If you want to connect the solar panels in series, you will just need EF Solar Charging Cable (MC4 to XT60 Solar Cable) which comes with the power station when you purchase it. But if you wish to connect them in parallel, then you will need to purchase Solar MC4 Parallel Connection Cable (which you can find on our official website).
Also we do not recommend that you only use 2 sets of EF 110W solar panels to charge DELTA Max, as it will take a very long time for it to charge. We suggest you use minimum 3 sets of EF 110W solar panels, or 2 sets of EF 160W solar panels.
Please keep in mind that the recommendations made above are applicable for EF solar panels. If you are using a third party solar panel, then make sure the specification of the solar panel meets the requirement of the power station and the connector of the solar panel is MC4 type. Also note that our products already have an MPPT board inside that controls solar charge, so if the third party solar panel has a separate controller, it might affect the solar charge.
Hope this was helpful :)