Installing Tesla solar panels in a house costs $18,000. It is expected that the average monthly savings will be 1,000 kWh per month. Assuming that the utility company charges 0.2 per $/kWhr.

1. What is the Present worth of this investment for i=6% and N=15 years?
2. A different approach could be to install energy efficient windows and enhance the insulation for $12,000, which would yield average monthly savings of 700 kWh per month. Assuming the same interest rate and time span. What is the present worth of this alternative?
3. Which option would you choose? Why?