This paper presents our recent results on the high-rate deposition of high-efficiency and highly stable hydrogenated amorphous silicon (a-Si:H) solar cells with all layers deposited by 13.56 MHz radio frequency glow discharge. Using a linear disilane (Si2H6) grading process, high initial active-area efficiency of 11.42% has been obtained for the a-Si:H top cells with an effective i-layer deposition rate of 8 Å/s. It is also found that the light-soaking stability of the a-Si:H top cells is much improved by the Si2H6 grading process with the best a-Si:H top cell exhibiting only 11.2% light-induced degradation after 1000 h of light-soaking. Integrating the high-rate deposited a-Si:H top cell in an amorphous silicon/amorphous silicon germanium (a-Si:H/a-SiGe:H) tandem cell, an initial active-area efficiency of 12.57% is achieved. After light soaking for 1008 h, the stable efficiency is still as high as 11.02%, corresponding to only a 12.31% degradation. To the best of our knowledge, this is the best performance for a-Si:H based solar cells at such a high deposition rate by 13.56 MHz RF-PECVD. Possible mechanisms responsible for the superior stability of the a-Si:H solar cells deposited by the Si2H6 grading process are discussed.