MEMBERS-ONLY FACT SHEET
Non-Export Systems
Last Updated June 24, 2025
There are several reasons to configure solar and storage systems as non-export.
NEM add-ons: You can add a non-export system behind the same meter as a NEM-1 or NEM-2 system without losing the NEM status of the original system.
Public works law: AB 2143 requires prevailing wage and apprenticeships for all non-residential solar systems and for high-rise multifamily larger than 15 kW. However, this law does not apply to systems that do not use NEM/NBT. Systems installed under the Rule 21 non-export rules are not NBT.
Interconnection: You can install a non-export system in a location where grid capacity is insufficient for an exporting system.
The most common non-export approach is to use a certified power control system (PCS). A PCS can reduce the output of solar and storage in response to a power flow measurement. It can be contained within an inverter, battery controller, or hub. The PCS setting is established at installation.
In the basic PCS configuration with a single solar and storage system behind one meter, the measurement is at the service point. If a CT measures power flowing in the direction from the customer site to the grid, the PCS will shut down system production within two seconds. When power flows from the grid to the site, the system can produce power for onsite loads.
Until recently, the PCS standard was an optional component of UL 1741 known as a certification requirements decision (CRD). This has been converted to standalone PCS standard, UL 3141, which is being phased in to replace the UL 1741 CRD.
To find equipment with certified PCS:
Go to the CEC Approved Equipment List at https://www.energy.ca.gov/programs-and-topics/programs/solar-equipment-lists.
Under Grid Support Inverters, click on Power Control System List.
Click on Download Excel file on the right side.
The Import Only Mode column must be marked “Y”.
The Max Open Loop Response Time for Import Only Mode must be 2 seconds or less.
To design a non-export system:
Use equipment with certified PCS as detailed above.
Follow manufacturer instructions to set the PCS to Import Only Mode when you install it.
The reference point of the PCS must be the entire system rather than only the battery.[1]
Systems will require a CT or other measuring device at the service point. Follow manufacturers instructions.
The non-export options are contained in Screen I in Section G of Rule 21. Certified PCS is Option 8 in Screen I. It is also possible to use a non-export relay (Option 1). This can cost around $50,000 and is challenging to program correctly. Another option is to size the system no more than 25% of the site’s original service rating and 50% of the service transformer rating (Option 3) or no more than 50% of the customer’s minimum load over the past twelve months (Option 4). The other Screen I options are for inadvertent export or limited export. Those are not non-export.
Non-NEM/NBT systems have a higher interconnection application fee: $800 instead of the $90-$145 charged for NBT applications. Also, NEM/NBT contains exemptions from standby charges and departing load charges.
Customers with solar smaller than 1 MW are exempt from standby charges even if they do not participate in NEM/NBT. Non-NEM/NBT systems larger than 1 MW are subject to standby charges that can be large. See PG&E Schedule SB, SCE Schedule S and Schedule TOU-8-S, and SDG&E Schedule S.
Departing load charges are non-bypassable charges assessed on the amount of load that is served by self-generation. Solar customers not using NEM/NBT pay these charges. See PG&E Schedule DCG, SCE Schedule CGDL-CRS, and SDG&E Schedule CGDL-CRS.
NEM Add-Ons
NEM-1 and NEM-2 customers can add capacity without losing NEM status if the new capacity is managed separately as non-export. This involves different configurations from single-system installations.
In all of these configurations, the combined system must still be sized to onsite load, so the customer cannot have the old system effectively operating as a wholesale generator while the new system is taking care of all onsite consumption.
Configuration 1. Dynamic PCS
A power control system can be installed to ensure that the amount of energy exported from the site to the grid at any time is no more than what the legacy capacity is producing at that time. The PCS operating mode is certified to perform this way and the customer cannot switch to another operating mode, so verification is at commissioning without ongoing metering.
This function is slightly more advanced than the first version of PCS. With single systems, the power controls act in response to a single measurement at the meter. If power is flowing from the customer to the grid, the non-exporting devices must not be producing power. For hybrid systems, the legacy capacity can be exporting as long as the new capacity is not. Power controls on the new capacity act in response to measurements at both the meter and the output of the legacy system. If more power is flowing to the grid than is being produced by the legacy system, the new capacity must ramp down within two seconds.
The configuration cannot be used if the legacy system has storage set to Import Only/No Grid Exports.
The UL 1741 CRD does not test for this capability, but the capability has been incorporated into UL 3141. PG&E has sometimes been willing to approve equipment with this capability without certification. SCE and SDG&E has been requiring the UL 3141 certification.
This is likely the lowest cost configuration, but it may not be available with equipment you want to use until that equipment is listed or separately approved by the utilities.
SCE has released a guide on how to fill out an application using this configuration.
Configuration 2. New Meter [Discontinued, No Longer Available]
The utilities initially agreed to a configuration with a net generation output meter (NGOM) installed on the legacy capacity to verify that exports do not exceed production from the legacy system in real time. If the site is exporting more than the old system is producing, it must be coming from the new capacity, which is not allowed. Since this process has been rolled out, some customers have proposed systems with new capacity that freely exports, counting on the NGOM to clip export credits based on the production of the legacy system. Although the utilities initially agreed to this, they later realized that this approach violates the tariff, which states the new capacity must be designed as non-export. Since then, the utilities have withdrawn their initial approval of this approach.
The reversal in utility policy stranded customers who had already installed Configuration #2. CALSSA is still working on obtaining financial compensation or a tariff deviation for these stranded customers. No new applications, after the utilities changed their stance, are being accepted.
Configuration 3. New Subpanel
A new subpanel can be installed with new loads and/or moving old loads. The new solar and storage is installed on the new subpanel, and includes a PCS to ensure power is never flowing from the subpanel to the main service panel for more than two seconds. The new capacity feeds only the loads on the new subpanel. Power can flow from the grid to charge the new battery or feed the loads on the subpanel, but power cannot flow in the opposite direction. The new circuit is effectively load only from the utility perspective, although they are still requiring customers to submit interconnection applications.
This configuration requires the work and expense of installing a new subpanel, but it does not require UL 3141 certification. It would only require UL 1741 PCS CRD for Rule 21 Option 8 (max open loop response time < 2 seconds, time to steady state < 10 seconds).
[1] In a separate use case for installing solar plus storage that exports under NEM/NBT, a PCS can be installed on the battery only, with an open loop response time of 10 seconds. See CALSSA fact sheet on NEM/NBT Paired Storage.