THE SHORT ANSWER
OUC’s current TruNet FAQ says an add-on solar PV system will not affect a grandfathered account’s status and will be billed under the same rate plan as the original installation. The add-on is still a new scope that must follow applicable requirements. [1]
Confirm the account classification
Ask OUC to verify that the electric account is actually grandfathered and keep the response. Panel age, a seller’s statement or a credit on one bill does not establish the account category. This article reports the utility’s published policy; it is not an account-specific rate determination.
Define what “add-on” includes
List the new module count, inverter changes, storage and total post-project system rating. An expansion may involve more than attaching panels. Ask whether the existing inverter, service equipment, roof space and monitoring platform can support the proposed design.
Review the combined electrical system
The utility and permitting authority need a coherent final system, not separate old and new sales sheets. Request a one-line showing existing and added equipment. Recalculate the applicable tier and identify any insurance, disconnect or transformer questions for the combined capacity.
Keep ownership permissions visible
If the original system is leased, financed or covered by a service agreement, obtain any required authorization before another contractor changes it. OUC rate treatment does not give permission to modify equipment owned by someone else or establish how a warranty will respond.
Model the incremental value
Compare the expansion cost with the additional production and how your current OUC account treats that energy. Use recent household consumption, not the original system’s sales estimate. Origin Direct can review an expansion proposal while OUC confirms the rate and application treatment.
Before your next conversation
- Get OUC confirmation of the current account category.
- Calculate the combined system size and tier.
- Obtain equipment-owner approval before modifications.
Primary sources
- OUC: Rooftop Solar and TruNet FAQs
Primary reference checked September 9, 2026. Confirm current requirements with the named utility, manufacturer or authority for your property.
Planning examples and questions are Origin’s editorial guidance, not a property-specific diagnosis, engineering design, tax determination or promise of savings. Manufacturer and utility references do not imply an affiliation with Origin.
Make the decision specific to your home.
Bring the existing system record and new layout to an Origin Direct expansion review.
Book an Origin Direct review →Scope, pricing and availability are confirmed for your property. A consultation does not establish utility or incentive approval.