perfect and efective way

alkhaleejsolar
alkhaleejsolar Registered Users Posts: 11
hi,,i have 2 solars 18 volt 150 watt

12 volt inverter 800 watt , with 12 volt 200 amp battery

plz give me correct way,to charge this battery

for this ,panel will be wired in parrel ,or in series

and which way is perfect ,series,or parel,
if the battery have 30 persent backup
,
how many time will take,to full the battery,,


sun 8 hours on panels,,

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: perfect and efective way
    hi,,i have 2 solars 18 volt 150 watt

    Good... Assuming that is Vmp is ~17.5-18.6 volts or so--That is perfect for a PWM (Pulse Width Modulated) solar charge controller on a "12 volt" battery bank. A PWM controller is (more or less) simply a switch that turns on when charging is needed. And turns off when no charging is needed. The on/off period can range from seconds to fractions of second--depends on model of controller and other stuff.

    A MPPT charge controller can take Vmp (for a 12 volt battery bank) from 17.5 volts to around 50-150 volts or more (depending on brand and model of MPPT charge controller--MPPT Maximum Power Point Tracking). The higher the voltage/current ratings, the more expensive controller ($100 or so PWM controller vs a $300-$600 or so MPPT controller).

    MPPT solar charge controllers are buck mode switching power supplies (typically). They use transistors and inductors to "efficiently" down convert from High Voltage/Low Current of the solar array to Low Voltage/High current used by the battery bank for charging.

    If you are familiar with a Variable Transformer (Variac) used for AC--You can input 230 VAC and provide from 0 to 230 VAC (or more) in variable voltage output (used for theater lighting and such--in the olden days). An MPPT solar charge controller is (sort of) the DC version of a variable output transformer.

    This allows you to, for example, use a "high voltage" solar array (put your two solar panels in series) and send the energy a longer distance over thinner copper wire (save money on copper wire from solar array to battery shed).
    12 volt inverter 800 watt , with 12 volt 200 amp battery

    What kind of battery are you using? A "car" or "truck" battery? A sealed/AGM/GEL battery? A Marine Battery? A deep cycle battery?

    Each battery has its own requirements for long life (how much current, how many hours at XX amps, etc.)... For a standard deep cycle battery, you can draw C/8 (AH/8 hours) for a good life:
    • 200 AH * 1/8 hours = 25 amps for 8 hours until dead

    For an inverter, that would typically be around:
    • 25 amps * 12 volt battery bank * 0.85 inverter efficiency = 300 watts average AC output

    Note--Made some simplifications here--the 200 AH battery capacity is typically done at C/20 hour rate... Discharging at C/8 rate will make the battery appear to be somewhat "smaller" in capacity.

    Also inverters may have better than 85% efficiency or worse than 85% efficiency--You have to check your operating loads and inverter manual for details (we try to error on the "conservative side here".

    Also, for long battery life with a typical "deep cycle" battery, we try not to drain more than 50% of the battery's capacity... The deeper the cycling, the shorter life the battery will typically have. Also, you want to "quickly" recharge your battery bank too (the more days/weeks/months a lead acid battery spends "discharged" the faster it "sulfates" and loses capacity).
    plz give me correct way,to charge this battery

    Normally a good charge rate for a lead acid battery is around 5% to 13% rate of charge for solar panels. You can go as high as 25% rate of charge (or even higher for AGM), but it is usually not cost effective for solar (plus there are some "other issues" about possible over heating of the battery bank if deeply discharged and very quickly charged).

    So, for a 12 volt @ 200 AH battery bank, the typical solar array size would be:
    • 14.5 volts charging * 200 AH * 1/0.77 panel+charger deratings * 0.05 rate of charge = 145 watts minimum
    • 14.5 volts charging * 200 AH * 1/0.77 panel+charger deratings * 0.10 rate of charge = 290 watts healthy nominal
    • 14.5 volts charging * 200 AH * 1/0.77 panel+charger deratings * 0.13 rate of charge = 377 watts "cost effective maximum"

    For your 300 watts of solar panels--They match very nicely with a 200 AH @ 12 volt deep cycle battery bank.
    for this ,panel will be  wired in parallel ,or in series
    

    For a PWM charge controller, you would wire the panels in parallel (with fairly heavy wire from the array to the charge controller).

    With a MPPT charge controller (more expensive, a bit more difficult to find "good MPPT controllers" from Asia) you can wire the two panels in parallel (just like PWM).

    Or you can wire the two panels in series with MPPT--provided the maximum input voltage is over ~50 volts or so (Voc-cold.... The voltage open circuit of the solar array in very cold weather cannot exceed the charge controller's maximum input voltage rating). Solar panel Voc/Vmp rise as the temperature falls (particularly below freezing).
    and which way is perfect ,series,or parallel,

    If doing it for the least amount of money and the solar array is "close" to your battery bank--Then in parallel with a PWM controller is probably the best answer.

    If you have "extra money" and can buy a "good" MPPT charge controller rated for your needs and you have a "long distance" from the array to the battery bank, then putting the two panels in series with an MPPT controller will probably be a better solution.

    Note, if you want to add more solar panels later, in parallel, you can add one panel at a time (assuming Vmp matches). With two panels in series, you have to add two panels at a time.
    if the battery have 30 persent backup, how many time will take,to full the battery, sun 8 hours on panels,,

    Roughly, assuming you are using 30% of your 200 AH battery bank (using 60 AH or discharging down to 70% state of charge) and you have 5 hours of "good noon time sun per day", very roughly:
    • 60 AH * 14.5 volts charging * 1/300 watt of panels * 1/0.77 derating = 3.77 hours of noon time sun

    Now, in reality, when the sun rises, you don't get "300 watts" from the solar array, so starting current is less. Second, batteries will take "full" charging current up to around 80-90% state of charge--Past that point, the controller will hold ~14.5 volts and the battery will accept less and less current--probably around 2-4 hours of additional charging time.

    So--more or less, it will take much of the day to "fully" recharge your battery bank from a 30% usage. Obviously, cloudy weather/less sun in winter (depending on how close to the equator you are) will affect how quickly your battery bank will charge... Some people, once the battery is mostly charged can start adding loads in the after noon for other needs while the battery is drawing less than 100% current from the array--Radio, computer charging, water pumping, etc.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • alkhaleejsolar
    alkhaleejsolar Registered Users Posts: 11
    Re: perfect and efective way

    really ,a nice reply ,,thanks,,sir,,

    i have at the moment ,pwm,charge controller,

    ok,now i will wired panels according yr advice, i have acid battery ,truck battery,

    one thing sir,plz,,i want to ask,,

    if some one don,t have any charge controller
    ,can his solars will charge the battery ,
    as i know ,will charge battery ,but ,may be over charge,may be damage battery..becoz ,charge controller is only for safety of battery ,overcharge,,,,or charge controller is must,,plz explain, becoz here are many people ,using solar panels with out any charge controller,,so plz inform,that with out charge controller also will charge ,??//

    thanks,,sir ,,
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: perfect and efective way

    You are very welcome...

    A battery charge controller only "stops" charging once it has determined that the battery is "fully charged". So a solar panel connected directly to a battery bank will "charge" the battery--The risk is over charging eventually damaging the battery's long term health.

    Basically, a lead acid battery is a little chemical factory. You have the reversible effects--as the battery discharges and recharges. And you have the irreversible effects (besides aging). Here, once the battery is fully charged, it now "gases"... Or electrolysis--conversion of water into hydrogen and oxygen gases (and heat too).

    For sealed batteries (AGM, GEL, etc.), to much gassing (making hydrogen and oxygen gases) can over heat the catalyst (some sort of "noble" metal that recombines the hydrogen and oxygen back into water--and heat) or even overpressure the battery and cause it to "vent" (release gases and spray out some electrolyte--both which will cause early life failure for the battery bank).

    For flooded cell lead acid batteries--You can just add distilled water--so they tend to be a bit less likely to be damaged by over charging. However, the extra heat and gassing is hard on a battery bank (can cause plates to flake off material, cause positive grid to corrode due to oxygen gas forming on the positive plate, etc.).

    So, these effects are usually something that causes damage over time... Your battery will not fail if you over charge it once... And if you over charger several times a week, you may cut a few years off the battery life (or perhaps not--depends on how much over charging we are talking about).

    More or less, using the Battery AH capacity, and a rate of charge (i.e. 1% rate of charge for a 200 AH battery bank would be 2 amps):
    • 1% rate of charge or less--Float charing. Keep the battery charged in storage--You may not need a battery charge controller
    • 5% rate of charge--About the minimum rate of charge needed to keep a deep cycle battery happy (and to recharge a battery that has some cycling).
    • 13% rate of charge--About the maximum rate of charge for most flooded cell batteries without thermal management (i.e., deeply cycled batteries like those in an electric fork lift may need active cooling fans and/or remote battery temperature sensors to prevent thermal run away--Hot batteries need lower charging voltage--A charge controller that does not measure battery temperature may supply too much charging voltage/current, causing battery to overheat even more...).
    • 25% rate of charge--The maximum charging current you probably should ever recharge a lead acid battery. Cause heat damage to plates, over heat battery, etc.

    So, the larger the solar array, the greater chance that a battery could be damaged from over charging--Of course, we have not talked about loads at all yet. If there are enough loads to keep the battery from getting too much charging (say daily use for pumps water, lights, fans, etc.)--Then the battery will spend less time "bubbling" from over charging.

    A battery that was not being recharged correctly could fail in weeks, months or a year or two... The same battery with proper charging (and prevented from over discharging) can last 3-8 years or more (depends on quality of battery, type of battery, how it is discharged/recharged, operating temperature, etc.).

    If you are using truck/automotive batteries--They may only last a few years anyway if cycled deeper than 10% or 20% (they are usually designed to supply short bursts of high current to start the engines, not to be deeply cycled for hours on end).

    Remember, batteries only "die" when they no longer store enough energy for the customer's needs. If the loads are small (relative to battery capacity) and/or much of the use is during daylight--Then a battery could be "failed" (loss of 20% of capacity), but still work very well for the end user's needs for a long while to come.

    Here are a couple of Battery FAQs--Sorry, I only have links in English--Hope they will help you (lots of boring/technical reading in a foreign language--oh the fun ;)):

    Battery FAQ
    www.batteryfaq.org

    And you can call me "Bill"--That is my real name.

    Sincerely,
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset