20 Free Energy Calculators: Solar, EV & Rate Tools

2026 Solar Savings Calculator: Payback at $0 Credit

14.6 years is the payback at 17¢/kWh on full-retail net metering with the federal credit at $0. Enter your rate, export rule and quote for your own number.

Average Electric Bill by House Size Calculator

935 kWh a month is the RECS 2020 average for a 1,500–1,999 sq ft home. Multiply by your state's current EIA rate for an honest estimate, by heating type.

Solar Lease vs Buy Calculator: Cash, Loan & PPA

Cash wins on lifetime dollars; a loan adds a 10–30% dealer fee; a lease keeps the 30% §48E credit with the lessor. Compare all three over 25 years.

Solar Tax Credit Eligibility Checker

$0 is the federal solar credit for any cash/loan purchase after Dec 31, 2025 — enter your dates and purchase type for your own §25D/§48E verdict.

How Much Do Christmas Lights Cost to Run? Electricity Calculator

About $1.14 for the whole season with five 100-bulb LED strings, $6.53 with incandescent, 6 hours a night for 32 nights at 17¢/kWh. Price your own display.

Generator Fuel Cost Calculator: Gas, Propane, Diesel per Hour

$3.24 an hour on gasoline at 0.75 gal/h and $4.32/gal (EIA weekly); propane $1.83, diesel $4.71. Your consumption, hours and days, plus a grid comparison.

What's Your Electricity Rate? Find It by ZIP Code

Type your ZIP, pick your utility from EIA's service-territory list and get its average residential price — every utility in all 50 states, labelled.

Why Is Your Electric Bill So High? Bill Jump Calculator

Weather, rate or usage: enter last month's and this month's bill and the tool splits the increase three ways, with EIA degree-days and your own rate.

Will Time-of-Use Pricing Cut Your Bill? Free Simulator

TOU beats a flat rate only below a break-even peak share. One tool for 15 large utilities' real tariff sheets: enter your kWh and peak share.

$2.04 a Day for a Space Heater: Electricity Cost Calculator

A 1,500 W space heater costs $2.04 a day over 8 hours at 17¢/kWh: watts ÷ 1,000 × hours × rate. Price any appliance by hour, day and year from 16 presets.

EV vs Gas: What Do You Really Save Driving Electric?

4.6¢ a mile electric vs 13.6¢ on gas at 17¢/kWh and $4.07 a gallon. Enter your miles, rate and mpg for your yearly saving; the federal EV credit is $0.

Tesla Supercharger vs Home Charging: Cost Compared

Home charging runs 4.6–5.8¢ a mile at 17¢/kWh; a Supercharger price is yours to enter from the app. Compare per mile, per 100 miles and per year.

EV on a Time-of-Use Rate: The Whole-Home Net Calculator

Off-peak charging can save on the car and cost on the house: the net whole-home result on verified TOU tariffs, from your kWh, rates and charging window.

What Size Heat Pump Do You Need? Free Sizing Estimator

About 20 Btu per sq ft (Efficiency Maine's published method): 2,000 sq ft brackets to 32,000–40,000 Btu/h. A zone-adjusted range, cited, no Manual J.

What Temperature Should You Switch Off Your Heat Pump?

At EIA's outlook prices a heat pump needs COP 3.73 to beat a 95% gas furnace, above most units' 17°F rating. Find your crossover from named NEEP units.

Is Your Heat Pump Working Right? Free Performance Check

Inside its NEEP envelope or not: enter before-and-after monthly kWh and the month's weather to see whether your heat pump's real draw matches its rating.

Heat Pump vs Furnace Cost Calculator 2026: Yearly Savings

Usually cheaper than propane, oil or resistance heat, rarely cheaper than gas at 95% AFUE: yearly heating cost, heat pump vs furnace, from your prices.

What Outdoor Temp Should Your Dual-Fuel System Switch?

Switch where heat pump and furnace cost the same per MMBtu; the point moves with your gas and electricity prices. Find yours from NEEP COP curves.

Home Battery Payback: Buy vs Third-Party-Owned Calculator (2026)

A bought battery gets $0 federal credit in 2026; a third-party-owned one carries the 30% §48E. See the year buying overtakes, from your own prices.

Home Battery Payback: Who Still Gets the 30% Credit?

Only a third-party-owned battery still reaches the 30% §48E credit; one you buy gets $0 in 2026. Model payback both ways from your backup needs and prices.

How Many Solar Panels Do I Need? Calculator for Any US State

6–10 kW (15–25 panels) offsets most US homes. Enter your bill or kWh, pick your state to adjust production and rate, and get size, panels and roof area.

Should You Go Solar in 2026? 4-Question Reality Check

Buy, lease, community solar or wait: a four-question verdict for 2026 with the federal credit at $0, built on your rate, export rule and how long you stay.