Modelled savings and metered savings are different claims. One is a projection built from irradiance data; the other is what the discom actually billed. For this house we have both, for twelve consecutive months, and the gap between them is small enough to be worth publishing.
The system is 5 kW on an east-west split roof in Sector 78, Noida, commissioned in April 2025 with a hybrid inverter and no battery. The household ran four air conditioners through the summer and did not change its consumption behaviour after the install, which makes the comparison cleaner than most.
7,140
Units generated in twelve months
₹68,400
Reduction against the prior year's bills
1.9%
Variance from the modelled estimate
Where the savings came from
Roughly two-thirds of the reduction is direct self-consumption: units produced and used inside the house at the moment of generation, which never reach the meter. The remaining third is export credit, banked under net metering during the long generation days of March through June and drawn down in the monsoon.
The bill has a floor
Fixed charges, meter rent and taxes continue regardless of generation. A well-sized residential system takes the variable portion close to zero; it does not take the invoice to zero, and any quote promising that is describing something else.
What the monsoon costs
July and August are the honest months. Generation fell to about 60% of the April peak across those two billing cycles, and the household drew from the grid on eleven days in the period. Banked credits absorbed most of it. Without them the monsoon quarter bill would have been closer to ₹9,000.
Sizing for the sunniest month makes a good brochure. Sizing for the year is what keeps the bill flat in August.
This is why we model on twelve-month generation rather than on peak-day output, and why we size against your annual consumption instead of your worst bill. Over-sizing for July gives you surplus you cannot bank indefinitely; under-sizing for April leaves you paying grid rates in the months the system should be carrying you.
What to take away
Neha Rastogi
Energy analyst
Builds the savings models behind every RePrime quote, using meter data from commissioned systems rather than brochure yields.
Run these numbers against your own bill
The calculator uses state-wise generation data and the current subsidy slabs. Two inputs, one estimate, no call required.
