I went to Kibtek last week to find out exactly what the rules are....
If you want to "cash in" your excess kW credit on your account, they will give you 0.25TL per kW.
I was advised it is not worth doing this and better to just leave it on your account so that it can be used at a later date.
Previously I was told that in March they re-set the credit, ie: you will lose any credit on your account that has not been used or refunded.
Apparently this was the case initially but not now, I was assured the credit will stay on your account.
My advice to anyone with a lot of solar generated credit on their account, use airconditioners to heat during the winter months, it has saved me buying the normal 1,300TL of diesel for my heating system. Will also save on purchases of wood for wood burners.
Thank you to the team at the Kibtek Office in Girne, they were all very helpful
