Introduction

Pre-Installation Forecast

Goal: Determine which, if any, of the solar quotes have a positive net present value based on historical usage data.

Usage Data (Apr 2019 to July 2022)

  • Usage per year (KWh): 15,286
  • Transmission Cost per year: $463.71
  • Distribution Cost per year: $631.15
  • Customer Cost per year: $120
  • Generation Cost per year: $1,205.15
  • Bill Total: $2,420.02

Options for Solar Systems

  • Blue Raven:
    • Panels: 32
    • W per panel: 400
    • Total Generation (KW): 12.8 = 32*400
    • Yearly (KWh): 13,380
    • Total Cost: $46,341
    • Tax Break: $12,049
    • Net Cost: $34,292
    • 25 yr Efficiency: 92%
  • EcoHouse
    • Panels: 39
    • W per panel: 360
    • Total Generation (KW): 14.04 = 39*360
    • Yearly (KWh): 15,453
    • Total Cost: $42,500
    • Tax Break: $12,750
    • Net Cost: $29,750
    • 25 yr Efficiency: 80%

Assumptions:

  • Energy Inflation: 4%
  • Overall Inflation: 2%

Forecast Timeseries

Calculate Forecasted 25 yr Net Present Value

  • Blue Raven: -$1,748.94
  • EcoHouse: $5,069.95

The Ecohouse solar options was selected

Pre-Installation Temperature vs Energy Forecast

Monthly Temperature Timeseries

Energy Usage vs Temperature

Energy Usage per Day vs Temperature

Energy usage per day should remove some variability due to months of different lengths

Regression Diagnositics and Fit

Actuals and Forecast (Post-Installation)

Actual Temp

Actual Usage since Installation

  • Total Demand - The amount of power used in the home
  • From Grid - The amount of power needed by the house from the grid
  • To Grid - The amount of power supplied by the solar panels to the grid
  • Solar Production - The amount of power created by the solar panels

\[Solar\ Production\ +\ From\ Grid = Actual\ Total\ Demand\ -\ To\ Grid\]

\[To\ Grid < 0\]

Comparison of Demand and Solar Production

Forecast Return on Investment

  • Break Even Year: 2036
  • 20 yr NPV in 2042: $11,302.74
  • 25 yr NPV in 2047: $19,286.09