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Small Cabin Forum / Off-Grid Living / Solar or Generator
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lindenknight
Member
# Posted: 23 Nov 2021 21:11
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I have a small cabin in Arkansas that I power with a Honda EU2000i generator. I use about one gallon of gas per day and run it about forty days per year. Does it make any sense to switch to solar (other than saving the planet, of course)?

gcrank1
Member
# Posted: 23 Nov 2021 21:23
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It depends, lol
Ime the key to efficient off-gridding is not more energy production but energy conservation.
What are you powering and for how long?
And how tired are you of hearing the gen run for low loads?
And do you have good sun exposure thru most of the day?

travellerw
Member
# Posted: 23 Nov 2021 22:11
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There is another option..

If your loads are really light (like just lights and the odd pump run), then you could add a portable battery solution.

The Honda would still be used for powering big loads (maybe a blender). The portable battery runs everything else. At the end of the weekend, you bring it back home and plug it in to charge for next time. Many support a small solar panel to help carry them through the weekend.

It really makes no financial sense as you burn about $150 in fuel a year. A portable battery solution is probably double that (solar setup 10 times your yearly burn). However, you don't have to listen to the generator (my wife says you can't put a price on that).

lindenknight
Member
# Posted: 23 Nov 2021 22:19
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6 or 7 60 watt equivalent LED bulbs, a ceiling fan, plus a couple cell phone chargers. About 4-5 hours of good sunlight daily. I get down there about once a month for about a week’s stay. I would think that 3 weeks of charging would store enough juice to get me through a week down there but how many batteries and what type.

lindenknight
Member
# Posted: 23 Nov 2021 22:52
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Thanks, travellerw, I have the Honda in an old horse barn a ways from the cabin, and the noise is not too noticeable depending on which way the wind blows. I have several battery powered lanterns for the rare occasion when I don’t bring the generator. I will probably stick with this setup.

gcrank1
Member
# Posted: 23 Nov 2021 23:27 - Edited by: gcrank1
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6 or 7 60w equiv. led lights, thats a Landing Strip!
We have a 16x24 one room total off-grid, dry cabin. I wired up typical, cheap 120vac Edison base pull chain fixtures for 4x18w led bulbs; we rarely use 2 at a time and the 2nd one for only a short time. But they are located around the place so we can have good light wherever we are.
They draw so little it hardly matters, same with usb ports and device chargers.
My med size box fan and small clamp fan, both 120vac, use less than the cheap ceiling fan, but its in so we use it some (the smaller, lower draw fans got more use last summer).
An old am/fm radio and a tv/vcr player combo about 20yrs old keep us entertained if we need a modern fix.
I have been running off 2x100ish ah Old deep cycle batteries for about 1.5yrs now (we are mostly 3 season, often several day trips/wk, some overnights) with only a 300w pure sine wave inverter (it has low 'overhead').
This runs my cordless tool chargers too; actually anything within its power output without 'issues' like the cheap MSW inverter have (believe me, they arent the bargain they may appear).
Anything 'big', like the 700w microwave, toaster, corded power tools, etc run off the 1700/2000 inv/gen.
When it runs, which isn't much, the automotive bat charger can be on to supplement the 600w solar (6x100w panels). The solar, a cobbled rats nest, came with the place, venturing a guess it would easily be about a $2k+ system to install now?
These led lights are game changer, along with usb port driven stuff, cordless tools and inv/gens.
The 'traveling battery' thing works, take it home to Fully Recharge with no guessing; and if you dont want to break your back get a 100ah LFP which easily equals 2, even 3 FLA bats for usable amp hours (if you use the recommended top 30% max ah's from the FLA for battery health. Only use 50% from an FLA occasionally if you want it to live long). The LFP is expensive, has way more usable ah's, much lighter and a longer life span; way less expensive than building a solar system for relatively light duty use.

Steve_S
Member
# Posted: 24 Nov 2021 03:19 - Edited by: Steve_S
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For something this small, seriously, people this is what Bluetti's and portable power stations are all about. There are MANY versions with various sized batteries and with add on ones + add on solar (plug in and go) etc...

https://www.bluettipower.com/

There are MANY Brands and variations on the market. Seek out only ESTABLISHED products that are NOT being crowdfunded or anything tat has been in production for over 1 Year at least (debugged just in case).

Best portable power stations of 2021
Get power whenever you need it with a battery-powered portable generator.

https://www.cnet.com/home/energy-and-utilities/best-portable-power-stations/

Best part of these is you can use them in you house/apartment, boondocking, camping so in many situations where another generator or alternate energy source could be a PITA.

AVOID RENOGY at all Costs !

Brettny
Member
# Posted: 24 Nov 2021 08:10
Reply 


Honestly if I didnt want to run a fridge I would be useing one of these portable battery packs and charging it at home. If I stayed longer than the portable pack lasted running lights I would buy a $200 1kw inverter generator to charge it.

I have a sportsman inverter 1kw that costs $200 new and have been very happy with it. Uses 0.55gal (a tank full) in about 9-13hrs.

Steve_S
Member
# Posted: 24 Nov 2021 09:21
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https://www.mobile-solarpower.com/full-size-systems.html

https://www.mobile-solarpower.com/ultra-portable-systems.html

gcrank1
Member
# Posted: 24 Nov 2021 10:32
Reply 


As an old school 'component system' guy Im figuring if my solar dies Im likely to go with a 100ah LFP to take home to charge too. My inverter set up wont care if it is hooked up to whatever 'storage' I have, solar or not.
That and the inv/gen and we are good.
Im thinking that a lot of folks that really just need a small, simple solution make it too complicated. When I started thinking 'small rv' type electric it all got better for me.

travellerw
Member
# Posted: 24 Nov 2021 17:19
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Quoting: lindenknight
6 or 7 60 watt equivalent LED bulbs, a ceiling fan, plus a couple cell phone chargers. About 4-5 hours of good sunlight daily


Ok.. This is making the first mistake that almost all new solar users do. You are just guessing (educated guessing, but guessing).

In reality to answer this question you NEED to do a power audit and come up with an exact range of power (Kilowatt hours) you require. This will help you size the batteries to carry your load over your longest expected stay. That is the part of the equation that is most important. Once you have that, you can get into the questions of the size of array required, array topup daily, ect.

The other thing you really need to understand is ANY system has complexity. You can't operate a system by just saying "Well, the batteries went dead, I will start the generator now!" (well, you can, but will be replacing your battery bank very often). Any system requires work and knowledge to operate properly (or VERY deep pockets to automate it all). For most offgrid users, its a sort of hobby. They manage the system, but also work hard to reduce usage.

Now with all that said and based on your "guess" of power usage. Here is some very rough numbers.
Fan = 60W (A complete guess as fans range from 20-100W)
Lights = 28W (60W equivalents are about 4-5 real watts)
Phone Chargers = 10W

So lets put some use numbers in there.
Fan running 5 hours a day is 300Wh/day
Lights, say 4 lights burning 4 hours a day 64Wh/day (I'm averaging here)
Phone chargers is a tough one. This depends on the amount cell phone use, but lets just say you will use 35Wh/day

Add that all up and you need about 400Wh over the course of a day. For Lead Acid batteries you never want to draw them down more than %50, so you need an 800Wh battery to carry your usage for 1 day. To put this into perspective, a pair of 6V golf cart batteries has about 1200Wh (Enough for 1 day, but not 2). You would need 4 6V golf cart batts to carry you over a long weekend (again we are assuming no input from solar like its a cloudy/rainy weekend).

Now if you wanted to use a portable battery like I suggested (and we will use the suggested Bluettipower) you would need at least a 800Wh unit for a 2 day weekend (unlike lead acid batteries these units are rated in what you can safely draw from them). If you reduced your usage a bit you could go with the 715Wh unit for $550, otherwise you need a 1000Wh unit for $899. Thats an awful lot of fuel before you are paid off!

NOTE - I'm doing all this out of my head, so I may have some numbers wrong. Someone please correct me if I got something wrong!

Houska
Member
# Posted: 24 Nov 2021 18:20
Reply 


Another vote for a portable lithium battery. It costs a bit extra, but it adds loads of flexibility.

Bring it from home, charged. Silent power. If you turn out to be running low, plug it into the genny and charge it up a bit, whenever it suits you (noise, etc.) and then use the power when you need it. Frequently run low and/or have lots of sun? Get some solar panels and give it a solar boost. Used little power this weekend? Leave it there (plugged into the solar if you have one). Want power 300 yards further west today? Bring it there for a few hours.

The two things there are *not* good for are sustained high loads (chew up the capacity big time, and depending on specs may exceed the wattage) and sustained small loads *plugged into the inverter*, since keeping the inverter on drains a few watts all the time. If you have such small loads, like a cell booster or similar, worthwhile seeing if you can power it off of DV 5V (USB) or 12V instead. Most of these batteries have a DC output too and you save the inverter overhead.

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