How to Read Your Electric Bill Before Going Solar

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Short answer: Pull twelve months of kilowatt-hours, the price of each one, every fixed or minimum charge, and the rule for electricity you send to the grid. Those figures, not the dollar total on a single bill, are the right starting point for a solar estimate. A quote that ignores the season, the rate structure or export credits can look tidy and still misstate the bill. This page shows where the numbers sit, how net metering differs from net billing, and how to carry them into a calculator.

In this guide

Work through the bill in this order.

• The five numbers that matter
• Monthly and annual kilowatt-hours
• Flat, tiered and time-of-use rates
• Fixed charges and minimum bills
• How export credits change the maths
• A hypothetical worked example
• Checklist before you request quotes
• FAQ

The five numbers that matter

Before array size, take five items from the bill or the online account.

1. Kilowatt-hours for each of the last twelve months, and the annual total.
2. The energy price in cents per kWh: flat, tiered, or by time of day. If supply and delivery are separate, note both.
3. Fixed charges, including any customer charge and any minimum bill that applies when usage is low.
4. The rate plan name, and whether solar customers must switch plan.
5. The export rule: retail net metering, a separate export credit, or another method, plus when credits expire or reach a true-up.

This month's amount due is only the result of those inputs. A mild month, a rate change or a one-off credit will not describe the year. The U.S. Department of Energy's homeowner guide to going solar tells readers to grasp their own use, and the way the utility bills, before they compare offers.

Monthly and annual kilowatt-hours

Energy on the bill is in kilowatt-hours. One kWh is one kilowatt running for one hour. Proposals quote capacity in kilowatts, often as DC nameplate. A 7 kW array is not 7 kWh of production. Yearly output depends on location, tilt, direction, shade, equipment and weather. That yield is a model estimate, not a bill figure.

Find the usage line, often labelled kWh used or total energy. If supply and delivery are unbundled, do not add the two usage figures. They usually describe the same energy, and they should match.

A single month is a poor stand-in for the year. Air conditioning, electric heat, a pool, an EV or guests can move usage by hundreds of kWh. The Energy Information Administration's FAQ on household electricity use gives a national average. That average is revised when new data are published, and it will not match every house. Check it for context, then design from your own history.

Collect twelve consecutive months from the utility portal or from paper bills. Note each month, the highest, the lowest and the annual total. The month-by-month list shows whether that total is steady or driven by a season.

Add a margin note for loads the history misses. A planned EV, heat pump or extension is not inside last year's kWh. A large appliance you have already stopped using means the history is too high.

If the bill multiplies a kW demand figure by a price, copy that line separately. Residential demand charges are uncommon, but where they exist a midday array does little for a short peak after dark.

Flat, tiered and time-of-use rates

The price per kWh may be one figure or a table.

A flat rate prices every kWh the same, with fixed fees alongside. Annual energy cost is roughly annual kWh times that rate. Make sure delivery, riders and taxes are inside the rate or added once, not both.

Tiered (inclining block) rates use a lower price up to an allowance and a higher price above it. The allowance may reset monthly and may change by season. Solar tends to remove the dearest kWh first, so an average cents figure misleads. Copy each threshold and price, and note kWh per tier for a high month and a low month.

Time-of-use rates follow the clock. If the bill shows kWh in each period, copy them. If it shows only dollars, look for hourly data in the portal. On many home plans the costly hours are late afternoon and evening, when rooftop output is falling, and cheaper hours are overnight. Midday solar may be off-peak or mid-priced. Do not let a quote value every solar kWh at the peak price.

Some tariffs combine tiers with time bands, or change prices by season. Note the dates. Dividing the amount due by kWh is only a cross-check: it hides the structure and, if you start from the grand total, mixes fixed charges into the energy price.

EIA state electricity profiles show why a single national price will not match your bill. Use them as context only.

Fixed charges and minimum bills

Solar cuts purchased kWh. It does not, on its own, erase charges that ignore how much you use.

Look for a customer charge, basic service charge or meter charge. If you remain connected, that fee usually stays. The amount is set locally. Do not reuse a figure from another utility.

Then look for a minimum bill: language that raises the bill to a stated floor when energy charges fall below it. Under a rule like that, a very sunny month can still produce a bill. Put the floor into any savings sketch unless your tariff clearly waives it for solar customers. The right number is the one in the tariff, not a guess.

Some taxes and riders are charged per kWh and shrink as imports shrink. Others are flat. Read the label on each line. If the bill summary is unclear, open the tariff sheet the utility publishes.

A grid-tied system without a battery still imports after sunset and exports near noon, so a bill remains. A zero-bill promise usually means fixed charges were ignored.

How export credits change the maths

The export rule is where two quotes for the same roof diverge.

Where traditional net metering is still open to new customers, exports are often credited near the retail rate, commonly as kWh carried forward. A true-up may later pay leftovers at a lower rate or clear them. In that pattern, annual production times your retail energy rate is a fair first sketch, if fixed charges remain and surplus credits are not valued at full retail forever. Price the programme a new system would actually join, not a neighbour's older agreement.

Net billing prices imports and exports differently. You pay retail for power you take, and you receive a separate credit for power you send, often a lower one. Full retail value applies only to solar the house uses while the panels are producing. Everything exported is worth the credit alone. A battery can shift surplus towards the evening, but it also adds cost. The solar plus battery guide sets out that trade-off. A low export price does not, by itself, prove storage will pay.

California is the clearest large case of net billing. The California Public Utilities Commission net billing tariff, for the big investor-owned utilities, compensates exports with avoided-cost values that change by the hour, rather than a one-for-one retail swap. Those values are updated, so none are quoted here. If you are on one of those utilities, read the Commission page and your current tariff, and insist each quote states its export assumption. If you are elsewhere, do not copy California, and do not assume your state still credits exports at full retail. The proposal should name the tariff.

On the same page of the rules, note whether credits expire, whether they offset delivery as well as supply, and whether imported kWh still carry non-bypassable charges. The production total in a proposal is still an estimate, shifted by shade, dirt, snow and downtime.

A hypothetical worked example

All figures in this section are hypothetical. They are not your bill, not a quote and not a promise of savings.

Assume the household has logged a full year. Annual use is 11,400 kWh. April is the low month at 620 kWh, and August is the high month at 1,350 kWh. The energy rate is a flat 18 cents per kWh, taken here as already including supply and delivery. The customer charge is 12 dollars a month. There are no tiers, no time-of-use prices, no demand charge and no minimum bill in this illustration.

Energy for the year, 11,400 kWh at 18 cents, comes to 2,052 dollars. Fixed charges, 12 dollars times 12 months, come to 144 dollars. The illustrated annual bill is 2,196 dollars.

A proposal in this story estimates 9,000 kWh of production. That yield is invented.

Case A: full retail credit

Suppose retail net metering credits all 9,000 kWh at 18 cents and no surplus is left at true-up. Energy still bought is 2,400 kWh, or 432 dollars. The customer charge stays 144 dollars, so the illustrated bill is 576 dollars. The illustrated reduction is 1,620 dollars. What that reduction means for payback depends on installed cost and incentives, which the payback guide and the solar cost guide explain. Do not treat 1,620 dollars as your result.

Case B: a lower export credit

Keep 9,000 kWh, but assume 40 per cent is used on site (3,600 kWh) and 60 per cent is exported (5,400 kWh). Imports still cost 18 cents. Exports are credited at 6 cents. Both the split and the 6 cents are made-up inputs.

On-site use avoids 648 dollars (3,600 kWh at 18 cents). Export credits add 324 dollars (5,400 kWh at 6 cents). The illustrated benefit is 972 dollars, not 1,620. Imports left are 7,800 kWh (11,400 minus 3,600), or 1,404 dollars, minus 324 dollars of credit, which leaves 1,080 dollars, plus 144 dollars fixed. The illustrated bill is 1,224 dollars.

Same production guess, different export rule, much smaller change in the bill. If August's 1,350 kWh falls mostly in the evening, on-site use can sit below 40 per cent. April, at 620 kWh, may export heavily, so the true-up rule decides what those spring exports are worth. An annual total hides both months.

Checklist before you request quotes

Before you ask for quotes, finish this reading list.

1. Gather twelve consecutive months of kWh, not only the latest bill.
2. Flag a move, a vacancy, a new EV, a failed heater or any other one-off month.
3. Write down the annual total, the highest month and the lowest month.
4. Record the rate plan name and any solar plan you would be switched to.
5. Copy every energy price: flat, tiered or time-of-use, and both seasons if they differ.
6. Note whether supply and delivery are split, so your rate is not half the story.
7. List fixed monthly charges and any minimum bill.
8. Mark which other lines shrink with kWh and which stay.
9. Write the export rule: net metering or net billing, expiry, true-up and non-bypassable charges.
10. If a kW demand charge appears, keep it separate from kWh.
11. List equipment you plan to add or remove.
12. Then put your kWh and your own rates into a solar savings calculator, and keep the monthly pattern beside it.

Hand that sheet to anyone quoting. They should state the import rate, the export rate, assumed on-site use, and that fixed charges stayed in. Otherwise two proposals cannot be compared. If you want installer prices, you can request quotes through Powur. Check every quote against this list before you sign.

FAQ

Is twelve months really necessary?

Yes. A mild month hides cooling or heating, and a peak month inflates the year. Use twelve months, and mark any month distorted by a move, a vacancy or equipment that will not stay.

Will solar wipe out the electric bill?

Not on a typical grid-tied system. Customer charges and any minimum bill usually remain, and you still buy electricity when the panels are not covering the load. Export credits can be worth less than the retail rate.

How should I read a time-of-use bill?

Copy kWh and price for each period, not a single blended average. On many plans the high price is late afternoon and evening, after rooftop output has dropped. Do not accept a quote that values all solar kWh at the peak rate.

What is different about California exports?

For the large investor-owned utilities, the CPUC net billing tariff pays exports on hourly avoided-cost values, not as a retail kWh swap. The values change. Use the Commission page and your current tariff, not a cents figure remembered from an article. Other states write their own rules.

Why not start from the amount due?

Dollars mix energy, fixed fees, taxes and occasional credits. Two households with the same amount due can use very different amounts of electricity. Start from kWh and the rate table, then check that the dollars roughly agree.

Sources

• U.S. Department of Energy: homeowner's guide to going solar
• U.S. Energy Information Administration: how much electricity does an American home use?
• U.S. Energy Information Administration: state electricity profiles
• California Public Utilities Commission: net billing tariff