Transmission and Distribution loss (T&D) and Aggregate Technical and Commercial (AT&C) loss are both crucial metrics used to assess the health of the power sector.

Not considering challenges due to poor interface and consumer metering, there are significant variations in loss estimates depending on the methodology used for calculating losses.

The estimation methodologies used in many states do not consider energy as handled by the system, especially to account for the following recent trends:

• Energy required to meet open access and off-site captive demand
• Treatment of sale to  consumers in distribution franchisee areas
• Energy input in the inter-state transmission network as well as the distribution network due to renewable energy generators, net metered consumers, etc.

Using a spread-sheet based tool, developed by Prayas, Energy Group called Calculating Loss and Energy Accounting in Regulatory practice (CLEAR), this paper, by comparing methodologies shows that there could potentially be a variation in losses calculated up to 4 percentage points.

Such stark variations call for a disaggregated and standardised approach to estimating T&D losses. Only then will efforts such as fixing trajectories for loss reduction in the regulatory process, comparing performance of DISCOMs across years and across states, and charting the progress of programmes like UDAY and IPDS that use these metrics be meaningful.

The report and the calculator can be downloaded from the links given below.

CLEAR works best with Microsoft Excel 2010 and above.