What is the minimum operating voltage for your solenoid in this application? Vmin = ?
ec=it If you discharge a capacitor with a constant current (a good first-order approximation for just about anything), the change in voltage times the capacitance equals the constant current times the discharge time. Rearranging:
c = it/e If Vmin is, say, 20 V, then 1A x 1 second divided by 4 V = 0.25 F. So, 250,000 uF will get you 1 second of total operating time. Scale up or down from there.
ak