March 12, 2018
Video Resource: Excel tutorial on calculating payments on a $26,000 auto loan
In-Lab Assignment: Construct an Excel spreadsheet for financing the purchase of a $150,000 home using a 30-year mortgage of monthly payments and a fixed interest rate of 4% and answer the following questions:
- How much total interest will you be paying on this mortgage?
- Suppose you make one extra payment per year on the principal of the loan, spread out over the year (e.g., if your monthly payment is $600, recalculate your worksheet with a payment of an additional $50/month). What happens to the total interest paid and the number of months before the mortgage is paid off?
- Suppose instead that after 10 years of dutifully paying your mortgage, interest rates fall to 2%. The bank will let you refinance the remaining 20 years on your mortgage at the lower rate, but you must pay a fee (a.k.a. “closing costs”) of $1,000. Should you refinance your mortgage? Justify your answer carefully and completely with the appropriate calculations.
March 5, 2018
Tour of the Share-Swenson-Watson (SSW) building
February 26, 2018
NREL System Advisor Model (SAM)
In this lab your will perform a full system and financial analysis of a residential solar installation. You will need the following.
1. Location of your home (or the property for which you are doing this analysis) – GPS coordinates preferred (use Google Earth)
2. Approximate angle of the roof
3. Compass orientation of the roof
4. A typical electric bill with 12 months of power consumption
Before lab review this tutorial for SAM
5. You should also be prepared to estimate the interest rate for any debt financing of the system and an estimate for the annual increase in the price of power.
6. Run the full SAM simulation on your project. Modify the model to test the range of reasonable assumptions for interest rates and electricity pricing.
7. Export the results of each run as a CSV file and import the date into Excel. Define the meaning of each row in the simulation and track the calculations. Build a new calculated row to calculate the total cash flow of the project as a function of year.
8. Tabulate the results from each simulation paying attentions to the output functions: Nominal LCOE, Net present value, Internal Rate of Return, and Payback period. Define each of these terms. Calculate the Net Present Value and Internal Rate of Return in Excel using the modeled payments for life of the solar system.
9. Now considering the results of your analysis, why wouldn’t every electricity customer consider solar?
Resources
Google’s Project Sunroof
National Renewable Energy Lab: System Advisor Model
GBS-pricing-schedule
Post Tariff PV pricing
Reports & Analyses
Professor King’s home:
– Solar Electric Proposal (Garage Roof 18 Renesola 255w)
– Solar Shade Analysis
– King PV system analysis.zsam
Professor Donihue’s home:
– Solar Shade Analysis
– Solar Electric Roof Project
– SAM analysis for roof project (Model file; Excel download)
– Solar Electric Tracking Proposal
– Solar Domestic Hot Water Proposal
– Electricity bill for January 2018
February 19, 2018
Heat of Wood Combustion Calculations Worksheet
Calculating the heat content of fuels 2018
Bonds Broken Bonds Formed Worksheet
February 12, 2018
Biomass Plant Tour
Simple payback calculations worksheet for Colby’s Biomass Plant – Test your understanding.