Can I use capasitors instead of batteries for off grid solar?

robert1701 Registered Users Posts: 12 ✭✭
I saw these 12V 500F capacitors. Could I use these instead of a battery to store solar electricity for off grid use?


  • BB.
    BB. Super Moderators, Administrators Posts: 33,412 admin
    The short answer is probably not....

    The actual energy storage is a bit more complex... Need to know the Min/Max capacitor voltage, the x,xxx Farad rating, and use the equation:
    • 1/2 * x,xxx, Farad * (Vmax^2 - Vmin^2)
    • example: 1/2 * 500F * (14.5v^2 - 10.5^2) = 50,000 Watt*Seconds
    • 18,000,000 WS / 3,600 seconds per hour = 13.9 WH
    • 13.9 WH / 12 volt nominal = 1.2 AH @ 12 volt battery equivalent
    There are lots of issues with using "super caps"... Partly is they are very sensitive to voltage, and they also tend to have relatively short lives (less than 5 years?).

    If you only need that small amount of stored energy (compared to 2x 6 volt @ 200 AH "golf cart" batteries in series making a 12 volt @ 200 AH for around $200)--It could work... But you really need to know your energy needs. And it is hard to beat Lead Acid and Li Ion batteries (and other chemistry types).

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