Questions about the battery!

solarf.helensolarf.helen Registered Users Posts: 6
:-)I want off-grid battery but I am not sure about the brand that could have the best performance and warranty or something else. Also about the general price?

Thanks so much.



  • BB.BB. Super Moderators, Administrators Posts: 33,313 admin
    Re: Questions about the battery!


    First, solar power is expensive... In the US, solar power costs around $1-$2.00+ USD per kWhr.

    I don't know--but assume that in Beijing you pay around 0.61-1.00 RMB/kW-hr... Assume that exchange rate is 1 Yaun = $0.15 USD: That would be $0.10-$0.15 per kWhr (in USD)... Sounds pretty close to US power rates... So, Off-Grid solar would be around 10x the price of utility/grid power.

    So--the first thing you need to do is look at your loads and figure out how to reduce your power usage to the minimum needed (using efficient light bulbs, use efficient appliances, use a small laptop computer instead of a big desktop computer, insulate your ceiling / walls / windows, etc.).

    Next, you need to first identify your loads first (voltage, amperes, Watts, Watt*Hours).

    So, you may have small loads (small compact florescent lights, small fan, radio). Or you may have large loads that are not used very much (a well pump for home use). Or your loads may be large and go for a long time (well pump for irrigation of crops/food plants).

    Once you know your loads (peak Watts, and Watt*Hours) -- you need to size your battery bank. A good rule of thumb is to design the battery to supply your daily load for 3 days, and to only discharge the battery to 50% state of charge (for long life--if you use all of the battery's capacity--run it dead--it will not last more than a few weeks or months). So, 6x your daily energy use for battery bank size.

    Then you need to figure out how many solar panels you need.

    Where are you (number of hour of sun per day--including effects of weather), your seasonal needs (more power in summer, less in winter?). Will you need a generator to charge the batteries during cloudy weather, etc...

    In the end, you will find that a solar system is not cheap. In the US, an off-grid system will be around $10-$20 per Watt (if you need 1,000 watts of solar panels, ~$10,000 worth of parts).

    Your costs will be different (solar panels may be less expensive), good quality charge controllers may cost more, etc.

    There is no one good answer we can give you with zero information from you...

    If you want to see what good quality equipment/parts cost in the US--you can visit our host's webstore at:

    Obviously, shipping to China (or where ever you are) from the US is going to have its own costs/issues. And, for many/most of your needs, you would be better off sourcing locally.


    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Questions about the battery!

    i don't know about the quality, but it would be cheaper i would think for you to buy a battery more local to you. the warranty may give you a clue except when dealing with agm types.
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