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 guidance on the following specific technical points: 1. SOLAR PANEL SIZING: Using LONGi Hi-MO 5 monocrystalline panels (545W each, 21.3% efficiency), how many panels do I need to cover 35 kWh/day assuming an average of 5.5 peak sun hours in Saudi Arabia? Please confirm the total array wattage and layout recommendation. 2. INVERTER SELECTION: I am comparing two options: - Growatt SPF 5000ES (5kW hybrid inverter with built-in MPPT, supports off-grid and on-grid with battery backup) - SMA Sunny Boy 5.0 (5kW grid-tie inverter, no built-in battery support) Which is more suitable for a hybrid system with battery backup and potential grid feed-in? What are the key differences in terms of efficiency, battery compatibility, and scalability? 3. BATTERY BANK COMPARISON: Option A: 48V system using 4x Pylontech US3000C modules (3.55 kWh each, LiFePO4) connected in parallel = 14.2 kWh total usable capacity Option B: 2x BYD Premium HVS 5.1 kWh modules connected in series = 10.2 kWh at higher voltage (HV system) Which battery configuration offers better performance, safety, cycle life, and value for a 35 kWh/day consumption villa? 4. MPPT CHARGE CONTROLLER SIZING: For a string of 8 x LONGi Hi-MO 5 panels: - Total Pmax = 8 x 545W = 4,360W - Voc per panel = 49.6V, String Voc = 49.6V x 8 = 396.8V What MPPT charge controller specifications are required to handle this string safely? 5. SAUDI ARABIA NET METERING (ECRA): Under Saudi Arabia's ECRA net metering regulation effective 2026-01-01, can residential solar system owners legally feed excess solar generation back to the Saudi Electricity Company (SEC) grid? What are the application requirements and maximum allowed export capacity? 6. INSTALLATION BID REVIEW: My installation contractor bid review is scheduled for 2026-08-15. What key technical clauses and quality standards (IEC, IEEE, or Saudi SBC codes) should I insist on including in the installation contract? Please provide detailed technical answers to each point above.