The California Public Utilities Commission and the State’s three Investor-Owned Utilities (IOUs), PG&E, Southern California Edison and San Diego Gas & Electric recently approved some ways to add a “Non-Export” system to a previously approved NEM system.

First a little history. If you already have an approved solar system that is under the current net energy metering rules, just expanding the solar system by 10% or more or by 1 kW or more will lose the net energy metering (NEM) program your system is currently on. The NEM is what determines how you are credited to “spin your meter” backwards with your excess solar. Older versions of NEM credit better. The 10% or 1 kW limit was really designed for maintenance to allow for the replacement of a failed solar panel or two or inverter, not to expand a system. Your NEM status is good for 20 years from when the Permission To Operate (PTO) was first granted by the utility and the system could be turned on. The newest rendition of NEM is now called NBT for Net Billing Tariff. NBT credits are very small compared to NEM credits.

In some cases, it may still be a good idea to expand your system and lose your NEM status. For example, if your current system is not covering your electricity costs leaving you with a large annual true up bill, or if you plan to increase your electric usage, or if you were on a utility rate that was eliminated and your annual true up bill has increased. A conversation with a detailed analysis can determine if it’s a viable option. Many folks are adding an electric vehicle or moving from gas to electric for household appliances such as heating your home’s space, water, or for a stovetop, oven, or many other things. This can have a big impact on how well your system covers your electricity costs.

Another newly approved option that may be preferable is to add a “Non-Export” system. Adding a non-export system does not jeopardize the remaining NEM status of your existing system. There are a few approved ways to add a non-export system. Two of them use a newer technology called Power Control Systems (PCS) that uses software to control what the system is doing and meet the non-export guidelines required by your current NEM status. Another uses a separate utility meter called a Net Generation Output Meter or “NGOM”.

In most cases, it will be best to pair a non-export system with energy storage to maximize the benefit. These options also require a conversation, detailed analysis and a careful design, but may be a great way to cover more of your electricity costs and be more resilient from the ever-increasing utility rates.

It is very important to note that adding an energy storage system (ESS) alone to existing solar has no effect on the existing system’s NEM status. So you can add an ESS and enjoy the benefits of either additional savings or clean, quiet back up power with no loss to your current NEM agreement.

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