I've got a 5kw system with 22 panels and it saves us heaps even in winter when we are using heaters flat out our bill is heaps less than what we were paying we are saving 300 to 400 a bill every 2 months so its definently worth it.It cost $8500 all up and it was on 3 years interest free and will pay for itself in 3.5 years how can you go wrong?