NV Energy is asking state energy regulators to change the formula of how it bills customers in Southern Nevada — a change the utility says would give customers more decision-making power around energy efficiency, but that accountability groups argue would be confusing and expensive for customers.

NV Energy is proposing to raise its flat rate for service across Northern Nevada while lowering how much customers pay for actual energy use — a move watchdog groups say penalizes customers with low incomes or those who curb their power usage through conservation or by adding rooftop solar installations.