Homes with solar installations receive special meters called “net meters” that are certified for accuracy when spinning both forwards and backwards recording both the power used from the utility and the surplus generation delivered back to the utility. 

What Is a Net Meter and Why Do I Need One?
Most customers have a simple electric meter that is designed to measure the flow of electricity only from GWP to the customer. To receive the full benefit of your solar system, you need a “net meter” that is designed to spin both forwards and backwards accurately. This is important in solar installations because during high producing times of the day the system may generate more than the home needs, sending excess energy back to the utility.

How Does a Net Energy Meter Work?
When the solar system is operating during the day, it is possible to have times during the day when the solar system produces more energy than the home is using. When this happens the excess energy generated automatically goes through the net electric meter into GWP's distribution grid, running the meter backwards to credit your account. At other times of the day, your electric use may be higher than the solar system is producing, and you must rely on additional power from GWP. This forward and backward spinning of the meter is instantaneous as power needs change and will not affect the quality of the electric power supplied. 

How Does GWP Net Meter?
GWP’s net energy metering rules and processes are generally in line with net metering throughout California. Once the Interconnection Agreement is approved, a service order to install a net meter on the home is issued.  Following the net meter installation, the Utilities Billing department updates your account to reflect the location as being on a Net Energy Metering rate, or "NEM". This is a special billing arrangement that provides value to you if you have an active solar PV system at your home or business.  Under NEM, your electric net meter keeps track of the “net difference” between the electricity you consume and the electricity you deliver to GWP within each billing period.

Once the system is installed, monitoring the energy production will be your means of verifying the solar system is operating properly. Ask your solar contractor what monitoring system comes standard with your solar system, what monitoring upgrade options are available and if there are any costs involved.

Monitoring is used to track and optimize energy production and to reduce long term operational and maintenance costs. Solar system monitoring is available in a multitude of ways. A simple way of monitoring, if you have a string inverter, is to look at the LCD screen and record the information you see on the LCD screen. Other providers may supply a display device to be located in your home or in your garage. And still others may provide an on-line portal to view near real-time energy production graphs. Investigate what is being offered with your system and the options you have available. 

At a minimum, monthly monitoring is recommended. More often is better.  With monthly monitoring, a system problem or lower than expected energy production may be identified, investigated and fixed providing you with the anticipated rate of return on your investment. 

At the end of the year, pull out your solar system contract. Note the estimated annual energy production for your installed system and if there is a performance guarantee. Compare the estimated annual energy production to the actual production obtained from the inverter or monitoring device.  Is your solar system performing as anticipated?  If not, contact your solar contractor and ask them to investigate. 

Solar System Maintenance
Solar systems are low maintenance requiring occasional cleaning, electrical system checks and inverter preventive maintenance checks. Having your system inspected every year or two is recommended. Ask your solar professional for guidance on maintaining your system.

Dirty solar panels are the most common maintenance issue and can significantly reduce the energy production of the solar system. Dust, leaves, twigs, bird waste and soot on or under the solar panels can have a negative effect on the system. Keeping the array clean will boost energy production. 

Shading on any portions of the solar array will reduce energy production.  Shading of the system was considered by the contractor when your system was designed, and the energy production estimate included existing shading issues. Over time shading on the system may change – trees grow and other obstacles that create shade may occur. Routinely check for shading and investigate if there is an unexpected drop in energy production.

Loose wiring connections, cracked panels or other physical problems with the system may occasionally occur. System maintenance inspections should be performed to ensure safe and reliable operation. 

 

All equipment must carry a 10 year warranty. A solar module has an estimated life of 20 or more years. The solar inverter typically has a shorter estimated life and often is the system component to fail first. Proper care and maintenance of the inverter will help extend its useful life. 

Ask the installing contractor about a maintenance contract – talk about cleaning above and below modules, checking all mechanical and electrical connections and wiring, inspection of air ducts and cooling fans and checking expected energy production to actual.