Been in residential solar for a while now, and the #1 thing homeowners get wrong is comparing quotes by total price instead of price-per-watt and payback period.

Here's the quick framework we walk every homeowner through:

1. Price per watt, not total cost. A $25k system and a $18k system aren't comparable unless you know the system size (kW). Divide total price by system wattage. Anything in the $2.50-$3.50/watt range (post-incentive) is competitive in most US markets right now.

2. Payback period matters more than sticker price. A slightly pricier system with better panel efficiency can pay back faster if your roof has partial shade or a smaller usable area.

3. The 30% federal tax credit is dollar-for-dollar, not a deduction. A lot of homeowners don't realize this drops effective cost dramatically — always ask installers to show pre- AND post-incentive pricing separately.

4. Get your usage in kWh, not just your bill total. Utility rates vary, so a $200/month bill means very different things in different states. Installers sizing a system off bill amount alone are guessing.

If you're mid-way through getting quotes, run them through this filter before signing anything. Happy to answer questions here if anyone's stuck comparing offers.