Have you ever wondered why your electricity meter may spin backwards after installing a PV system?  If you haven’t seen it before, a customer sent this video of his electric meter spinning backwards.



When the sun shines and your solar panels are generating more energy than you’re using, you “deposit” energy in the power grid, running your meter backwards.  At night, you withdraw – and any extra solar energy you don’t use is “rolled over” into your account at no cost.

At the end of the month, if you deposited more electricity than you used, you’ll receive a credit from the electric company.  If you used more than you deposited, you’ll receive a bill.  This is what is called Net Energy Metering (or NEM).

NEM allows you to offset all or part of your electricity bill from the electric company from the energy produced by your eligible renewable energy generation system.

According to Hawaii state law (Hawaii Revised Statues (HRS) Section 269-101 – 269-111), all residential and commercial utility customers who own and operate an eligible renewable energy generation system, up to a generating capacity of 100 kW, and intend to connect to the utility grid, must register their systems with their electric company by executing a NEM agreement. 

The executed agreement allows the NEM customer to connect their photovoltaic system to the utility grid, allowing it to export surplus electricity into the grid, and to receive credits at full retail value that can be used to offset electricity purchases over a 12-month period.

NEM customers are billed for net energy purchased, which is determined by subtracting the excess energy exported to the utility grid from the total energy supplied by the electric company. Here is the formula:

   Energy Supplied by the utility (kWh)  
-  Excess Energy exported to the utility (kWh)  
= Net Energy Billed to the Customer (kWh)

In Hawaii, eligible renewable energy sources are solar (photovoltaic), wind, biomass, or hydroelectric power or a hybrid system of two or more of these technologies, with a capacity up to 100 kW.

The Hawaiian Electric Company, Maui Electric Company, and Hawaii Electric Light Company support Net Energy Metering and recognize their roles to help Hawaii transition from fossil fuels to more renewable energy resources.