Nine dc-to-dc converters (three each of buck, boost, and buck–boost) that offer continuous input current, suitable for renewable energy maximum power point tracking, and continuous output current applicable to module parallel connection, have been presented. Theory and simulations established which topologies offered the lowest input ripple current for each of the three transfer functions (buck, boost, and buck–boost). Practical results substantiated both the theory and simulations. The buck converter D6, offers a low input ripple current, since the input inductor experiences only modest impressed voltages. The best boost converter, D3, in terms of low input current ripple, utilizes the two circuit inductors effectively in series.