1. Your monthly bill ÷ the NJ average retail rate ($0.18/kWh) gives us your annual electricity usage.
2. We size a system that produces about 95% of that usage using New Jersey's typical specific yield (roughly 1,250 kWh/kWp/year for a south-facing, unshaded roof), derated for orientation and shading.
3. System cost is estimated at $2.85/watt before the 30% federal tax credit.
4. SREC-II / SuSI income assumes the current residential-tier clearing price of about $85/MWh, paid for 15 years.
5. 25-year cumulative savings compound your year-1 bill savings at 3.5% annual utility rate escalation and add the 15 years of SREC income.

This is intentionally conservative. Real proposals from our design team run PVsyst or Helioscope production modeling, use your actual utility history, and reflect your exact roof geometry.