you). Of course this "convenience / peace of mind" comes at an extra cost which can be a tad daunting.

On fridges (I assume you have not bought one yet) certainly look at the small "bar" type ones but also have a gander at what is often referred to as Apartment Fridges. They tend to be a bit larger but also more efficient than smaller ones per cubit foot and can often be found on sale at good prices... I got mine at Costco at an amazing price due to a model change (Danby changed the trim for the model yr).

For portable Solar Generators there are complete products like the Goal Zero solutions: http://www.goalzero.com/heavy-duty which are a bit more $ but easy plug & play.

Some general Solar Generators, Kits and other that makes it a little easier to compare: http://www.earthtechproducts.com/solar-generators---solar-backup-generators.html

As you can see, prices are wild and that "Market Bears Pricing" makes it even more important to shop around and get the best bang for buck because there is always someone out there ready to empty your wallet.

Other options may be to look at "RV Solar Kits" and Small Cabin off-grid kits which will give you different price points. There is nothing wrong with using an RV or Marine kit on your cabin, very little difference BUT their kits are more "mature" in many respects and designed for a tougher life.

Hope it helps

groingo
Member
# Posted: 14 Feb 2017 11:41am - Edited by: groingo
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From your description and power needs and to keep it simple your best bet would be to get a Honda 2000 generator which would give you the power you need when you need it and just sips gas when you don't....that would handle all of your power needs for your short stays.
Unless you go a properly sized solar system you will always be facing power shortfalls and having to run the geny to keep up....it's kind of the all or nothing predicament.

Your most cost effective solution is a good fuel sipping generator that can do what you need quietly and for a long time and requires little fuel to do it.

The Famous Grouse
Member
# Posted: 14 Feb 2017 12:46pm
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Appreciate the replies.

I do have a generator, but because this is a hunting property, I don't want to have to run a generator 100% of the time. I do, however, plan to include a battery charger in my system so whenever the generator is running, it will be charging the batteries as well. Ideally, I'd like to only have to run the gen for a hour or 2 per day unless heavy power tool use or other things require it. Because my needs include a fridge, I view a generator-only solution as a sub-par solution because it would have to run 24/7.

I agree, I will shop for the largest fridge at the lowest wattage consumption available when I’m ready to buy.

From the research I’ve done, it seems like the Energy Star certified under-counter fridges of 4-5 cubic feet are about what I need and have what I consider an “affordable” energy consumption.

For the sake of this comparison, let’s say I’m using this fridge:
http://www.bestbuy.com/site/insignia-4-3-cu-ft-compact-refrigerator-stainless-steel-l ook/5047300.p?skuId=5047300
If one can believe the online specs, this one uses 180 watts of power while running. I’m calculating this myself using amps x volts based on the specs given on this website.

Calculating watt hours needed is VERY slippery to me because there’s no way I can see to get accurate figures on how often a device like a fridge runs in the course of a day. If I use the Energy Star estimate from the above fridge:

294 KWH per year / 365 days = 805 watts per day? Did I do this correctly?

I agree, a pure sine wave inverter would be the most desirable and that’s part of the reason for this little exercise. Based on what other’s experience indicates that I need, I’d like to see the cost of the required PSW inverter. I may elect to limp by on a MSW inverter if the cost of the PSW is too much because of the required size. If that limits the delicate electronics I can run, so be it.

I have the advantage that I’m only 90 minutes from my cabin, so with most systems like this solar system, I pre-build and test everything possible at home before taking it up to the cabin. I plan to pre-build and test this solar system in my yard and with most relevant appliances like the fridge before I take it up to install it, so hopefully I can work out any bugs and if some appliance or component doesn’t work, I’ll return it and get one that does.

Security is of minimal concern. My property is landlocked with access through a hidden driveway on a neighboring property. At the closest, I’m ½ of a mile from any road and the cabin is not visible from any road. I have trail cams up for security and I have never captured a trespassing perp on my cams in 3 years of ownership.

Besides the cabin, I also have a shed with a roof slope that faces south, so this would be an ideal place to mount solar panels. I want a system that stays set up and charging all the time, not a “portable” system that gets folded up because then my batteries would not be charging between visits.
I have my own estimate for components needed, but I wanted to see how that matches other’s ideas without influencing people with my answer.

Any estimates greatly appreciated for:
- Panel wattage needed
- # of batteries needed
- Inverter size needed

Grouse

spoofer
Member
# Posted: 14 Feb 2017 05:52pm
Reply 


I would buy a 200 watt system from Renogy. I would add 2 six volt golf cart batteries to the mix. For about $600 this should be good enough to get your feet wet in solar.
I have a 100 watt system an my weekend hunting camp, and 90% of the time it is adequate. I run 4 twelve volt led lights, radio and small 19 inch TV. I don't have a fridge or a 12 volt pump. I do have a 2000 watt Honda penny when I need more power. It seems to rain or snow in northern NY 8 days a week.

The Famous Grouse
Member
# Posted: 15 Feb 2017 04:45pm
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Would 200 watts of charging power and a pair of 6 volts be enough for my needs?

I'm not sure I'm calculating this out right, but the fridge I put a link up to seems to show 805 watt hours per day of use. Again, if I'm figuring this out correctly.

So 200 watts would replenish that drain in 4 hours only under ideal conditions. Realistically, it would probably take 6-8 hours. on an average day.

I'll throw out what I was thinking.

I was thinking of:

4x100 watt panels.
2 x 120 amp 12 volt batteries wired in parallel
2000 watt constant use (3000 surge watt) inverter.

And I'm even questioning if 400 watts is enough charging power?

Am I way off the deep end/overkilling this?

Many thanks.

Grouse

frankpaige
Member
# Posted: 15 Feb 2017 05:12pm
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Hope you get an answer. Lurking about with about the same requirements. It's a puzzling area for me.

The Famous Grouse
Member
# Posted: 15 Feb 2017 05:58pm - Edited by: The Famous Grouse
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I'm with you, Frank.

With the advent of LED lighting, the lighting part of the equation is pretty minimal and it's pretty easy to estimate.

In my case, using a 12 volt demand water pump is also pretty easy to estimate and the pump's draw does not have a big impact on system size. I figure the pump runs 30 minutes a day max.

The two things that REALLY are difficult are:

- The inverter. How much power does a PSW inverter consume at "idle"? Very difficult to get any kind of answer on this, but obviously it's a consideration because I'm going to have a fridge so the inverter has to stay on all the time.

- The fridge. Yes, you can get the amp spec, but that's only when it's RUNNING. How often does a fridge run during the course of a 24 hour day? Again, very difficult to find any info on this.

I'd at least like to know if I'm in the ballpark. I hate to spend all the time and money rigging up the system per above and then find out I was missing the mark by 50% or more.

The only direct experience I have is helping rig a friend's cabin at his camp in the Canadian arctic. But he only uses a small inverter for occasional use and it gets turned off when not in use. No fridge, and his lights are DC as is his water pump. He gets by on 100 watts of charging and a single 12 volt battery, no problem. But that's a much simpler system.

The Wildcards to me are the fridge and the power consumption of the inverter itself. I have no idea if I'm close or off by a mile.

Grouse

Steve_S
Member
# Posted: 15 Feb 2017 06:24pm
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I would suggest something along the lines of this below. Now this is a Canadian Dealer so ignore the prices ! http://www.solacity.com/product/2-panel-cottage-kit/
Look for a similar kit from a more local supplier. It's fine to say X Panels, X Batteries & such but it's all the other stuff that will get ya.... Budget of course is up to you and what you want to afford.

100w/12v panels might seem cheaper but they aren't per watt, plus you want something that can expand with you if need be.

Batteries are a bugaboo, especially now as the battery tech is a fast moving beast that's gaining speed. Some are better than others, some cheaper, some more... It's enough to make one want to scream ! Marine/RV batteries... just don't. If you look at some solar supplier's you'll see how extremely radical the batteries can get.... Apply the rule of K.I.S.S. ! Stick with tried, true & tested which is reasonably priced...

creeky
Member
# Posted: 15 Feb 2017 11:22pm
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First. I wouldn't get 100w panels off egad or other.

Get big panels. Lower cost per watt. If you buy two big 300s at .70 it's 600 watts for 420. If you pay $1/w that same 400 gets you less power. And worse, a crappier quality. The big panels are better built. Better glass.

For your loads I'd look at 500 watts of solar.

An mppt controller. Of course. Big panels mean higher voltage. So to turn the high voltage into battery charging amps means mppt. I would probably also go 24v. And skip the 12v devices.

I've seen those smaller fridges down to 200. Your fridge will use less power than the spec. The test is in 75 degree heat with the door opening and closing with the regularity of a family of 4. So. Not opening and closing at all during the week. My 10 cuft (rated at 311) measures at 500w/day.

Get a pure sine inverter. Get a small one. The new high frequency inverters use 10w/hr. Compare that to the older models that use up to 50. But even 10/w (like my Victron at 8) use 240 watts a day. Add on 500w for the fridge. Lights. Radio. Tv. Pump. Your daily is probably around 1kw.

Btw. Folks typically oversize inverters. I use a 1200w Victron and it runs dishwasher, fridge, ac etc etc etc. I use up to 8kw per day. The advantage of a lower power inverter is lower idle losses. Note 2: this is a Victron inverter. So top quality. And price.

When you're looking at idle. watch out for "search" mode. Some inverters will operate in search mode. They'll only turn on when a load request is made. This might work for you during the week. But don't count search mode draw as idle draw.

For batteries. I'm going to disagree with Steve. Tried tested and ye olde solar. Old news. If you want a short term solution 6 volt lead acid golf cart batteries or solar storage batteries work. But if you want a cost effective solution. There are more and more lithium packs available. LG Chem. etc. Lifepo4 off of ebay.

Have fun. Solar is easier than folks say. Good luck.

groingo
Member
# Posted: 16 Feb 2017 11:00am
Reply 


One rule of thumb experience has taught me regarding estimating power needs....what ever you think you need Double it.....better to have too much than not enough.

The other thing I saw no info on was you daytime exposure....full sun is good but bright clouds are better for solar.

Good luck and keep updating.

Borrego
Member
# Posted: 27 Apr 2018 04:10pm
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My thoughts as a relative newby who has just finished putting a system at my cabin:
1) Agree with Steve S - definitely get a larger refer, like the Danby 10CF, I did and t was the right choice
2) Good idea to oversize and overspend (to a point), buy good quality stuff and you won't regret it
3) No doubt Creeky is right regarding lithium batteries, but the cost was too much for me at this point in time. i got some good AGM batteries that will give me 10 yrs, at which time Lithium should be very reasonable from what i hear...
4) as Creeky said, it is easier than you think starting out! Have fun!

creeky
Member
# Posted: 28 Apr 2018 08:59am
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Have a look here. This is my 24v system. You probably need a bit more battery. A slightly larger inverter. This kit ships with a 375. Probably enough for you. But a 500 wouldn't hurt either.

Of course I don't ship to the US. But you can see clearly the pieces I use. And by downloading the simplified schematic on my website you'll be able to chart what you need.

Wilbour
Member
# Posted: 28 Apr 2018 10:07am - Edited by: Wilbour
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"The proof is in the pudding " as they say and, unfortunately, most people are not fully satisfied with the idea that any one system "should" handle their specific needs.

That's why I will be posting updates on my solar setup as it progresses.

I have committed to the system that Creeky has outlined above from Creeky himself.

He does know his stuff but for people who have a hard time believing what is written i will post videos online

My requirements are a little less than TFG outlined but close.

As for the ongoing arguments about lead vs lion I get it. Who would want to replace their working lead batteries at a cost right now? But if you are starting up or in need of updating your system then lead is a tough argument to make and win.

At any rate, I should have something to report by next week.

Notes
Member
# Posted: 28 Apr 2018 11:13am
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I don’t mean to come down on lithium. I came within 24 hours of purchasing 2 sets of Chevy volt packs. You DIY guys are moving this Technology forward and I respect that. I pulled the plug after finding out my homeowners insurance would not cover me and talking to the volunteer fire department and they said at my own risk, they would just let it burn and not even try to extinguish. Hope things improve in a few years when my lead is dead.

creeky
Member
# Posted: 28 Apr 2018 01:44pm
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I would like to see even one report of chevy volt fires.

There was a crash test fire where cause was never found. But there hasn't been a report from actual cars that I've seen.

For homeowners, there are a number of home systems that come fully compliant. Tesla, LG Chem, Samsung are available today. I'll happily sell you a fully compliant LG Chem.

PS-thanks for leaving those packs for me!

Steve_S
Member
# Posted: 28 Apr 2018 01:58pm
Reply 


Quoting: Notes
I pulled the plug after finding out my homeowners insurance would not cover me and talking to the volunteer fire department and they said at my own risk, they would just let it burn and not even try to extinguish.


Just goes to prove how much ignorance is still out there when it comes to this area... As for the "We'd let it burn and not even try" line well... that's quite something isn't it... If they put THAT on paper, a lawyer could have a field day with it, as they are now picking and choosing what residences they would put a fire out on... There is more risk from all the plastics, foams, adhesives, household chemicals (many of which can be extremely volatile and highly explosive) and more within a home or attached garage.

ChuckDynasty
Member
# Posted: 29 Apr 2018 08:47am
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Quoting: Steve_S
"We'd let it burn and not even try"


I've read a story where a volunteer fire dept. let a home burn because the home owner didn't make a monetary contribution to the dept.

ChuckDynasty
Member
# Posted: 29 Apr 2018 08:53am
Reply 


Regarding homeowners and umbrella insurance...I've found that a company has it's guidelines and if you don't meet them they will not insure you or renew you. You may have to talk to 5 different company's to find the coverage that you want.

Wilbour
Member
# Posted: 29 Apr 2018 11:57am - Edited by: Wilbour
Reply 


Well so far we have learned a lot from this thread. Some info doesn't pertain to the original post but here's a list.

Upfront cost : lead is cheaper (specially if they are someone else's trash)

Dependability : lithuim will out perform lead as the tech stands today.

Insurance : check, check and check again! Re sign with someone new if needed.

Volunteer fire department : PAY THE USER FEE ( and dont make passes at the fire chief's wife. I read Chuck's related story and there must me more than what's being told)

ICC
Member
# Posted: 29 Apr 2018 02:29pm
Reply 


Quoting: ChuckDynasty
I've read a story where a volunteer fire dept. let a home burn because the home owner didn't make a monetary contribution to the dept.


Some places require a payment specifically to the fire dept. That could be what you have heard. If you don't pay them they can let your place burn. I have also heard of that happening. In a way you can't fault them as if they fought a fire at an unpaid address they would be setting a precedent and others might decide to not pay while hoping the fire dept will still come to their place.

Other places like all the places I have owned property have the fire dept. fees built into the tax base and they will cover everybody in the tax area.

ChuckDynasty
Member
# Posted: 29 Apr 2018 05:46pm
Reply 


Yes, I think you're right. Read something a few years ago. Could even have read it here. lol

Quoting: ICC

Some places require a payment specifically to the fire dept. That could be what you have heard. If you don't pay them they can let your place burn. I have also heard of that happening. In a way you can't fault them as if they fought a fire at an unpaid address they would be setting a precedent and others might decide to not pay while hoping the fire dept will still come to their place.

Other places like all the places I have owned property have the fire dept. fees built into the tax base and they will cover everybody in the tax area.


Wilbour
Member
# Posted: 29 Apr 2018 10:17pm
Reply 


Since you guys asked

http://www.nbcnews.com/id/39516346/ns/us_news-life/t/no-pay-no-spray-firefighters-let -home-burn/#.WuZ6iogvyM8

"Firefighters in rural Tennessee let a home burn to the ground last week because the homeowner hadn't paid a $75 fee."

"Cranick, who lives outside the city limits, admits he "forgot" to pay the annual $75 fee." (forgot was in quotes by the original article indicating a doubt that it was truly forgotten leading the reader to believe there is history with regards to the owner and his respected FD)

"The fire department's decision to let the home burn was "incredibly irresponsible," said the president of an association representing firefighters.

"Professional, career firefighters shouldn’t be forced to check a list before running out the door to see which homeowners have paid up," Harold Schaitberger, International Association of Fire Fighters president, said in a statement. "They get in their trucks and go."

Like I posted above, there is a lot more to this story, after all, the article leads you to believe the owner's 3 dogs and a cat burned in the fire. What people would just let this happen? (Don't answer - that was a rhetorical question)

But back to the original post....

ICC
Member
# Posted: 30 Apr 2018 11:37am - Edited by: ICC
Reply 


Apparently, there are many places around the USA that have subscription fire departments, many in the rural US South, but I also found cases in rural AZ. These cases where a home burns because nobody paid the subscription fee are somewhat analogous to health insurance premiums. If the doctors tell you that you have cancer it is too late to buy or upgrade your health insurance. And forgetting to pay the fee to the fire service will produce much the same results as forgetting to pay the health insurance premium, or the car insurance premium, etc. It's rough but it is what it is. People do have the power (votes, get involved, etc)to change things like that. Make it a county thing and charge everybody for fire protection in their taxes.

I'd like to make it clear that I do not agree with a subscription type of plan. I believe it should be included in property taxes for everyone. When everybody pays into the firefighter fund the costs should be reduced for all. In locales with subscription plans only about 70% pay the subscription fee on average. Some areas bill the nonsubscribers if they come to a fire. However, I read that maybe only 50% of those people pay the bill, meaning others end up paying the costs.

If fire protection fees are included in the property taxes a person could still 'forget' to pay their tax bill. However, rather than let the house burn, the fire will be put out. If the taxes are not paid for 2 or 3 years then the county starts the process to take over and sell the property. So in the end, the county gets its money and the irresponsible property owner pays.

cspot
Member
# Posted: 30 Apr 2018 07:42pm
Reply 


I agree ICC. I never heard of subscription plan for fire protection. I do not like big Government, but fire is something that should be part of the local taxes.

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