Solar payback calculator

Model payback with utility rate increases, EV vs gasoline savings, minimum monthly bills, and room to electrify later — not just a flat first-year savings number.

Your situation

Adjust assumptions to match quotes and your bill.

Electric utility

Roof direction

Solar system size6 kW

Installed cost3 $/W

Gross system cost

Defaults to $3.00/W × 6 kW. Replace with your quote.

Incentives / tax credit30%

Average monthly electricity use900 kWh

Solar production used at home60%

South-facing regional yield per kW1,100 kWh

Solar export credit

$/kWh

Monthly connection / customer charge

Estimate — adjust to match the fixed charges on your bill. Even at $0 usage, this usually remains.

Expected annual electricity rate increase3%

Current roof age12 years

Own or planning an EV?

Future electrification plans

Heat pump (space heating)Heat pump water heaterInduction stoveEV (if not modeled above)

Recommended size: 10 kW

Your current 6 kW model may under-cover planned electric loads (~0 extra kWh/year).

Estimated payback

8.8 yearswith 3% rate increases

Net cost after incentives: $12,600. Year-1 solar value: $1,276.

Payback, flat rates

9.9 years

With 3% inflation

8.8 years

Min monthly bill

$12

Cashflow snapshotAmount

Gross system cost$18,000

Incentives applied$5,400

Net system cost$12,600

Year-1 solar value$1,276

Year-10 value @ 3%$1,715

Zero-usage bill still costs about $12/month

Connection fees, taxes, and customer charges usually remain even when solar covers your kilowatt-hours.

Plan roof and solar together

A 12-year-old roof plus ~25-year panels often means one roof replacement during ownership. Budget panel remove/reinstall (commonly a few thousand dollars) or replace the roof before install when needed.

Solar alone does not power your home in an outage

Grid-tied panels shut down when the grid is down unless you add battery backup (and usually a transfer switch / hybrid inverter) designed for islanding.

Track real savings after install Annual solar value calculator

Planning assumptions

Not sure about baseline household kWh? Start with the electricity usage calculator. Payback compounds year-1 solar value at your chosen electricity inflation rate (import and export credits escalate together). EV uplift is gasoline avoided for home-charged miles minus the export credit those solar kilowatt-hours could have earned — a conservative framing. Fixed charges are not subtracted from solar value; they are shown so a “$0 usage” bill is not mistaken for a $0 bill. This is a planning estimate, not financial, tax, or contractor advice.

Why assumptions matter

Generic solar calculators often freeze electricity prices, ignore fixed utility charges, and leave out EV or future heat-pump load. Small changes in those assumptions meaningfully change whether solar looks like a 12-year or an 8-year decision.

Frequently asked questions

How do electricity rate increases affect solar payback?

Most calculators assume rates stay flat forever. When electricity prices rise, each kilowatt-hour your solar offsets becomes more valuable, which shortens payback. This calculator lets you model 0–6% annual increases and compares payback with and without inflation.

What is the minimum monthly bill with solar?

Even if solar covers your usage, utilities usually still charge connection fees, customer charges, and taxes. This calculator shows an estimated minimum monthly bill from those fixed charges so a zero-usage month is not mistaken for a $0 bill.

How does an EV change solar payback?

Charging an EV at home from solar can offset gasoline spending in addition to electricity. The calculator adds that incremental value (gasoline avoided minus export-credit opportunity cost) and shows how payback shortens. Estimate how much an EV adds to home use first with Gleam's electricity usage calculator.

Do solar panels work during a power outage?

Usually no. Standard grid-tied solar shuts down when the grid is down for safety. Powering part of your home during an outage generally requires a battery and equipment designed for backup.

Should I replace my roof before installing solar?

If your roof may need replacement during the panel lifetime, plan roof and solar together. Removing and reinstalling panels for a mid-life roof job can add thousands of dollars. This calculator flags that when roof age plus typical panel life suggests overlap.

Is this financial advice?

No. It is a planning estimate using editable assumptions for system cost, incentives, rates, inflation, and lifestyle. Confirm quotes, tariffs, tax treatment, and incentives with licensed professionals.