Basic cabin power: generator + batteries + inverter?

Discussion in 'Off Grid Living' started by Capt.Canuck, Aug 2, 2014.

  1. Capt.Canuck

    Capt.Canuck Monkey

    We are just finishing up a no-permit, off grid, water access only cabin.


    It is wired for power, and so far we have a Honda eu2000 generator giving us power when we need it.

    At some point I'd like to do solar, but as a first step I'd like to set up a battery pack system and pure sine wave inverter that I could charge with my generator when required - so that I wouldn't have to run the generator each time we have simple tasks that require power.

    I'd also like the system to be as maintenance free as possible, and OK to leave in place in very cold winters (when it would not be used).

    Is this doable? What equipment would I need to make this work, and what should I budget in terms of cost?

    Thanks in advance for the help.
    Motomom34 and Dunerunner like this.
  2. Capt.Canuck

    Capt.Canuck Monkey

    Thanks for your reply, I appreciate the perspective.

    Regarding your first point, is it your feeling then that any power system in a weekend use cabin like ours is pointless, and likely to go missing unless well hidden when not in use? Would solar panels act as a "come steal me" sign, or an advertisement to come looking around?

    In light of this, maybe I could dig/build a small hidden cellar some distance away from the cabin to store the batteries and inverter when we aren't there in a waterproof Pelican case or something buried. Based on your comment about not recommending leaving them there through the winter, I could take them out in the fall and being them back in the spring.
  3. ghrit

    ghrit Bad company Administrator Founding Member

    Can it be done? Yes, emphatically. For any sort of detailed "advice" that will be worth what you pay for it, we need to know a lot more. What loads are you planning to put on the electrical system? That will dictate the battery, solar panel, and inverter size and cost. (Might also put a squeeze on your ability to move the system in and out of the area at the season's change.)
  4. VisuTrac

    VisuTrac Ваша мать носит военные ботинки Site Supporter+++

    Depends on your use of the cabin.

    I'm going to assume that this is a summer cabin only.
    That you are going to use it a couple of weekends a month and possibly once for about a week to 10 days. each season.

    If that is the case, you already have your power supply. The genny.
    All you will have to do is plan your activities around when you want to run the generator. No additional costs required.

    That way, you can spend more of your dollars on other camp requirements.

    Of course, if you plan on spending more time than that at the cabin and want more city comforts .. we need to know that to provide you advice.
    AmericanRedoubt1776 likes this.
  5. Capt.Canuck

    Capt.Canuck Monkey

    I think the message here is that I need to finish the cabin and spend some time there with the family, to get a better idea of what our power generation needs will be.

    Thanks guys.
    Motomom34 and ghrit like this.
  6. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    As one who actually LIVEs out in the Alaskan Bush, and generates ALL my own Power, the quick answer is ABSOLUTELY. The long answer is, There are considerations that make this kind of System, Operational, even for Long Term Hibernation. Battery Type will be VERY Important, here.

    Gell Cells and AGM Batteries will not fair well in Freezing Temps.
    Freezing will kill a Battery Dead in short order, and also will likely cause the Case to SPLIT, and allow the Electrolyte to leak out.
    Flooded Lead Acid Batteries will NOT Freeze if they are kept Charged. Depending on Location, and ability of Southern Facing, No obstruction, Solar Panels, to keep at least a residual Charging Current, on them, they will do fine even at -15F, for extended periods. I have neighbors that have Solar, that keeps their Flooded Cell Batteries going all Winter Long, with just enough charging current, to overcome the Self-discharge Rate of Flooded Cells. During our LONG Day Summers, these Solar Systems are big enough to supply 90% of their Summer Power, except for running the Fish Freezers. For those, they run the Genset. Those folks that live here, Year-Round, must use the GenSets, to maintain the Electrical Power for their Operational, and Living Needs, When you only have 6-7 Hours of Daylight, and most of those days, are Rainy, and overcast, there really isn't enough Power, generated, to run anything except to keep the Batteries, Topped Off.
  7. Tevin

    Tevin Monkey+++

    I also run off a solar/battery arrangement. The short answer is yes. It's very doable. But there are some caveats:

    Get a charge controller with a temperature compensator. It costs a little more, but it will adjust the charge up or down according to the temperature.

    I'm not sure how large a system you are looking to set up, but anything over a few hundred watts starts getting more complex, especially if you bring inverters and gas generators into the picture. Such a project is not for first-timers. Solar is simple in principle and complicated in practice. You know your own abilities; keep in mind you're depending on this system. It's not a hobby.

    You can leave the system all winter and the solar will keep the charge up. The problem is that if something goes wrong you will not know until the spring when you return and find a bank of dead batteries. I suggest if you expect to be gone for a long time, take the batteries with you and keep them charged at home. Lugging batteries back and forth is a pain but its the only way to assure they don't crap out when you need them the most.

    Unfortunately, solar with batteries is not a "set it and forget it" arrangement. You will have to commit to some level of upkeep and attention.
    AmericanRedoubt1776 likes this.
  8. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Just looking at the posted pix I SEE Trees = SHADE .
    Where is this Cabin Cap Canuk ? Mine is on Vancouver Island , solar & airtight Power & heat . No cell , TV maybe if it's clear but we don't waste power to hear bubble heads , Radio but the cabin is for if the weather changes & a storm hits. There is a sign in the cabin , replace the food you ate and stay safe . A few know it & have used it. My coldest might be -10c MAX for a few days , & if the battery's are charged , they don't freeze but power output is low.So they are under the cabins floor buried in the dirt for cool Solar panels are in the skylights facing south . Power is for led light, to read ! Lots of books up there & if you take one you owe two in return ! Out house also has an LED with outside lighting to it. Basic storm shelter . Bears & wolves have been there , but if the place is keep food in cans sealed & MT cans removed when you leave seems they can't read. 12 volt system , all for just leds & to charge the GPS , radios using a buck converter if i need higher voltage . Main switch shuts all power off But Solar to battery is always charging daylight.
    DarkLight likes this.
  9. -06

    -06 Monkey+++

    A bud and I are talking about building a "BO trailer". Dual axles only about six feet wide with sealed bottom for storage and batteries/controller. Above the boxes will be solar panels that can be turned toward the sun(unfolded) for max exposure. The 4 wheeler can pull it most anywhere or a vehicle. That way it can be used at home and a remote location.
  10. DarkLight

    DarkLight Live Long and Prosper - On Hiatus Site Supporter

    @Capt.Canuck - @Cruisin Sloth beat me to it but the very first thing I thought when I saw that cabin was "Where are you going to put those solar panels because there ain't no sun around that cabin and dapples of sunlight obviously won't cut it?" Are you planning on doing some/a lot of pruning/thinning?

    Again, not to rain on any parades but without more info that corrects my initial gut reaction, I would say I didn't see how it would work. Could it, conceivably, in theory? Yeah but I don't see how "as it sits".
  11. Capt.Canuck

    Capt.Canuck Monkey

    Lots of useful information in this thread, thanks guys.

    It is heavily treed near the cabin, but my thought was that I could run a heavy gauge cable about 75 feet and be in a very bright clearing near the waterfront.
  12. Cruisin Sloth

    Cruisin Sloth Special & Slow

    West Coast
    And a come see my stuff DOCK !!
    Heavy cable cost heavy wallet . Do a higher voltage system & run thinner wires , Or have a 214B Helio do a tree manicure .
    Got to know the basics of where are YOU ? Summer only , cuz mine is NOT for summer , only wet winter storm months , so low sun & power for 3 nights , but will recoup in weeks of no use . The Out house & horse bedding area are the first who will drop power if you abuse. Yes theres a stock of feed for the horses in Steel Galvanized garbage cans , restocked with an ATV in better days. Trappers / Natives and many more we know have used it . Not much stuff has found legs . Many a box of stuff has been left at the farm/ranch . Neigh-bores who are grid dependent asked if we need the food bank when they see the boxes left at the driveway gate house :) ..
  13. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Better Option is to Put the Solar Panels down at the Water, and a cheap Inverter, there, powering a 4:1 Transformer that boosts the Voltage to 480 VAC... then run the 480Vac up to the Cabin, thru the Trees, with two strands of #12 wire.... Then Backwards thru another 6:1 Transformer, that brings the Voltage, back down to 80Vac... Then Rectify it, and shove that into an Outback MX80 MTTP Charge Controller, that has a three State Battery Charger, built-In.... With the above System you can run the 480Vac for a few MILES, if needed and still get significant Power at the Cabin End. Now for the Drawback..... Siting the Panels, at the water, leaves them sitting out there like a GIANT Neon Sign, that says "Hey anyone, passing by, There is Nice Technology here to come STEAL, if you think you can"..... Where as if you chop a few trees down, for firewood, and clear a bit of Land, around the cabin, but leave a strip of trees, at the water, to hid the rest of the place, your technology is all at the cabin, and you can do away with the cheap Inverter and Transformers.
    AmericanRedoubt1776 likes this.
  14. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Man YOU have LOSS /LOSS/LOSS every change !! plus 48 volt's and under is no permit (Gray of Grey Area ) . 480 $*) !! volts Dang , .
    Lets see those curly's !!!!!!
    Last edited: Aug 5, 2014
  15. Tevin

    Tevin Monkey+++

    @BTPost ...dude, you know I respect you. But oh holy tap-dancing Jesus! Are you serious? If I'm following you correctly, you're converting the power five times before it hits the batteries, then one more time if you want 120 VAC in the place. When it gets to the end of this Rube Goldberg maze, you'll be lucky to have 25% of the energy put into it, not to mention all the points of failure.

    And good luck finding a 480 volt transformer that will handle any reasonable power that isn't three phase and doesn't require a forklift to install.

    My solution: A 75 foot run is a reach, but not out of the question. Buy a long roll of 6 gauge or even 4 if you think you can work with it and set your system up for as high a DC voltage as your equipment will allow. Example: If you have four, 12 volts panels, send 48 volts down the wire to the charge controller. A good MPPT controller will very efficiently do the conversion back to 12 volts for your batteries. Bury the wire in the ground and take the solar panels down and store them out of sight when you are gone for a long time. This will eliminate security concerns.

    There are tons of on line calculators that will tell you what your voltage drop will be. For 48 volts DC run through 75 feet of wire, the loss runs between 1%-6% depending on the current and type of wire. That's got to be better than a mess of transformers and inverters.

    Voltage Drop Calculator

    The whole deal will cost less, be less complex, and be waayyy more efficient.

    And BT, I still think you're ok!

    Last edited: Aug 5, 2014
    AmericanRedoubt1776 likes this.
  16. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Once the Panels have been seen , there a target ! Roof mount them and buy way more Watts than required . Settle on power from shade & weather. Summer camp right ?Do some tree pruning so it gets southern exposure sun from 10-2 . What are you trying to power .
    Im with Tevin with MPPT & higher voltage to have less line loss, but 24 volts , if 12 is needed for lighting in LED's use a buck transformer ,
    Last edited: Aug 5, 2014
  17. BTPost

    BTPost Stumpy Old Fart Snow Monkey Moderator

    Well Tevin, If you need to move Electrical Power a long distance, then this is the most Efficient way to do it. It WORKS... and 500 or 1Kw 120/480 Vac Transformers are "Dime a Dozen" in most Scrap Yards. They are called Control Transformers, and are used quite often in Industrial Applications where you have LOTS of 480Vac Motors & Controllers, but the associated Control Logic runs at 120Vac, or some DC Voltage. They put in a Control Transformer to get 120Vac from the Mains, and then if they need DC they put in a DC Power Supply off the Transformer. There are a few Hydro Systems around here that use this method to move Power a couple of hundred Yards from Turbine to Cabin. They use an AC Alternator, feeding the Transformer on the Sending End, and a Transformer feeding a Rectifier, and MX80 on the Receiving End. These run 24/7/365, and provide 200-500 Watts, continuous Power. You need to get out more, and see what folks are doing, out in the bush.....
    AmericanRedoubt1776 likes this.
  18. Tevin

    Tevin Monkey+++

    In your hydro and wind turbine examples, the power source is creating AC from the get-go and located quite far from where the power will be used. And of course, an AC power source will need to be rectified to DC at some point if you are going to charge batteries. There is no way around it.

    That is worlds different than converting native DC to AC for the sole purpose of shipping it 75 feet (which itself is nowhere near as much of an engineering challenge as "a couple of hundred yards"), then converting it back to DC, which it was in the first place before you ran it through two transformers, two inverters, a rectifier, and a charge controller...every one of which nibbles off some juice. And I'm supposed to believe all of that hardware and complexity and inefficiency is a net-plus over the a 1%-6% loss from sending raw DC through 75 feet of straight wire? Oh my.

    You are 100% right that sending electric across large distances requires AC and by default transformers. I guess we simply disagree on what is considered a "large distance".

    But I still think you're cool, BT. [beer]

    AmericanRedoubt1776 likes this.
  19. Tevin

    Tevin Monkey+++

    Technical advisory: Transformers do not work on DC power.
  20. ghrit

    ghrit Bad company Administrator Founding Member

    But AC is not required these days, there are some very damn high voltage DC transmission lines in service where corona losses are higher than I(sq)R loss. Uv cuss, this is not even close to practical for prepping.
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