New Options for Adding Non-Export Solar to an Existing NEM System
The California Public Utilities Commission and the three major Investor-Owned Utilities recently approved new ways to add a “Non-Export” system to an existing NEM system. PG&E, Southern California Edison, and San Diego Gas & Electric now allow several methods that keep your current NEM status intact when adding new solar capacity. These changes create more flexibility for homeowners who want to increase on-site solar use without sending power to the grid.
Why System Expansion Usually Ends NEM
If you expand a NEM system by 10 percent or 1 kW, you lose your original NEM status. Utilities created this limit to allow simple maintenance, not system growth. Your NEM program determines how the utility credits your exported solar. Older NEM versions credit far better than newer ones. Your NEM agreement lasts 20 years from the date you received Permission to Operate. The newest tariff, called NBT, offers much lower export credits.
When Losing NEM Might Still Make Sense
In some situations, expanding your system and losing NEM may still help. You might benefit if your current system leaves you with high true-up bills and/or plan to increase electric usage. Many people add EVs or switch from gas to electric appliances. These changes can quickly outgrow your system’s original size. A detailed analysis helps determine whether expansion under NBT is worthwhile.
Adding a Non-Export System as an Alternative
You can also add a “Non-Export” system, which protects your existing NEM status. Utilities now allow several ways to meet non-export rules. Two methods use a Power Control System that manages power flow through software. Another method uses a separate utility meter called a Net Generation Output Meter, or NGOM. These options keep new solar from exporting to the grid.
Why Pairing Non-Export Solar With Storage Helps
Most homeowners gain more value by pairing a non-export system with energy storage. Batteries store excess solar instead of sending it to the grid. Storage also boosts resilience and reduces exposure to rising utility rates. Designing these systems requires careful analysis to maximize performance.
Adding Storage Alone Will Not Affect NEM
Adding only an energy storage system does not change your existing NEM status. You can install storage to gain backup power or extra savings without risking your current agreement.
Batteries on Wall
Drone Photo of Solar Panels on roof
How can you know if the company you’re working with is designing the new system properly? Can you be sure? Several companies say they can do it but not all do it properly is what I’ve been told….
Hello Nina,
It is a difficult system to design and does only makes sense in specific scenarios based on the recent true up, remainder of NEM grandfathering and future electrification plans. In addition to those considerations there are site specific things to consider with the where any expansion would be installed and if the electric system can take the expansion.