A 12 volt panel has maximum power at around 17 volts so will need a minimum of 2 in series in a 24 volt system. There is no technical disadvantage but larger domestic sized 24 volt panels are cost effective.
[PDF Version]
A typical 400-watt solar panel is 79. If you have a 1000 sq ft roof, and you can use 75% of that roof area for solar panels, you can theoretically put 34 400-watt solar panels on a 1000 sq ft roof.
[PDF Version]
An 800w solar system could have a 1000w solar inverter and two 24v batteries of 200Ah capacity. This estimation is based on 5 peak sun hours, but this could vary widely depending on location and battery storage needed. Choosing the right inverter for your panels depends on multiple.
[PDF Version]
Let's walk through a complete example: Daily power usage: 2,000 Wh. With LiFePO₄ at 80% DoD: 200 Ah ÷ 0. You'd need at least a 12 V, 250 Ah battery bank.
[PDF Version]