you just need to maintain 16 volts minimum to 60 volts maximum input. Assuming your single panel will output 16+ volts you should be fine single. If you have great sun with no chance of shading any portion of both panels, series connections will work best. If any of the two panels receive shading, both panels will be affected when connected in series however.
With Parallel you have a maximum of 12 amps input which will be right at the limit if you connect two of your panels in Parallel. You should be less affected by partial panel shading when connected in parallel.
Basically my advice is go with series for simplicity and the ability to add even another panel to the mix in the future assuming you have excellent exposure to the sun with no shading. If you are only going to have two total panels as you described and have any chance of partial shading I would go with Parallel.