ok so im trying to work out

If i got a 1.5kw system, how much money does it save or make in a quarter??

Origin are offering me a 299 up front cost and 100 bucks a month over 2 years to own the system.

Im trying to work out if its worth me doing it, will the system save me 300 a quarter off my power bill to warrant purchasing it. Or will i loss out for the first 2 years then start to see a saving?

Sorry im new to all this