Pakistan, Feb. 11 -- The last couple of years have seen ordinary Pakistanis turning to the sun for relief, when amid prolonged summer power cuts and skyrocketing electricity bills, rooftop solar panels offered a lifeline-a way to keep the lights on and costs down when the national grid faltered. That lifeline is now under threat.

In a startling policy shift, the National Electric Power Regulatory Authority (NEPRA) has officially ended the one-for-one net metering arrangement, making sure that every unit of electricity from the grid will be billed at full price, while every unit sent back to the grid from a rooftop panel will earn only a fraction in return.

There are already nearly half a million Pakistani households and businesses feedi...