Clear answer, explained.
Annual electricity consumption is an important starting point, but it does not show when a facility uses electricity. A detailed analysis therefore begins with interval consumption data, which records electricity use throughout the day and reveals operating patterns, seasonal changes and peak-demand periods.
The financial model also needs the facility’s utility bills, rate class and applicable tariff structure. These determine how purchased electricity is billed and which charges can realistically be affected by onsite generation.
On the generation side, the proposed solar system requires a site-specific production model based on factors such as usable roof area, orientation, shading, local solar conditions and system design. The expected generation profile is then compared with the facility’s load profile to determine when solar electricity can be used onsite and how much grid electricity is likely to be displaced.
Future changes should also be considered. New production equipment, facility expansion, electrification or EV charging can materially change the consumption profile used to size a system. Where the facility has broader efficiency opportunities, a commercial energy audit can help establish the appropriate consumption baseline before the commercial solar system is sized.
What this means in practice.
- Annual kWh alone is not enough for detailed solar modelling.
- At least 12 months of consumption history helps capture seasonal operating patterns.
- Interval data shows when electricity is actually being consumed.
- Utility rate class and tariff information determine how avoided grid purchases should be valued.
- Solar production should be modelled for the specific site rather than using generic annual output assumptions.
- Planned changes to facility load should be incorporated before final system sizing.
Best-fit environments.
- You are preparing a commercial solar feasibility study.
- You want a project-specific savings estimate rather than an industry-average calculation.
- Your facility has seasonal, multi-shift or variable operating patterns.
- Your electricity consumption is expected to change because of new equipment, expansion or electrification.
- You are deciding whether efficiency measures should be considered before final solar sizing.
