closeing my off grid cabin for the season ?

wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭

What should I do with my battery for the winter?

I could just take them home I have 2 230 ah 6v gc battery.  

 Im thinking the solar panels will be covered with snow for most of the winter.      I was thinking I could mount a 32watt panel to the side of the deck to keep the battery  charge up , when the snow is on the roof.

do I need a cc for a small panel?

 I could turn off the main system and just charge with a small 32 watt panel and a pmw cc .

thanks john



Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .


  • BB.BB. Super Moderators, Administrators Posts: 32,999 admin
    I would suggest a 2% minimum rate of charge for an over winter battery bank (no loads):
    • 230 AH * 14.5 volt charging * 1/0.77 panel+controller derating * 0.02 rate of charge = 67 Watt nominal "float
    If you wanted the minimum then 1% rate of charge can work OK (or ~33 Watt panel--Like you suggest).

    Mount on a vertical wall (or post/tower) to shed snow.

    Have the battery bank relatively fully charged before you leave. Turn off all loads. Make sure you "trust" the charge controller (settings, reliable), and let it go. You want the controller to mostly be in float--Should not to Absorb charging during winter (keep water usage low).

    Cold Lead Acid batteries have lower self discharge current--So even if the panel(s) are covered during part of the season, as long as the batteries are cold (freezing or below)--You should be OK.

    Of course, there is always the concern with security (theft). Taking the batteries home and putting them on a nice Battery Tender or Battery Minder to float them through the winter would be fine too (take solar panels down and back home, or at least lock in the cabin).

    At least that is my suggestion--I live near San Francisco--So I don't really have cold weather system experience.... Others can chime in with their suggestions.


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Mountain DonMountain Don Solar Expert Posts: 494 ✭✭✭
    I don't know where you are located. We have a cabin in the mountains of northern NM. It will get snow by mid December and hopefully will have snow until April.  I have left the system to run itself since 2009. The inverter is left disconnected and the DC cabin circuits left disconnected. The charge controller is left on. The batteries are watered and EQ'd in November. We make monthly visits for 3 day weekends once a month over winter; a week or so Christmas to New Years. The batteries are always full when we arrive. 

    Our PV panels are pole top mounted, set at an angle commensurate with 35 degree latitude. I leave them at the "winter angle" all year long. They shed snow readily enough. If you are further north that will shed snow even better. We have more sun than clouds and there is never more than a couple / three days of snow sitting on the panels. I'm going by the CC data recorder records for that assessment. 

     A fully charged FLA does not freeze until the temperature hits -90 something F. So as long as the system continues to function we are good. 

    Of course I am trusting in technology.  I have used higher quality technology rather than cheaping out on low cost brand-X equipment. That has worked since 2009. Except for the lightning strike, but that is another matter, another topic. The important thing to me, is that winter does not seem to be a problem; no lighting and snow impassable roads keep the riff-raff away. Cold temperatures retard FLA self discharge. 

    OTOH, a small panel and controller could easily handle the self discharge. I used a small 40 watt panel and CC for many years on the old RV we had.  That kept the batteries fully charged over the winter.  Again it is trusting in technology. 
    Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M
  • ramlouiramloui Solar Expert Posts: 109 ✭✭

    My cabin is located in northen Quebec and I leave everything there for the winter. I turn all of the loads off, including the inverter. As Mountain Don said, make sure the water level is ok an equalize your batteries on your last visit. The last thing I do before leaving for the winter is to tilt 2 of my 6 panels to vertical to shed the snow. When I show up in the spring, batteries are always 100%, I just flip the switch and everything works without missing a beat.

    Good Luck!

    Louis R.

    Off-grid cabin in northern Quebec: 6 x 250 W Conergy panels, FM80, 4 x 6V CR430 in series (24V nominal), Magnum MS4024-PAE
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭

    At home last year the solar panels where covered with snow for 3 months .

     My cabin was colder and had more snow around ,  I was told there was a 16' drift across the road 2/3rd of the way up .

     There is a snowmobile trail that runs  the lenth of  my ridge  about 150' behind the house at 3000 ' so there is some traffic.

     I have a 24x40' garage all closed in  with siding ,   I  hope  the hunters don't shoot up my cabin/ trailer  / new building this year.

     The panels are all most flat  with a  3 on 12 pitch .

     Could I add my 32watt flex panel with out a cc  as back up and keep my 210watts of solar on  also ?   


    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • upa123upa123 Registered Users Posts: 17
    edited October 2015 #6
    We leave our 3k ground array, inverter, charge controller up and running all winter mostly so I can power a cell based wifi router, IP thermostat and a forced air furnace on demand. We will go every other weekend during the winter and like the convenience of being able to call up for heat to pre warm the house during the 90 minute drive from our city home. The only load we disconnect while we are away in the winter is refrigeration. So far so good, we find even if there is a good snow as long as there some sun in the next day or two it will burn  the snow off the panels eventually. I think the inverter only had to disconnect itself once in the last 3 winters because the battery bank hit my low voltage threshold.
  • BB.BB. Super Moderators, Administrators Posts: 32,999 admin
    Note that the default battery cutoff voltage for most inverters is way to low (~10.5 volts @ 12 volt bank)--And will generally damage or kill the battery bank. If you can reprogram for higher cutoff voltage, I would feel more confident leaving an inverter up and running for 3 months without anyone there.

    And/or find a small AC inverter to run the Internet loads (or a DC to DC converter to run the typical DC input). Anything you can do to reduce overall power usage (those 24x7 loads add up pretty quickly--especially in winter/bad weather).

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • 706jim706jim Solar Expert Posts: 500 ✭✭✭✭
    I've left my batteries on my island camp for the past 20 years. Winter temps go as low as -20F there and panels are snow covered for approximately 4 months. The panels and charge controller are connected and the batteries are fully charged in the spring. I think your biggest concern would be vandalism rather than anything bad happening to the batteries from the cold.
    Island cottage solar system with 2500 watts of panels, 1kw facing southeast 1.3kw facing southwest 170watt ancient Arco's facing south. All panels in parallel for a 24 volt system. Trace DR1524 MSW inverter, Outback Flexmax 80 MPPT charge controller 8 Trojan L16's. Insignia 11.5 cubic foot electric fridge. My 29th year.
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭

    I think I will just run a small back up system  that I have on hand and try to go up every 3 weeks or so .

    The heat runs 1/2 the time if its in the 20o  so its cold .

     Next winter I will  work inside the house,  if I can get up there ,  and run a wood stove.

     Do you guys have  home owners insurance on your cabin/land ? and what dose it run?

     My agent tells me , HOI for my place is 860 a year.    seems like a lot for a garage ?

      And it dosent really cover very much .       John

    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
  • vtmapsvtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    wellbuilt said:

     My agent tells me , HOI for my place is 860 a year.    seems like a lot for a garage ?

      And it dosent really cover very much .       John

    A dwelling that is not occupied full time by an owner is much much riskier to insure.  A building under construction has some different risks, but is also risky to insure.   Our HOI dropped more than 25% (and covered more risks) on the day we moved into the house.

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • wellbuiltwellbuilt Solar Expert Posts: 763 ✭✭✭✭

     I mite just let the hoi slide this year , If they brake into the trailer im not covered , if they steal the solar equipment im not covered , hit by lightning im not covered , If the garage burns down they will cover me for a % of the value ?  WTF                   If someone get hurt on site they will cover me in a suet ,  but I have WC on my guys .  Im getting burnt out   with this .

    Out back  flex power one  with out back 3648 inverter fm80 charge controler  flex net  mate 16 gc215 battery’s 4425 Watts solar .
Sign In or Register to comment.