Solar Calculator

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  • Purchase (cash): Customer owns the PV system from day one, pays upfront with cash
  • Purchase (loan): Customer owns the PV sysytem starting Day 1. It is purchased with a loan, sometimes with a down-payment and paid back at a fixed interest rate
  • Lease, 15-year buyout: Install company or developer owns the PV System. Customer pays a fixed monthly payment that is adjusted for inflation. At 15 years, the customer elects to purchase the system and assumes full ownership.
  • Lease, extension: Same as “Lease, 15-year buyout” except that in Year 15 the customer elects to extend the lease with the leasing company

We assumed a $4 cost per watt, along with the 30% federal ITC. Note that utility data is based on residential rates from EIA-861 forms, so some electric utilities’ rates might be out of date. Also note that insolation rates by zip code were gleaned from U.S. National Renewable Energy Laboratory data.

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