I am designing a complete solar-powered backup...

I am designing a complete solar-powered backup system for a 3-bedroom villa with an average daily consumption of 35 kWh. I need expert advice on the following: 1. SOLAR PANEL SIZING: Using LONGi Hi-MO 5 panels (545W each, 21.3% efficiency, Voc = 49.6V), how many panels do I need to cover 35 kWh/day assuming 5.5 peak sun hours? Please confirm if 14 panels (7,630W total) is sufficient after accounting for system losses (~20%). 2. INVERTER SELECTION: Which is better for this application - the Growatt SPF 5000ES hybrid inverter or the SMA Sunny Boy 5.0? The Growatt SPF 5000ES supports off-grid and grid-tie with battery backup, while the SMA Sunny Boy 5.0 is primarily a grid-tie inverter. Given that I need a backup function, which do you recommend and why? 3. BATTERY BANK CAPACITY: I am comparing two options for a 48V LiFePO4 battery system: Option A: 4x Pylontech US3000C (3.55 kWh each) in parallel = 14.2 kWh total at 48V Option B: 2x BYD Premium HVS 5.1 kWh modules in series = 10.2 kWh at higher voltage Which option provides better performance, depth of discharge, cycle life, and value for this villa application? 4. MPPT CHARGE CONTROLLER SIZING: For a string of 8 LONGi Hi-MO 5 panels: - Total Pmax = 8 x 545W = 4,360W - String Voc_max = 8 x 49.6V = 396.8V What MPPT charge controller specifications (voltage range, current rating) do I need? Is 396.8V within safe limits for standard MPPT controllers? 5. NET METERING / GRID FEED-IN: Can this system legally feed excess solar generation back to the grid under Saudi Arabia's ECRA (Electricity & Cogeneration Regulatory Authority) net metering regulation that became effective on 2026-01-01? What are the technical and administrative requirements for grid connection approval? Note: Our installation bid review is scheduled for 2026-08-15, so I need this information urgently to finalize the system design and evaluate contractor proposals.