The rising number of solar rooftop installations is creating concerns that too much energy is flooding into the electricity grid, and could cause blackouts as the system struggles to control the excess power.

"Solar spill", when high levels of energy are generated by rooftop installations in the middle of the day when demand is low, is becoming a problem for Australia’s electricity networks, according to Andrew Dillon, the head of the grid representative body Energy Networks Australia.

The rise of rooftop solar is a boon for households but creating a headache for electricity distributors. Credit:Michele Mossop

"If this goes badly, one of three things is going to happen," he said at an Energy Networks 2018 event on Wednesday.

"Either we get voltage and frequency issues at the local level or even localised blackouts and things tripping off."