Re: how many mounting rails behind each panel?
??? running the supports perpendicular to the long side would give more support to the panel. doing the other direction would leave the long side with NO support for the max length per panel except at each end..??? the latter to me is a recipe for failure.
100% Off Grid @ 51* 46' N lat 124* 44' W long
New House system: MX-60 w RTS, 2 - 120 W 12v PVs, 2 - C&D AT-15P AGM 24V 950Ah, Cotek ST1500W inverter, TBS 30a-24v Omni-charger, Honda Eu3000is, CL 150 coming out of a box, coming - 2 arrays @ 2240W
Guest cabin system: 3 - 70W panels to SB 2000e CC, with 2 - 100 ah 12v SAFT wet NiCd's , 600W TSW Inverter
Mothballed :Absolyte AGM 1055 Ah 12 v battery, XBM w/ Palm Vx data recorder, 3500 W Mitsubishi genset, TC40 (12V) charger ...