New member looking for a Winter solution

[Latt51]

Hi, I am a new member looking for advices for winter setup.   
We are 8 guys who installed a brand new solar system last summer.  Worked well all summer BUT barely avoided a desaster during its first winter. 
The system is installed at a fishing camp (51 deg North) with no access from september to june.  The 4 x 400 watts panels installed on the roof were covered with snow far too long for the 8 batteries (2 banks of 4x6volts FLA Rolls S-605  460 AH). The magnum inverter was switched off but not disconnected and the Classic 200 SL was left ON with the intent it would keep the battery fully charged.   When we got to the camp in june,  the Classic was OFF and each battery was below 1 volt! Using the generator along with a separate battery charger I managed to get each battery to a decent 5 volts before reconnecting everything and restarting the Classic. 
Any suggestion to keep the batteries healthy through next winter ?

[ClassicCrazy]

Wow - that is a bummer .
Did you test to see if the Magnum inverter was drawing current from the batteries even when switch off ? Do you mean software off or turning the breaker for it off ? You would think that if the breaker was off no current. 
Do you know that there are no other loads on the system ? I am not sure about that SL model - do you have a Whizbang on it or does it take one ?
I would want to know if there is any load on your system other than the Classic itself.   The Classic literature I just looked at shows  standby consumption from 2.5 to 4 w .  So with no power coming in at all for 30 days that would be 2880 wh if I did that correctly . Hope I am doing the math right but from what I calculate with no PV power input at all and the classic on at max 4 watts that would mean your batteries would be down about 50% in two months .
Curious what angle you have your PV at ?  Maybe putting some PV totally vertical so snow could fall off easier and using a small controller for winter with not much of a no load draw would be an option to float them ?  Otherwise it sounds like it is better to just fill the batteries up before you leave and disconnect everything from them ?  Or maybe another control ( or the Classic itself with Aux )  on a contactor or relay that will disconnect the Classic and everything if it goes below a certain voltage ?
Maybe some one else will have experience with this  - these are just some things I thought of just now.

Larry

[ralph day]

Before you leave for the winter hang a panel or two on a south facing wall at 90deg.  No snow load and power enough to keep batteries topped up over the winter ( if the snow on the ground doesn't reach that height  )

Ralph

[KyleM]

Before you leave for the winter hang a panel or two on a south facing wall at 90deg.  No snow load and power enough to keep batteries topped up over the winter ( if the snow on the ground doesn't reach that height  )

Ralph

This is a great idea!!!    Also it might be worth setting up a low battery disconnect just in case.   There are many ways to get this done, and it sure beats coming into camp and finding dead batteries.

http://midniteftp.com/forum/index.php?topic=3714.msg35955#msg35955

Kyle

[Vic]

Hi Latt51,

Often,  one would expect Flooded Batteries to be damaged by such low discharges.

Also,   the freeing temperature for the electrolyte in a dead battery,   is not much below the freezing point for pure water.   One page one of the following Link is a table of freezing points,   verses the battery charge level:
https://www.trojanbattery.com/pdf/WP_DeepCycleBatteryStorage_0512.pdf

Perhaps,  your batteries did not freeze   ...   but you might want to check for physical damage to the battery cases.   It can be risky to charge batteries which are still frozen,   but,  it appears that you avoided doing this  ...

FWIW,   Good luck,     Vic

[Latt51]

Thanks all for your rapid reply.. much appreciated! 
The 8x6volts batteries are configured in 2 banks in parallel of 24Volts.  With 120 VAC fridge, freezer, and 3/4 hp water pump, the Magnum 2824 is directly connected to the batteries with 80 A rating cables. Since the other owners of the camp are not much into electrical works, I want to avoid manual connections and handling every spring and fall. 
I would go for adding an extra PV panel installed at 90 deg facing south with foot of the panel 8 feet above ground.  I would need a panel with enough power to feed the Magnum standby drain current with all AC loads turned off +  enough power to feed the Classic 200SL standby drain current which would remain powered ON.
I read about minimum PV voltage for proper battery charging.  My summer config is 2 banks in parallel of 2 LG 400 Watts (LG395N2W-A5) panels which deliver total 20A at 80 Volts.  What should be the  minimum requirements of a winter PV to keep the batteries fully charged all winter ?

[Latt51]

Any suggestions for panel brand and Model that would do the job ?

[tecnodave]

A single panel that is 96 cell will work well for wintering if you turn off the summer panels. The Sanyo HIT panels have a high MPP of 53.5 volts and will work well with the classic and a 24 volt bank. A 72 cell panel will not have enough voltage to keep the classic happy. If you use this approach, do turn off the summer panels at winter shutdown and turn off the winter panel when you start up for spring. The two arrays will not work well togather

[littleharbor2]

Why is the Magnum left on over the winter? Really should have a circuit breaker allowing you to shut down for maintenance, etc.

[FNG]

The Magnum will draw around 3-5 watts when off, So that equates to a LOT of power over a period of time

My suggestion is, Shot off the DC breaker to the Magnum, And as others have mentioned if the modules can not be moved to a vertical orientation hang one or two modules vertical and leave them on for the winter

[mcsarge]

We almost had the same issue, but luckily our system never dropped below 50% for the batteries. In order to combat that, I took 2 of the old 80 watt panels from the system we replaced and mounted them on the wall of the cabin under the roof overhang facing south-south east and high enough they would not get drifted on. I ran those two into the old MPPT controller and then through the WhizBang Jr. to the battery bank. So when the panels on the roof get covered with snow, like they did last year, the wall panels will make enough energy to keep the batteries topped off. We leave the Midnite 150 and my communications system running all winter - those together use about 0.5A or about 290 Watts a day, so the winter panels should be able to help span the periods of time the main panels are covered with snow.

[richard@ttmg.com]

This is how I handle winter charging. I am at lat 53N and long -109 and hane used this technic as high up as 59 deg N.

I use a fuel cell generator. I is powered by methanol. I use 2- 28 L jugs of methanol for the whole winter. It works wonderful.
If I need to I can put in as many as 4 28L jugs of fuel. Each liter generates about 1000W of power.
The unit maintains battery voltages but cutting in at 12.3 volts and turns off in 3 hours.
It controls its own internal temperate by going into anti-freeze mode.

The units are made by EFOY.
Take a look.