Normally, VA (Volt* Ampere) is the same as W (Watt) (= capacity) in direct current. This is the case with solar panels.
Now if you want to change from Watt (Capacity) to kWh (consumption), you must estimate how many hours of energy solar panels will generate (= full-load hours). Here, we make an estimate of approximately 900 hours per year, the same estimate that VITO (Flemish Institute for Technological Research) makes.
A system of 5kW will therefore produce 5*900 = approximately 4500 kWh of electricity.