Tesla has recently announced a new version of solar shingles. These shingles are becoming increasingly competitive due to larger size (and therefore less labor for installation) and continuously increasing efficiency. You need to replace a 3,000 square foot roof and are considering the solar shingle approach. To fully maximize the solar shingle roof you also desire installation of two Tesla powerwalls, which will store energy generated by your solar shingles to provide "off grid" power.

The cost breakdown of Tesla's solar shingle estimate (including tax rebates/incentives) is below:

-Solar shingles with installation: $37,180

-Powerwalls with installation: $17,000

The new system will generate on average 40kWh per day and your home consumes 30kWh per day. Net metering is in place requiring the utility to buy back any excess power that you generate. The average rate per kWh purchased in Michigan is $.143 and the net metering rebate is assumed to be the same at this time. Energy is estimated to increase at a rate of 3.5% annually.

Should you choose to go forward with a traditional roof, this would cost you approximately $16,000 including materials and installation.

1.) Based on the information above, how long will it take you to pay off your investment based on the provided costs and energy savings?

2.) What is the impact on your payback timing if the State of Michigan removes net metering from the equation, meaning that the utility will not be compelled to buy back your excess power generated?

3.) If this roof is estimated to last 30 years, what is the present value of the investment (assume no net metering exists for your calculation)?

4.) If you chose to purchase the standard roof and put the balance of your money into US Treasury Bills at 2.38% what is the difference in present value compared to the solar roof option?

5.) Based on your answers to #3 and #4, would you proceed with the solar roof looking exclusively at financials provided above?