@AgAu thanks for that - no, I probably have, but haven't touched the 'controls' since it was installed - get the roof cleaner to hose down the solar cells from time to time. More serious attention is on my 'to-do' list this year. Mine cost around $3500 from memory - plus a few extras when the specialist electricians turned up.
I have to watch my money a bit - I am in the stockmarket only as a bad example to everyone else - haha !! lost lots in 2007-8 and haven't had the courage to re-enter big time since.
I watch and watch and think 'it's all just a big casino' - the trick is to get out while the going is good - I didn't.
I thought you might have installed your system yourself.
Thanks
Taurisk