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The storage battery bank size theory is for a minimum effective safe domestic size with 2 adults 2.4 children, 2 cooking session of 1/2 an hour are available to no more than 15% DOD at constant current 8Kw(more a technical point). Note: remember all cooking should be done using float charge input method.
- meaning "8Kwh to 15% DOD" = minimum 4200ah total of "12v amp value" battery bank.
Batteries deteriorate capacity over time so if the 4200ah scenario is suitable in theory, in practice it should be around 5000ah minimum.
Incidentally, the previous would be an 8Kw(generators) hybrid power system although the same with downsizing can be a 6Kw(generators) hybrid(bu'! the wind turbine MUST be placed 15 meters up minimum not any lower!).
Battery Bank size for 12 years as 6000ah-12v-value is based on all "large jobs(washing machine, cookers, air-conditioner, heater, hot-water)" always having solar generation input during their operation with panel system of Pmax-3Kw and a 3Kw wind turbine too with all house large components downsized for max. 2Kw current draw (although if you do not use an air conditioner beyond 1Kw-electric input you do not need much downsize except the washing machine) .e.g. 1500w hot-water element , or 2000w portable grill oven, 2000w accessory hot plate, 2000w(electric-input) air conditioner[a portable air ice is best they are only 1000w and a giant 700L 2 door refrigerator is not an actual big item, they switch on for 5 minutes every 1/2 hour but worth 2Kwh-in 24hrs(2x however, scrapes large)] (no more than 3Kw constant current draw "normally/usually" at any one time. From 100% to 85% full (15% DOD) with no solar or wind input at 3Kw current draw takes 3 and a half hours - and that is a single days maximum discharge allowed making 6 hours of 3Kw constant current draw if solar and wind are present)! If any one other large item is switched on then one that is presently operating should be switched off!
For normal house appliances and no more than 3Kw(electric-input) air conditioner the generator needs to be 5K-solar and 3Kw rated wind turbine minimum (but no more than 5Kw current draw "normally/usually" at any one time - after dark, air-cond. should be on low or half).
(*)The above is because the 15% DOD maimum discharge theoretical marker is a safety point reserved for mid winter and mid summer.
For anyone using twelve volt power system to live in one room, here is what can make a 2000ah battery bank in 2v pieces of reasonable quality. 12v requires good 2v deep cycle batteries for partial cycling on that one day of the year you wash.
See (*)The proper tactic of using it (12v page but same as any size w or Kw system)
The average all exclusively electrical energy supplied house in Australia is between 25Kwh to 35Kwh daily,
hence draw at "1Kw"(the select options field) down to 15% DOD should "hypothetically(not necessarily)" equal "at least" around "25 hours" in the decimal-fraction hour field(output answer) in the following form, relating the settings of AH(ampere hours) of battery bank filled into the "battery banks TOTAL 12v worth of AH's" and selection of "@ "X"Kw current draw" selector.
If you had e.g. 12 x 3000ah "2"volt(not 12) batteries, then 6 batteries in series makes 3000ah of 12 volts, so 12 batteries = 2-lines x 3000ah = 6000ah TOTAL @ 12 volts.
When batteries are added inline in series the volts are added together and raised, but the AH remain the same.
When batteries are put in parallel, tha AH's are raised but the volts remain the same.
For the storage quantity by 12 volt batteries the total storage is easiest by 12v.
If you have 80 of 12v batteries that are 80ah batteries that makes 6400ah. So if all the 80 were parallel(never do that) the calculator will say you have at "1"Kw , "11.566265060240963" hours = 11.566265060240963 Kw/h's.
By the same point, if our 80ah 12 volt batteries were arranged like next, "8 lines of" --- "10 batteries in series" using 120v power system storage ,
and we used a calculation for 120v at current(ampere) draw of 1Kw it would be exactly the same!!! "11.566265060240963" hours = 11.566265060240963 Kw/h's. !!!
So you can build any voltage system you want "with 12 volt deep cycle accumulators" but voltage(by battery arrangement) does not and cannot change the quantity of electricity stored!
Just add all the 12v batteries AH ratings together for the total(equivalent to multiplying the AH rating by the number of batteries) , or if you have 2v single cell deep cycle accumulators(batteries), divide by six the total number of batteries and then multiply that number of accumulators by the AH rating they have(they should all be the same! e.g. 3000ah or 250ah or 80ah ... whatever e.t.c ...)
For an actual permanent off grid system, because "14000ah worth of 12v (25Kwh's-15%DOD)" size is too costly(for dedicated 10+ years), and as much the power system can use by management 1:1 ratio(half battery supply AND half wind/sun generator) of "battery bank" to "direct sun/wind generation" can be the day/night efficiency balance when added together, only 6000ah worth of 12v for normal grid mimic is required and around 4000ah for smaller systems the house has had its appliances remodeled for efficiency.
Hours of 240v usage from Lead Acid(Gel/fluid) battery bank storage of 12v Ampere Hours total (By DOD float discharge)
@ "X"Kw current draw [REQUIRED]
Battery Bank in 12v AH Total [REQUIRED - numerals only]
|(5 years Max) Kw/Hours of 240v To (30% DOD -hours) (Total in Minutes )|
|(10+ years) Kw/Hours of 240v To (15% DOD -hours) (Total in Minutes )|
Calculate The number of Discharges(at whatever DOD - we're using 10% - 15% in this off grid model for 12 - 15 years) as days into years (approx 1 discharge is one day).
Number of Discharges to X% DOD discharges to Years
Calculate the "single battery AH size" and the "total quantity of batteries(accumulators)" required for the Battery Bank at System voltage (and "number of series lines" and "accumulators p/line")
[Warning! General rule of thumb: Never use a battery below 80ah unless the total generator is "below 6Kw" and or below 96 volt (note: 65ah -to- 80ah is just ok up to 8Kw and 240v) , never use an accumulator below 40ah unless the total generator is "below 3Kw"]
NOTE: The AH for each battery is the approximate size only, an actual product will have its manufacturers closest size. This is a rough guide only.
[ (Desired(aberration) single-unit Battery AH size) ] [ (Power System Battery Bank Voltage) ] Total Battery-Bank AH (as 12v)
[ Total number of 12v accumulators ] [ number of system voltage accumulator Lines (12v accumulators per Line ) ] [AH of each 12v accumulator ]
WARNING - BATTERIES IN PARALLEL ARE ONLY ALLOWED 3/4'RS THE NUMBER OF LINES(PARALLEL) TO THE TOTAL NUMBER OF "CELLS" LINKED IN SERIES TO OBTAIN THE VOLTAGE !!!
There are many chemical combination types of lead acid battery system, relating "Lifespan In Years" because of temperature and chemistry type!!!
* PAM additive long life lead acid. Link: PAM additive deep cycle
* GEL more efficient basic lead acid or with PAM.
* Light constructed short life low discharge quantity low temperature operation.
* Longer life-span high temperature, heavy construction. Link: Quality GEL lead acid
* AGM Absorbed Glass Mat.
* Silicon Lead Acid wide temperature operation range.
These are the common Lead Acid deep cycle types and efficiency varies immensely with ,
* price (above or below MOQ , company and set quantity) * Note, always buy "EXW" or "CIF"(particularly) only!!! (*sp-note: MOQ - Minimum Order Quantity - e.g. units: "sets" or "pieces")
* DOD depth of discharge ratings (shorter float life-span 15%DOD is similar to 30%DOD - long-life 15% is more double 30%)
* with temperature-float-lifespan (accumulator model life-span should be more than 10 years always at or above 20o Celsius!)
* local environment temperature affected "ah capacity".
* current draw "rate of discharge" affected "ah capacity".
In short, there can be any combination of mentioned above offered , but it is a matter of verifying the price , the model and "data sheet information" are effective at a 12 year job.
You need to be sure it will operate around 50% capacity at 10oC , the float life is more than 12 years at 20oC minimum , and discharge to 30% is at least 1600 discharges , and if a GEL.
In short always ask for an estimate of 15% DOD and 30% DOD and the data sheet, and it always requires a high quality "Lead Acid" to be economic enough.
*As explained later, there are ways of keeping the temperature of batteries at a level that will give more than 10 years float life and around 80-90% capacity to charge to.
RECAP NOTE: Remember as said before, only use a totally sealed battery type, NEVER ventilated to atmosphere!