Net- Metering is a specific utility term used to describe the way utilities may allow small home generators to feed electricity back onto their electric distribution wire grids.
The DSIRE database, (Data base of State Incentives for Renewable & Efficiency) lists each state’s renewable programs. They define net- metering like this:
“Net Metering Rules For those consumers who have their own electricity generating units, net metering allows for the flow of electricity both to and from the customer through a single, bi-directional meter. With net metering, during times when the customer's generation exceeds his or her use, electricity from the customer to the utility offsets electricity consumed at another time. In effect, the customer is using the excess generation to offset electricity that would have been purchased at the retail rate. Under most state rules, residential, commercial, and industrial customers are eligible for net metering, but some states restrict eligibility to particular customer classes.”
This is a widely accepted definition but gets confused by some utility programs that don’t really offer net-metering. Instead they offer wholesale or avoided cost metering. This often requires two meters installed at the customer’s expense. One meter records the kWh flowing into their house from the utility grid and the other meter records the flow of electricity from the home’s power generation sources like a PV array or small wind turbine. The market drives the cost of electricity just like it does other commodities and the price we all pay on our electric bill reflects market value as well as actual costs for delivery. In the case of small alternate energy generators, utilities typically pay a wholesale rate for any energy that they buy directly.
One myth that is often used to oppose net-metering is the myth that meters go forward more accurately than they go backwards. Eletromechanical meters have no physical reason to run any differently more or less accurately no matter which way the current is going. Yet, this is the reason that many utilities require two meters. Two meters doubles your minimum monthly service charge and throws an un-necessary obstacle into the net-metering road.
Utilities that offer true net-metering, allow one meter that goes both directions. With this arrangement, consumer’s gain by having any energy that they generate going back to cancel the incoming kWh hours.
Once the meter hits zero on the register the price changes. Now you are making a net contribution to the grid instead of just canceling out your utility company generated power. So, the price you make on each kWh goes down to the wholesale rate which is typically 40 to 60 percent less than the retail rate. So, if you are going to run payback numbers for your project, you need to find out the average retail rate per kWh when you calculate the financial benefits of installing your own net-metering equipment.
Safety has always been very important to electric utilities and rightfully so. You can’t make any mistakes handling 14,000 volts of electricity without serious – usually fatal consequences. So, may utilities require a long list of lock out safety requirements and a hefty insurance liability policy from homeowners interested in installing net metering equipment.
Some utilities require a physical lock out device accessible to utility personnel; all day every day so that they can isolate your system from the grid while they are working on distribution circuits effected by your system.
I heard a good talk several years ago by a knowledgeable engineer about the potential danger from net-metering facilities. He seemed to think that the likely hood of a 12 or 24 volt 1.5 to 3.0KW net-metering system back feeding enough voltage to injury a line worker was a remote possibility and said it really was not scientifically supportable. Yet many utilities still persist in adding this substantial obstacle to net- metering installations from home owners.
Today, there are several alternate energy system inverters that take care of most of the legitimate interconnection and safety issues raised by utility regulations.
The main problem with net metering relates to the way you get billed for electricity. In most locations there are two parts to your bill. One part is a kWh charge that is supposed to cover all of the costs of getting each kWh to your house from the generation facility. The other part of your bill has a fixed minimum monthly charge or availability of service fee that is supposed to cover those expenses that a distribution utility incurs whether you use any electricity or not. If you leave town and throw your main breaker to the off position, you will not use any kWh. But, your meter is still sitting there ready for action and the wires coming to your house are still in the air or under the ground waiting for something to do and the utility company still needs to send a meter reader or use software to read your meter remotely just in case you use some juice that month. These fixed costs, like property taxes, accounting expenses and administrative expenses continue whether you use electricity or not. Also these expenses are often so high that utilities bundle a portion of the fixed expense into your kWh charge. So, if you are a net-metering customer whose meter hits zero or generates a lot of your own power that displaces the utility grid power , you are cutting into their revenue, without making a meaningful contribution to cutting the costs for buying power during the night and on cloudy days.
What may change utility attitudes toward net-metering is the growing need for additional generation resources and the clamor over fossil fuel generation. Utility executives maybe looking for net-metering resources to fill in peak daytime loads when the sun is shining, thus taking some of the pressure off financing new fossil fuel resources.
Do you have a question about how your electricity gets to your house? Ask me. I'll try to find out? GOt any other questions about electric energy generation? Ask me. I'll get some answers.
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