Using small solar panels together, worth it?
If you need more current, then wire them in parallel (which will give you double the current of one cell). Putting two in series will give you double the voltage of one cell. 

A regulator can be used, but the problem with this approach is it will not run the solar cells at greatest efficiency. To run the cells at greatest efficiency an MPPT tracking circuit will be needed. 

One thing that might work is a buck DC DC converter.

If you're charging a battery, then a controller to monitor the charging will also be needed. Here are a few examples, make sure you match the input cell current and voltage within the chargers range.