Sunday, October 25, 2015

Renewable energy Net Metering billing explained

I installed the first phase of my solar power system back in the summer of 2009 with the help of many friends and neighbors.  Once the system was commissioned and approved by my utility, I signed a Net Metering Agreement with them.  This contractual agreement stipulates that they give me full retail credit for every kilowatt hour of energy that I export from my property back into the grid.  Originally, I had a traditional old-style analog meter and this meter would simply turn backwards on a sunny day before they came out and installed a second meter as part of the Agreement.  From this point forward my bill indicates readings from both meters.  One meter indicates how much energy I have imported from the grid, and the other indicates how much energy I exported.  I am billed (or credited) for the NET difference.
My electric meters
In the image above, the top meter shows that I have imported 22476 kWh and exported 11017 kWh since these meters were installed in April 2011.  Essentially I have offset 50% of my energy over six years using solar power.  Since the system has grown over time that percentage is currently higher.  For instance, over the last 12 months I exported 3383 kWh, imported 5222 kWh with a net usage of only 1983 kWh

In the summer months I export more than I import and thanks to the Net Metering Agreement, the utility gives me a full retail credit for every kilowatt hour exported and this credit is carried forward.  They do not pay me directly but simply apply this credit to subsequent bills until such time as I use it up.  They do not carry a credit forward if it has run over 12 months.  I have had a very good year this year and have not paid my utility for electricity since May (it is now mid-October) and I am still carrying a credit that will apply to my next electric bill.  Here is the section of my bill indicating the most recent meter readings:
Section of my electric bill showing imported and exported energy.
Not long after commissioning my system, I installed a TED 5000 real-time energy monitor in my circuit breaker box.  This feeds information to a web page that I can view on my local network.  This helpful tool allows me to view energy consumption in great detail in various charts showing energy consumption by the second/hour/day/month.  Below is a screenshot showing monthly energy flow for the last couple of years:

Chart updated in July 2016
 Blue indicates energy imported yellow  indicates solar energy produced and  green  indicates the net energy per month.  I had a net energy surplus for 3 months each summer.

In a larger context, I am considered a micro generator that contributes power to the grid.  By doing this, I am reducing the load on the local grid which actually does the utility a favor.  However, the utilities do not see it this way due to the lost revenue and many utilities are beginning to fight back to prevent them having to give credit or payouts to people that provide renewable energy into the grid.  This is shortsighted thinking and they are going to have to adjust their business model as more renewable energy systems are brought online.


  1. The utilities in my area of Texas only credit incoming power at wholesale and charge retail when you use it again. You are lucky to live in a relatively progressive part of the country.

  2. rj if I was lucky I'd live in Germany where they have a Feed In Tariff law that pays WAY more than retail for exported power. Now that's an incentive! Tried to get that law passed here in Maine with no luck.


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