Billing DG backup fairly: why grid and DG should be metered separately
Diesel generator backup is one of the most expensive services a society provides, and one of the most argued about. Fuel, maintenance and operator costs make every DG unit far costlier than a grid unit — so how that cost is shared matters.
The common approaches, and their problems
- Equal share or share by flat area. Easy to calculate, but a flat that was locked during a power cut pays the same as one running three air conditioners.
- Folding DG into maintenance. Hides the cost entirely, so nobody has a reason to use DG power carefully.
- Estimating from total DG hours. Better, but still an estimate — and estimates invite challenge.
Metering by source
With dual-source metering, each flat's meter records consumption separately depending on whether supply is coming from the grid or from DG. Each source is charged at its own rate. A resident who used 0.8 units on DG during last night's outage pays the DG rate for exactly 0.8 units — no more, no less.
This does three useful things:
- It makes DG billing accurate, which removes the main source of disputes.
- It makes the cost visible, which encourages residents to go easy on heavy loads during outages and can extend DG capacity.
- It gives the committee source-wise reports to reconcile DG running costs against what was recovered.
Setting the DG rate
The DG rate should reflect the society's actual cost of generation — fuel plus a reasonable share of maintenance and operation. Many committees review it quarterly as diesel prices move. Whatever method is used, publishing how the rate was arrived at goes a long way towards acceptance.