[Johnythree]

> Solar cells' output varies greatly, hence it needs to be DC/DC converted to a fix voltage to be of any use.

This is simply wrong. It is true that modern MPPT solar regulators use PWM to extract the maximum power, but for years, a simple on/off regulator was used to prevent overcharging.

The reality is that a solar panel is essentially a "Constant Current" supply, so the panel puts out the same current over a wide range of battery voltages. It is the battery which puts out a Constant Voltage at whatever current the load requires.