I recently "inherited" a 4.5 kw inverter (heavy duty!) which had been bought and then not used for 10 years - the person who had it never got around to putting their system in place. I connected it into my system and although it hummed and made other encouraging noises, no power came out

I pulled it apart but it looked to be in pristine condition, even after 10 years in storage. So after some false starts, I found someone to look at it for me - good news was I had not stuffed up the installation, bad news was it would cost me $300 to fix

It appears that the inverter had been stuffed from the very beginning, but because it had never been tested in a system, no-one new. Obviously any warranty period is well expired.
Moral of story - if you buy equipment now for installation later, check to see that it is working before consigning it to the storage area!
Hopefull I will pick it up today - fun on the weekend

Nev
(Note: inverters change 12v DC to 240v AC)