Solar to run a fridge.

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Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    Bulk stage: as much current as the panels & controller can muster to push battery Voltage up to the Absorb set point.
    Absorb stage: Voltage is held at the set point for some time (hours), current tapers off.
    Float: Voltage is reduce to the Float set point where it is held against varying load (current) demands as long as possible.

    The SunSaver's set points are pretty much fixed: one choice for AGM's, a higher choice for FLA's. They may not be right for your particular batteries. Set it for flooded at 14.4.
    You can change the jumper wire on the MidNite meter to tell it the full charge Voltage should be 14.2 instead of 14.7 - it is looking for a minimum Voltage held for "so long" to tell it the batteries have received a full charge.

    As always, when you're dealing with inexpensive equipment some compromises are necessary. They just can't afford to build in unlimited selections when they're trying to keep the price down. Fully programmable charge controllers/battery monitors are hundreds of dollars.

    Don't try to use either of these with Trojan, Surrette, Interstate, or other 'higher Voltage' FLA batteries.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Re: Solar to run a fridge.
    The SunSaver's set points are pretty much fixed: one choice for AGM's, a higher choice for FLA's. They may not be right for your particular batteries. Set it for flooded at 14.4.
    You can change the jumper wire on the MidNite meter to tell it the full charge Voltage should be 14.2 instead of 14.7 - it is looking for a minimum Voltage held for "so long" to tell it the batteries have received a full charge.

    Don't try to use either of these with Trojan, Surrette, Interstate, or other 'higher Voltage' FLA batteries.


    I believe the maker of the batteries I am looking at getting is called "Crown". . .

    I would like to appologize for not reading all the posts completely. . . :blush: I was reading up on this thread last night, and noticed a few of my "silly" questions were already answered in previous answers. . . I know. . . these darn newbies. . :grr

    So, will it damage the batteries (or shorten their life) if they only get charged to 14.4 with the sunsaver and not 14.7 ?

    Thanks for all the help guys, I will keep you updated as I change things around. . . Still trying to pay for christmas :p
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.
    Skippy wrote: »
    So, will it damage the batteries (or shorten their life) if they only get charged to 14.4 with the sunsaver and not 14.7 ?

    This depends on the batteries used. As I mentioned, certain ones have rather high Voltage expectations. Not sure just what Crown recommends on theirs; check with your supplier (and make sure they check with the company, not just pull a number out of a hat). If you use too low of an Absorb Voltage you will not have full capacity and the batteries will not last as long as they otherwise might.
  • kellylippkellylipp Registered Users Posts: 21 ✭✭
    Re: Solar to run a fridge.

    I Googled Crown battery charging specifications and got a number of hits that directed me to good information. Get the model number off the battery and try that search. I found detailed charging profiles for a couple of different batteries...

    Kelly
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Re: Solar to run a fridge.

    I looked up "crowns" web site, and contacted them directly with the numbers . .. I will let you know what happens....
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • Ken MarshKen Marsh Solar Expert Posts: 114 ✭✭✭✭
    Re: Solar to run a fridge.

    Many thanks to Volvo Farmer for straightening us out on refrigerator door heat.
    I knew there was heat there but just assumed it was electric strip heaters.

    We have a combination two compressor Samsung.
    Are they the same way?
    If so which compressor supplies the door heat?
    Is the freon line supplying door heat directly off the compressor?
    In other words, is compressor superheat used to heat the door seal
    or is the door loop after the condenser where there is no superheat?

    Hope you are still watching this thread.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Re: Solar to run a fridge.
    Ken Marsh wrote: »
    We have a combination two compressor Samsung.
    Are they the same way?

    Since there are so many different makes and models out there, what I did was - an internet search on my specific brand and model. . . surprisingly, I found a complete diagram of where all the parts are and how its put together . . now I have a copy of it for the future when I have to fix it.

    Just a suggestion....
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • Volvo FarmerVolvo Farmer Solar Expert Posts: 209 ✭✭✭✭✭
    Re: Solar to run a fridge.
    Ken Marsh wrote: »
    Many thanks to Volvo Farmer for straightening us out on refrigerator door heat.
    I knew there was heat there but just assumed it was electric strip heaters.

    We have a combination two compressor Samsung.

    You have my deepest sympathies ;)
    Are they the same way?
    If so which compressor supplies the door heat?

    I have no idea. Unplug the start relay from one of them and see if you still get heat around the doors
    Is the freon line supplying door heat directly off the compressor?
    In other words, is compressor superheat used to heat the door seal
    or is the door loop after the condenser where there is no superheat?

    Again, I have no idea. These things aren't generally relavent from a repair perspective. Sorry I couldn't be more help.

    Hope you are still watching this thread.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Re: Solar to run a fridge.

    Well, I am still hanging in there. . . . I sent an email to the "Crown" battery guys, explaining my situation, and asking :

    If I go to your distributor and buy 4 of your 6 volt - 250 amp hour batterys, connected to make 12 Volts - will they have a nice a happy life if the sunsaver only charges them to 14.7 repeatedly - NOT including the occasional E.Q. charge....

    They sent me a PDF document, and asked me to check out page 3 for the answers.... Here is the pdf, what do you guys think ?

    Page 3 states an absorbtion charge of 14.5 for 12 Volt systems . . .
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    I don't think I'd worry much about 0.2 Volts on a flooded cell. Worst case would be higher water usage. Chances are pretty good that the Voltage set point is only accurate +/- 10% (1.5 Volts) anyway.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Re: Solar to run a fridge.

    Well, I am still hanging in there.

    Since we are getting into more sunny weather, I thought I would "test" the output of my panels. First I hooked up a 300 watt halogen light (actually uses 260 watt). Then I connected a 60 watt edison bulb. . . . and THEN I added a 12 V - 13 amp mini car heater - grand total of about 460 watts. Once the battery voltage dropped down to 12.23, it stayed there for 1/2 an hour. . . until the sun went behind a cloud . . .

    My question is :

    As the voltage drops, would the panels put out more power ? So if they are rated at 110 watts at 17 Volts, would they put out more at 12.23 Volts ? or would it still be 110 watts. . . just curious as the battery voltage stayed at 12.23 the whole time and did not change.

    Have not given up on adding parts, just taking my time before buying. . .;)
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Solar to run a fridge.

    Not quite.

    A panel's Wattage rating is based on Voltage at maximum power (Vmp) * current at maximum power (Imp). This is what they produce under "ideal" conditions.

    Since panels are current sources, they always try to supply maximum current (if under full illumination) but will allow their Voltage to drop below Vmp according to the load on them. Therefor you can have Imp @ 2 Volts or Imp @ 12 Volts or Imp @ Vmp, but the current output will not rise above Imp (except in cases of super-illumination or shorted output).

    So a panel rated for 110 Watts @ 17 Volts would have an Imp of about 6.5. If the Voltage is pulled down to 12 by the system it will still produce 6.5 Amps but @ 12 Volts or (6.5 * 12) 78 Watts.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Thank you very much BB . . I am planning on getting this whole solar thing up and running this year (new years resolution) keep ya updated !
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • scrubjaysnestscrubjaysnest Solar Expert Posts: 175 ✭✭✭
    Re: Solar to run a fridge.

    .................snip.................

    So a panel rated for 110 Watts @ 17 Volts would have an Imp of about 6.5. If the Voltage is pulled down to 12 by the system it will still produce 6.5 Amps but @ 12 Volts or (6.5 * 12) 78 Watts.
    We typically see this during the boost charging stage with our small system. Although the current runs closer to Isc then Imp at 12.5 to 13 volts.

  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Well guys, for good or bad, I finally managed too get some parts for this thing . . :)

    First, picked up the morningstar charge controller ...
    Attachment not found.

    Just recently, I picked up the 1,000 watt . . samlex inverter . . set up temporarily with the old batteries, and can run a 400 watt load for 1 hour.

    Attachment not found.

    Will let you guys know when I get the new batteries . . not good enough to run the fridge yet, but it does run my solar water heater pumps - no problems :)

    Attachment not found.
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Well guys . . I have been playing with my solar set up and here is what I have found out...

    1. I am running my solar water heater pumps 24/7 - the kill a watt meter is reading 1 KWH per day of usage. This one is always on the system.

    2. I am hungry - so I plug in my mini - forman grill - rated at 600 watts - too cook a hamburger. It takes 8 minutes too cook a burger. The solar pumps come on once in that time - drawing an additional 190 watts. . . no problems . . batteries drop down to bounce between 40 and 50 % . . . but by that time the pumps turn off , or the grill stops heating . . and the batteries go right back up . . .

    3 . I plugged in my washing machine too my samlex 1,000 watt inverter - surge capacity of 2,000 watts . . and it runs really slowly and hums . . Why ? I figured that it would either work for a short time (like the grill) but kill the batteries real quick - or overload the inverter.... it doesn't do either one . .. it just runs really slowly and hums - now after about 5 seconds of this, I pull the plug on my own - since it just does not sound health . . . :) What do you guys think ? If I get a good set of fully charged batteries and then try to run the washing machine - would it then overload the inverter - or run the washing machine at the proper speed ?

    4. Plugged in the fridge - works great ! But . . . since the batteries are not good enough to last all night long - I have not left the fridge plugged in 24/7 - but it does run it nicely ! I am trying not to pull the plug too much - switching back and forth - since every time I unplug it, and then plug it in -it goes into defrost mode . . hard on the fridge .. :(

    5 Stand alone a/c unit - draws about 700 watts continuous . . same thing as the washing machine - hums for a couple of seconds - then the a/c unit shuts itself off - inverter is fine - no overloads or warnings . . . so what do you guys think ? Proper batteries and it would run good or overload something ?

    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Well one more strange thing too report . .. I set my 1500 watt to 5 seconds, and plugged it in too the 1,000 watt inverter. . . it ran for 5 seconds at 950 watts . . what ??? II always thought that if it draws more than the inverter it overloaded the inverter . . can't be healthy for the microwave either . . :confused:

    I have also realized that the solar water heater is drawing 1 KWH a day, while the fridge only draws .65 or so . . . as well as the fact that I am not actually running the water heater now, I am saving alot more running the water heater than the fridge . . go figure . . 8)

    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Is the Inverter a TSW or MSW? That may be the source of the hum if that is all that is running...
    But I am thinking you are trying to max out the inverter...?? BUT you are forgetting the batteries are involved too, they too need to supply all the watts needed for ALL loads and stay above the minimum V the inverter needs...
    The rebound of the voltage after the load is removed is NORMAL... but you need to use the actual voltage at the lowest reading not % SoC for evaluation...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    westbranch wrote: »
    Is the Inverter a TSW or MSW? That may be the source of the hum if that is all that is running...

    Inverter is labeled as a true sine wave . . specifically purchased it for that reason . .
    But I am thinking you are trying to max out the inverter...?? BUT you are forgetting the batteries are involved too, they too need to supply all the watts needed for ALL loads and stay above the minimum V the inverter needs...

    Thats why I thought I would put this question in here, if it maxed out the inverter - it should overload right ? AND . . . your right. . . the batteries have too supply the power for the inverter . . my thinking is that if I had the right sized batteries with the capacity that I needed to run these things, it would also have the . . ummmph . . to overload the inverter . . follow that ? ?

    The rebound of the voltage after the load is removed is NORMAL... but you need to use the actual voltage at the lowest reading not % SoC for evaluation...

    Yes, seen a post in here recommending the craftsman clamp meter . . would that do the job needed ?

    oh ya, here is a pic of the inverter info . . . pst-1000-24

    Attachment not found.
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Skippy wrote: »
    Stand alone a/c unit - draws about 700 watts continuous . . same thing as the washing machine - hums for a couple of seconds - then the a/c unit shuts itself off - inverter is fine - no overloads or warnings . . . so what do you guys think ? Proper batteries and it would run good or overload something ?

    Get a good quality digital voltmeter and measure the input voltage at the inverter while this is happening. Also measure the voltage at the battery terminals while this is happening.

    If the voltage at the battery is OK and the voltage at the inverter is too low, then either your battery cables are too thin, too long, or you have a bad connection. If the voltage at the battery is also too low, it means the battery has too high an internal resistance.

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Well, I did a few more experiments on this set up.

    Plugged in my water pump - the one that pumps the water up from my 7 - 60 gallon rain barrels in the basement - with the meter attached - and it worked beautifully. for about 30 seconds.(full sun) Then the batteries were down too about 40 % and I unplugged it. Waited for the batteries too come back up too 100 % - about 30 seconds - then plugged it in again. With just those 2 runs, I am able too fill my washing machine for a large full load of laundry. So not only am I running my solar water heater full time, but I can fill my washer with rain water as well . . cool :)
    Small note here, while I was running the water pump at 900 watts - 9 amps - the solar water heater pumps came on ! I know they draw 189 watts, but not the amperage. The inverter still ran, but I had too cut it short - maybe about 20 seconds. That is in full sun as well ! The cooling fan works on the inverter.

    Woke up one morning, and thought - hey, lets leave the fridge plugged in and see.... works great ! runs the fridge and the solar water heater together, and once the fridge shuts off, the batteries still get put back up too 100 % - would not want too run them both overnight since the batteries have no capacity, but it does work ! :)

    So far so good, Thanks for all the help guys ! I will keep you updated.
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    Skippy wrote: »
    Well guys . . I have been playing with my solar set up and here is what I have found out...

    1. I am running my solar water heater pumps 24/7 - the kill a watt meter is reading 1 KWH per day of usage. This one is always on the system.

    Well guys, I will admit, that the numbers on the solar water heater might not be accurate, I had a look at the K.A.W. meter the other day, and after 48 hours it had used 1 kilowatt even. So that works out too about .5 of a kilowatt per 24 hours.

    2. I am hungry - so I plug in my mini - forman grill - rated at 600 watts - too cook a hamburger. It takes 8 minutes too cook a burger. The solar pumps come on once in that time - drawing an additional 190 watts. . . no problems . . batteries drop down to bounce between 40 and 50 % . . . but by that time the pumps turn off , or the grill stops heating . . and the batteries go right back up . . .

    The good news is, the grill works for pork chops too ! After 8 minutes, I have a solar cooked pork chop ! :) - Really drops the voltage in the battery bank, but it does work !

    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 308 ✭✭

    Ok.. guys.

    Have a price here for batteries and would like opinions  on them.

    Looking at getting 4 - 6 volt batteries. 232 amp hour at a 20 hour rate. F.L.A.

    Going to cost me 670$ not including tax or around 167 $ each.

    That would make me a 232 amp hour battery @ 24 V.

    That sound like a good match for my 3 110 watt panels ? . . . won't mind adding more solar either

    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Not a good match... 330 watts of panels is not enough for that size battery. 

    330 watts X 77% derate = 254 watts typical mid day performance

    254 watts ÷ 28.8 battery charging voltage = 8.8 amps charging current (assuming there are no daytime loads). 

    As a rule of thumb, most folks aim for a 10% charge rate... that would be 23.2 amps.  That may exceed the capacity of your controller.

     Depending on your loads and climate you may be able to get by with half of that.

    --vtMaps

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • BB.BB. Super Moderators, Administrators Posts: 30,192 admin
    Note 10% rate of charge is a good minimum for full time off grid (typical rule of thumb suggestion).

    However, if this is a "backup" or seasonal/weekend off grid system (i.e., sunny weather and/or +Genset when needed), it is possible 5%  solar panel rate of charge would work OK. (not disagreeing with vtMaps, just trying to clarify options).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    edited June 2016 #117

     I was concerned that I was underpowered. Guess I was right.

    What are the pros and cons to getting this battery bank ?  If I use 10 %  of the capacity then switch the fridge to the grid and let the batteries recharge would that work ?

    I would like to do more with this system eventually . . . i.e. washer once a week or so . . .  but I know that I can only use what I can put back in...

    So... if I add an extra 220 watt panel (300 $) with its own charge controller (300 $) I will still only have 14.7 amps of current. - It will charge them faster, but still way short of the 28 amp target.

    Wonder what would be a good combo for the extra amps I need ? The single panel/single controller is one idea ...

    Gotta do more readin ... :)

    Thank you for the feedback.

    Suggestions are welcome.


    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    edited June 2016 #118

    Well guys, I called the battery supplier today, and was forwarded to the "solar guy".

    After explaining my set up to him I asked him a few questions :

    1.  Can I use a 230 amp hour battery with my 330 watt - 8.8 amp panels. or do I HAVE  to have a smaller bank of batteries ?

    Answer : As a rule of thumb, solar installers try to use the 10 % rule  when figuring capacity vrs charging amps ( thanks for pointing that one out to me vtmaps ) - so a 230 amp battery would have 24 amps charging current.  There is nothing saying that I cannot have a 230 amp battery - charged by 8.8 amps -  as long as I don't drain them down so far that they will not receive a full charge within a week or 2 .  Constantly over using batteries and leaving them not fully charged will kill them quick.

    2. If I  do drain the batteries 10 %  (unplug the fridge) then leave them for 3 or 4 days for a recharge (which could happen in the middle of winter) would that harm the batteries ?

    Answer: No - no harm done.  As long as the batteries are recharged to full capacity within 2 weeks or so draining them down too 90 % capacity won't hurt. He quoted being able to use an 800 amp hour battery the same way, as long as you replace the amount taken out and recharge to full capacity - no harm done.  (thank you for clarifying the options BB )

    So, If nobody out there can say "don't get those batteries ! ! "   -  I am leaning towards getting this battery bank, and keeping an eye on the charge and discharge cycle very closely.... and hopefully before winter, getting a few more big honkin panels  :) .

    Which means, no more trying to run everything in the house, and then waiting for a recharge - like I have been doing with these outdated - overused AGM that I have here  . . . Once these things hit a certain % discharge, unplug the fridge and let them charge back up.  I will have to rewrap the fridge with that extra 2 inches of foam - making it 4 inches thick - so it only uses .65 of a Kw - and then go from there.

    Meanwhile, I will have to look into MORE POWER ! (insert evil laugh here).

    Thank you for the help and advice guys, its good to have some knowledge before and while talking to dealers - some of them really know their stuff - while others - not so much.

    Not going to pull the trigger for another 2 weeks on this one - more time for checking the forums :)   - keep ya updated as I go.


    Now . . .  where is the "how to care for lead acid batteries section" again ?  :):D



    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Skippy said:
    If I  do drain the batteries 10 %  (unplug the fridge) then leave them for 3 or 4 days for a recharge (which could happen in the middle of winter) would that harm the batteries ?
    Let's make sure of our terminology... are you talking about 10% SOC or 10% DOD?

    Skippy said:
    Answer: No - no harm done.  As long as the batteries are recharged to full capacity within 2 weeks or so draining them down too 90 % capacity won't hurt.
    Let's make sure of our terminology... does the "battery guy" mean 90% SOC or 90% DOD?

    You should never ever take a battery down to 10% SOC (= 90% DOD).   Generally the deeper the discharge, the faster sulfation sets in... the point being that if your batteries are at 90% SOC it doesn't matter if it takes a few days to recharge them.  When you start getting below 60-70% SOC you need to get them fully recharged as soon as possible. 

    Forklift batteries are routinely discharged to 20% SOC, but at the end of the shift they are recharged to 100% SOC with unlimited power and time (the grid). 

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
  • SkippySkippy Solar Expert Posts: 308 ✭✭
    The battery guy asked the same questions - in a couple of different ways - just too clarify what I was doing. :)
    So yes, I will be discharging the batteries 10 percent with 90 percent charge left in them and will be making sure that whatever power I take out of them will be returned in that one or two week period.  If it is not returned in that time, the load is disconnected until such time as the batteries ARE charged.
    Which will also give me incentive too add more panels - so I can do more. . .

    Thank you for pointing out that whole 10 % thing, never knew about that one. :)  Make sense if your going completely off grid.
    2 - 255W + 4 - 285W PV - Tristar 45 MPPT CC / 3 - 110W PV -wired for 36V- 24V Sunsaver MPPT CC / midnite bat. monitor.
    1 KW PSW inverter 24V / 2.5 KW MSW inverter-24V ~ 105 AHR battery.
    3 ton GSHP.- 100 gallon warm water storage / house heat - radiant floor / rad
    9 -220W PV - net meter - Enphase inverters and internet reporting system.
    420 Gallon rain water system for laundry.***  6" Rocket Mass Heater with 10' bed for workshop heat.
    Current project is drawing up plans for a below grade Hobbit / underground home.
  • vtmapsvtmaps Solar Expert Posts: 3,738 ✭✭✭✭
    Your plans to never let your battery get below 90% SOC may shorten its life.  Deep cycle batteries need to be cycled below 90% SOC or lead dioxide clumps will form on the positive plates.  (That's very different from an automotive starting battery that should always stay above 95% SOC). 

    Of course, when you cycle your battery deeper, you need more panels to get it back to 100% in a reasonable time.

    Deep cycle batteries are most cost effective when they are used... they are dying whether you use them or not.  You are thinking of getting 4 of those batteries and using only 10% of their capacity.  You could invest half as much (2 batteries) and use 20% of their capacity.  That would be more cost effective, and as a bonus your charge rate would improve (same panels, half as much battery).

    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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