A lot of folks have a misperception of 'voltage' of a PV panel.
You can take a panel that has an open circuit voltage of 22 vdc and charge a 3.7 v battery or charge a 15v battery with it, as long as its peak illumination current doesn't exceed battery max charge current rate.
The simplest model for a silicon solar cell is an illumination based current source that is voltage clamped with a parallel diode. When no external load is applied to cell, all the illumination generated current just goes down the inherent diode of the cell creating an open circuit voltage of the diode drop.
You must understand the temp characteristic of a diode to understand why a certain number of cells are hooked in series for a given target battery voltage.
It is desireable, but not absolutely necessary, to pull the illumination current off at the maximum voltage possible, which is just as the inherent diodes barely starts to conduct. This gives the maximum power from the cell. At 25 deg C, the unloaded voltage across the diode when all the cell's current is passed into it is about 0.65 vdc. This is well into diode conduction so the maximum power loading where about 3% of the illumation current goes down the inherent diode is just slightly over 0.5 vdc per cell.
Now if you know what happens to a silicon diode forward voltage drop over temp you understand the margin that must be put into the number of cells stacked to ensure the PV panel's net useful voltage stays above maximum required charger battery voltage. In full sun, in the heat of summer, with significant cell heating, the diode conduction voltage can be less then 0.5 vdc yielding a max power point on cell of about 0.4 vdc. When it is cold, the effect is opposite and you may end up with a cell max power point of over 0.7vdc.
Typical PV panel to charge a 12v lead acid, which requires a 13.2vdc float voltage and 14.4vdc bulk voltage, is typically 36 cells in series. This also happens to be about the same requirement for four A123 cells in series.
You always need a charge controller to prevent overcharging and current backflow when dark. The simplest PV charge controller, known a PWM controller, just has a series switch that opens the connection to the panel when the max battery charge voltage is reached. It then just duty cycles to maintain the average desired charge voltage on the battery. Remember the panel is acting as an illumination based current source.
You can also make a charge controller with a shunt regulator but it must be able to dissipate all the power the PV panel produces. In your four A123 cells this would be a shunt regulator of 14.6 vdc.
You also don't want a cell size that produces a current at full sun that exceeds the max charge current of the battery being charged. A good quality cell produces about 35 mA per sq. cm. area at full sun intensity.