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Plan it · Check it · Track it

The honest math
for your roof.

Installers sell residential solar on 25-year promises built from optimistic assumptions. We run the numbers independently — your roof simulated hour by hour, outcomes bracketed from bad luck to good luck on rates and panel aging, against everything else your money could be doing instead. No installer affiliations. No lead-gen.

Start free forecast Audit my proposal · $19no signup to start · address + utility bill
Sample household · Boulder CO · 7.2 kW
25-year cumulative net wealth
likely range · P10–P90
Median NPV
$31,400
today's dollars · 5% discount
Crossover yr
yr 9
solar > grid $/kWh
P10 outcome
$8,200
if utility rates stall
Payback (today's $)
11.2 yr
installer claimed 7
vs savings acct 4.5%
$12,900
same cash, parked in the bank
P90 outcome
$58,700
if rates climb like history
── one engine, three questions ──
8760
hours in a year — we simulate every one, for all 25 years
P10–P90
the span between a bad-luck outcome and a good-luck one, across weather, rates, and panel aging
0%
affiliate revenue · lead-gen handoffs · referral fees
NEM 3
California's post-2023 solar export rules, priced hour by hour