Lithium Iron Phosphate batteries

I am using Lithium Iron Phosphate 3.7volt cell @ 4700mA.hour rating. I want to make batteries with output voltages of 24volts and 32volts. They will be recharged from photovoltaic panels only. 7 LiFePo4 cells = 25.4volts and 9 LiFePo4 cells = 33.3volts. Four 12volt photovoltaics are connected in series. The maximum power point voltage is approximately 50 volts. What family of integrated circuits( or design) will individually charge and manage the cells in the batteries while they supply intermittant loads of 7watts and 18watts respectively?

The 7 cell battery will need a DC to DC converter to give a stable 24volt with peaking current of 1amp and the 9 cell battery will need a DC to DC converter with a stable 32volts and a peaking current of 1.5 amps. What DC to DC chip sets ( or design ) can I us?

Advice from anyone will be welcome.