Chapter 9 · Installation Process
9.2 Step 1: usage analysis and system design
- Collect the last 12 months of utility bills (PG&E, SCE, SDG&E, CenterPoint, TXU, PSEG, etc.).
- Look at monthly kWh and TOU period distribution.
- Anticipate next-5-year consumption changes (EV? heat pump? ADU?).
- Size the array: winter monthly production ≥ winter monthly consumption × 1.5.
- Size the battery: enough to cover the 4-hour evening peak + one full night of base load.
- If your EV can charge during the day, the battery does not need to be as large.
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9.1 Step 0: assess the roof's remaining life
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9.3 Step 2: contract review (7 must-check items)
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Questions after reading this section? Send us your utility bill — we will come back within one business day with a recommendation specific to your situation.