Methods and circuits for distributing power to suspended-particle-device (SPD) film products including SPD windows, SPD shades, and other SPD products, which are referred to generally as SPD loads. A driving voltage derived from a primary power source is provided to an SPD load by backbone wiring which carries a low AC or DC voltage derived from the primary power source, and a conversion stage which converts the low voltage to an AC driving voltage which is then supplied to the SPD load.