Guides
Reading your electricity bill before buying solar
Find three figures: units consumed per month across a full year, the tariff slab you fall into, and your sanctioned load. Units drive system size, the slab decides how much each generated unit saves you, and sanctioned load determines whether net metering will be approved.
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Units across twelve months, not one
Consumption swings enormously between a Punjabi July and a January, so a single bill tells you almost nothing. Write down the units for twelve consecutive months and total them. That annual figure is what a system should be sized against — a system sized from a peak summer bill is oversized for most of the year and never pays back the difference.
The slab is why two neighbours save differently
Domestic tariffs here are banded, and the top band costs substantially more per unit than the bottom. Solar removes units from the top of your bill first, so a household deep in a high band saves more per generated unit than one near the bottom with an identical array. This is the single most overlooked variable in payback arithmetic.
Sanctioned load, and why it stops applications
Your bill states the load sanctioned on the connection. Net metering approval expects a sensible relationship between that and the system you install, and a mismatch is a common reason a file is returned. Check it before ordering equipment — revising a sanctioned load after installation is slower and more irritating than getting it right first.
The parts solar will not touch
Fixed charges, meter rent, taxes and levies do not scale with the units you save, so no rooftop system takes a bill to zero. Separate those lines from the energy charge before estimating savings, or the projection will overstate what solar can do and you will feel misled by your own arithmetic.
How do I read my electricity bill to plan for solar?
Which figure on the bill actually matters most?
Units consumed, totalled across twelve months. Everything else — slab, payback, system size — is derived from it. Rupees billed is the wrong figure to work from because tariffs change during the year, so a rupee total blends consumption with rate changes and hides which one moved.
My bill is high in summer and low in winter. What do I size for?
The annual total, adjusted for how much you can actually use during daylight. Sizing for the July peak leaves you with panels producing units you cannot use for eight months of the year, and without net metering those units are simply lost. Sizing to the annual figure is the standard approach for a reason.
Where do I find the sanctioned load?
It is printed on the bill, usually near the connection and tariff details, in kilowatts. If you cannot find it, the distribution company can confirm it against your reference number. It is worth knowing before you get quotes, because it constrains what can be approved regardless of what a salesperson proposes.