The Green Party wants to invest millions to help about 500 schools install solar panels and sell the power they make.
Co-leader Russel Norman said on Thursday that schools' electricity bills were too high and they would be able to save $41 million over the 25-year lifespan of solar panels if they were installed.
The party would invest $20 million over three years to kick-start solar panel use in schools.
Dr Norman said the Greens would need to determine the level of demand, and if it was higher than that the party would accommodate it if possible.
Schools would be able to sell power they don't use back into grid to make money during holidays and weekends and the size of a school would help determine how much is given to instal the panels.
Grants would be overseen by the Education Ministry under the Greens' policy.