New PV system, single or dual string?

[Billy sheds]

Hi, I'm having a PV system fitted to the flat (inclined at 15 degrees) roof of my garage. I was under the impression, from earlier chats, that it was to be fitted in two strings. The spark installing the system electrics said it's a single string. The quotation just lists 10 panels (Trinasolar vertex S 390W), 1 sofar solar 3000TL-G3 inverter, 1 emlite ECA2 single phase KWH meter, then "All hardware".... Should I be asking for 2 strings?
Many thanks, Bill

 

[binky]

it's a single MPPT so single string.