Real Time Solar

Solar maths that is actually correct in 2026

The 30% federal solar tax credit ended on 31 December 2025. Most calculators online still apply it, so their payback periods are years too optimistic. These do not.

Work out your payback

What changed

The 30% federal residential solar credit (Section 25D) ended for expenditures after 31 December 2025. Homeowners buying in 2026 receive no federal credit. Businesses are treated differently under Section 48E.

Where solar still pays back fastest

Payback is driven by your electricity rate far more than your sunshine. These are the five quickest and five slowest states on an 8 kW system.

Fastest

Slowest

Why the rate matters more than the sunshine

Massachusetts gets roughly 4.2 peak sun hours a day and pays about 30 cents a kilowatt-hour. Florida gets 5.2 hours and pays about 15. The Florida system produces around 24% more electricity — but each unit is worth half as much, so the Massachusetts system pays back roughly five years sooner.

If you are working out whether solar makes sense where you live, look at your bill before you look at the sky.

The calculators

Every state