Monthly netting compares the energy a solar plant generates with the energy the facility consumes as a total at the end of the month: whether the generation occurred in the morning or at midday does not enter the calculation. The move to hourly netting removes this assumption. What now decides the outcome is whether generation and consumption overlap in the same hour; this fundamentally changes the self-consumption calculation and the value of the solar surplus.
Why timing starts to matter
In a typical industrial facility, consumption is relatively even through the day, while solar generation is a bell curve peaking at midday. Under monthly netting the shape of these two curves did not matter — only their areas (total energy) were compared. Under hourly netting, the area where the two curves overlap defines actual self-consumption, and the non-overlapping midday peak defines the surplus that has to be dealt with.
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The netted share falls at the same facility
With the same generation and consumption data, the netting method changes how self-consumption is reflected in the accounts: physical generation and consumption stay the same; what changes is the netted (valued) share. The comparison below shows this on a representative profile: under the monthly method the ratio looks high because the timing difference is hidden; under the hourly method the midday surplus separates out and the actual instantaneous self-consumption emerges.
| Netting method | Apparent self-consumption | Status of the midday surplus |
|---|---|---|
| Monthly | ~85% | Timing difference invisible |
| Hourly | ~60% | Treated separately |
Where the strategy shifts
When the midday surplus no longer earns its value by itself, two technical options come to the fore. The first is load shifting: aligning flexible processes with the generation peak to enlarge the overlap area. The second is storage: taking the midday surplus into a battery and using it at the evening peak — which ties the solar-surplus storage scenario directly to BESS feasibility. Which one makes sense depends on how flexible the facility's load profile is and how large the surplus is; both should be modeled on the same 15-minute data.
What to check before deciding
Before deciding on a solar plant or solar + storage under hourly netting, three things should be settled: the hourly overlap profile of generation and consumption, the distribution of the midday surplus across the year, and the real shiftability limit of the flexible loads. A self-consumption estimate made without measuring these three remains nothing more than monthly logic carried into an hourly world.