ST. PAUL — Two versions of a bill mandating solar energy for big utilities are heading for a conference committee where compromise legislation should emerge in the final week of Minnesota’s legislative session.

The Senate version requires large utility companies to generate 1 percent of power from the sun by 2025. The House version requires 4 percent, in addition to the 25 percent renewable energy requirement passed in 2007.

Both bills exempt taconite operations, recycled iron ore mining operations and wood products plants from any rate increase attributed to the solar mandate.

The House bill also exempts rural electric cooperatives and municipal utilities. Together, it would exempt nearly a third of the state.