Learn · Buying guides · 5 min
Why solar goes last: the sizing mistake that costs homeowners thousands
Solar companies size arrays against your last twelve utility bills. Sounds reasonable — until you realize those bills include every leak in your attic and every inefficiency in your twenty-year-old system. Size solar first and you're buying panels to power waste.
The arithmetic
Efficiency work routinely cuts a home's usage by a third or more. Do that first, and the array that covers your life shrinks by the same fraction — panels you never buy, racking you never install, roof you never fill. Efficiency dollars spent upstream delete solar dollars downstream.
When solar-first actually makes sense
- Almost never for a whole home — the sequencing math is stubborn.
- Occasionally for specific cases: new construction already built tight, or homes that have already done the envelope work.
- If a solar quote arrives without an efficiency conversation, that tells you whose interest the sizing served.