Clear answer, explained.
There is no single solar-offset percentage that is ideal for every commercial solar project.
The appropriate target depends on how much electricity the facility consumes, when it consumes it, how much usable roof or land is available, the capacity of the existing electrical infrastructure, utility interconnection constraints and the economics of increasing the system size.
For some facilities, a high annual offset can produce a very strong return. For others, reaching the final portion of electricity consumption may require less productive roof areas, electrical upgrades, additional interconnection work or substantially more capital. In those situations, a smaller system may provide better capital efficiency.
The objective should therefore not be to maximize the percentage for its own sake. The right solar-offset target is the one that creates the strongest overall business case while remaining technically appropriate for the facility.
What this means in practice.
- There is no universal ideal solar-offset percentage for a commercial building.
- Higher electricity offset does not automatically mean better project economics.
- The facility's annual consumption and load profile establish the electricity opportunity.
- Usable roof or land, electrical infrastructure and interconnection capacity establish practical constraints.
- The incremental cost of increasing system size should be compared with the additional electricity savings it creates.
- The optimal target should come from technical and financial modelling rather than an arbitrary percentage.
Best-fit environments.
- You are comparing several commercial solar system sizes.
- You want to know whether targeting 100% electricity offset makes financial sense.
- Your facility has enough roof area to install more solar than may be economically necessary.
- You are reviewing solar as a capital investment and comparing return across different system sizes.
- Management wants to understand why the largest possible system is not automatically the strongest investment.
