Certainty's coming for solar power users in Auckland.

Vector - which owns the city's power lines - is announcing details of a new solar energy package today.

The company is also guaranteeing a buy-back rate of 16 cents per kilowatt hour until the end of January 2016.

It'll do this by topping up the retailer's buy-back rate to 16 cents.

Vector says this will give potential solar customers more certainty, before investing in the technology.