How to Read Your Electricity Bill Before Going Solar

Why your bill is the starting point

Before you ask anyone for a solar quotation, take out your electricity bill. A sensible solar proposal begins with how much power you use, when you use it and what you pay for it. Without those facts, any capacity or savings figure is a guess. Many buyers also size a system from the total payable on one bill, which includes charges that solar does not change.

A bill from the Uttar Pradesh DISCOMs, such as PVVNL, MVVNL, PuVVNL, DVVNL or KESCO depending on your area, carries a lot of information in a small space. Layouts change between bills and over the years, so this guide describes the common items in general terms. If your bill differs, look for the equivalent line or ask the sub-division office to explain it.

This article is general information and not tariff advice. Rates, slabs and surcharges are decided by the regulator and can change, so check the current tariff order or your DISCOM's website for exact figures.

Units consumed (kWh)

The most important number is the energy you used in the billing period, shown in kilowatt-hours (kWh) and commonly called units. One unit is one kilowatt running for one hour: a 1,000 watt heater for an hour, or ten 100 watt bulbs for an hour. The bill usually shows the opening reading, the closing reading and the difference between them.

Solar system size starts from units, not rupees. As a rough planning guide, one kilowatt of rooftop solar in Uttar Pradesh produces somewhere around 4 to 5 units a day on average across the year, which is about 120 to 150 units a month. Production varies by season, shade and cleanliness. If your average use is 300 units a month, a system of roughly 2 to 2.5 kW may cover most of it, subject to roof space and a site survey.

Check whether your bill is based on an actual meter reading or an estimate. Estimated or average billing can hide your real pattern. If your readings are often estimated, take your own photographs of the meter at the same date every month.

Sanctioned load and contract demand

Sanctioned load is the maximum power, in kilowatts, that your connection is approved for. It appears on the bill, usually near your account details. It is not the same as what you actually use. Under net metering rules, the solar capacity you may connect is generally linked to your sanctioned load, so a small sanctioned load can limit system size.

If you plan to add a new air conditioner, a pump or an electric vehicle charger, your load may need to rise. A load enhancement is a separate request to the DISCOM, with its own fee and paperwork. Find out early, because it can affect both the solar system and your fixed charges. Ask your installer to check your sanctioned load against the planned system, and to mention the rule that applies.

Commercial and industrial connections may have contract demand in kVA, billed under different rules. If you are a business, read our article on solar for shops and small offices.

Tariff category and slabs

Your tariff category, such as domestic or commercial, decides the rate per unit. Domestic tariffs are commonly set in slabs, which means the rate per unit rises as consumption crosses certain limits within the billing period. Some categories also have different rates for rural and urban supply, and for metered and unmetered connections.

Slabs matter for solar because generated units usually replace your most expensive units first. If your use is high, the units you stop buying are the ones in the top slab, which can save more per unit than your average rate suggests. If your use is already low and sits in the lowest slab, solar saves less per unit. Look at your bill's slab breakdown and ask the installer to calculate savings using it.

The figures below are only an example to show how slabs work. They are not actual Uttar Pradesh tariffs. Use your own bill and the current tariff order for real numbers.

Fixed charges, duty and other items

Besides the charge for units, a bill carries fixed charges linked to your sanctioned load, electricity duty, and in some cases surcharges, adjustments or meter rent. These do not fall to zero when your solar system generates units. This is the main reason a household with solar may still receive a small bill each month, even when generation is equal to or above consumption.

Ask your installer to show an expected post-solar bill with the fixed charges included. Someone who promises a zero bill without mentioning fixed charges is either oversimplifying or leaving something out. Our guide on how net metering credits appear on your bill shows what the remaining bill typically contains.

Arrears or a previous balance can also appear on the bill. Clear these before applying for net metering, as unpaid dues can delay approval.

• Fixed or demand charges: based on sanctioned load, usually charged every month.
• Electricity duty and taxes: calculated on the energy and other charges as per current rules.
• Surcharges and adjustments: fuel and power purchase cost adjustments may appear and change over time.
• Previous dues and late fees: clear them before applying for net metering.

Collect twelve months of bills

A single bill shows one month, and that month may be unusual. Summers with several air conditioners can use two or three times the units of a mild winter month. A shop may have wedding-season peaks. A home with children away at college may have uneven months. Twelve bills show the whole pattern and let you size the system on the annual average and the seasonal swing.

If you do not have paper copies, you can usually download previous bills from your DISCOM's website or app using your account number, or ask the sub-division office for a statement. Write the units for each month in a simple table.

Turning your bill into a rough solar size

Once you have your annual average units per month, divide by roughly 120 to 150 units per kW per month to get a starting capacity. For example, 360 units a month divided by 135 gives about 2.7 kW. Round to what fits your roof and budget, and consider whether you want to cover your whole bill or only part of it.

This is a first estimate. Real generation depends on shade, tilt, direction, dust, temperature and system losses. Government subsidy rules cap the capacity supported and the amount that applies by size. For current subsidy details, see our PM Surya Ghar guide and the official portal.

You can also try the calculator on our home page. It shows its assumptions, and its figures are estimates. Rely on a written proposal made after a site visit.

Common bill-reading mistakes to avoid

A few errors lead buyers to the wrong system size or unrealistic savings expectations.

• Sizing from the amount payable on one bill instead of the annual units.
• Ignoring sanctioned load, then finding the DISCOM will not approve the planned capacity.
• Expecting a zero bill and forgetting fixed charges and duty.
• Using a summer bill as the average, which leads to an oversized system.
• Not checking whether the bill is based on actual readings or estimates.
• Planning to add heavy loads later without allowing for them in the system size.