Google’s Project Sunroof

Curious to know what an investment in solar looks like?

Google’s Project Sunroof – an online solar estimator – can give you an estimate of the cost to install a system and years until payback. Estimates provided by Google’s Project Sunroof are based on current electric rates. Future changes in rates will impact the estimated net savings and payback. Project Sunroof is not functional for all of Idaho Power’s service area, so we’ve provided three Project Sunroof examples of a typical home below.

Note: On Oct. 11, 2019, Idaho Power and the Staff of the Idaho Public Utilities Commission (IPUC) filed a settlement agreement with the IPUC requesting changes to the compensation structure for residential and small general service customers with on-site generation. Learn more about this case on the IPUC website.

Examples for using solar on-site generation to match nearly 100% of a home’s energy use
illustration of a small houseThe Jones’ House illustration of a medium sized houseThe Zhang’s House illustration of a large sized houseThe Jackson’s House
Average monthly electric use: 500 kWh 1,000 kWh 1,950 kWh
Average monthly bill:  $45  $90  $175
Solar system size needed:  3.75 kW  8 kW  15.75 kW
Estimated upfront cost:  $13,300 ($3.55 per watt)  $26,700 ($3.33 per watt)  $51,000 ($3.23 per watt)
Net cost after tax credit:  $8,400  $16,700  $31,900
Purchasing with a loan
 Estimated breakeven point:  Beyond 20 years Beyond 20 years Beyond 20 years
Total savings after 20 years (Simple Savings):  -$6,300 (loss)  -$9,900 (loss)  -$15,000 (loss)
Total savings after 20 years (Net Present Value):  -$4,200 (loss)  -$6,500 (loss)  -$9,700 (loss)
*Average monthly bill costs are based on Idaho Power residential Schedule 01 rates as of Nov. 1, 2018. System production estimates are from PVWatts default system settings for Boise ID. All other estimates regarding cost and payback are from Google’s Project Sunroof, which are based on current electric rates. Future changes in rates will impact the estimated net savings and payback. Project Sunroof uses a 20-year loan term and 6.6 percent interest rate. Actual costs, system production and tax credits will vary. For a personalized estimate, Idaho Power recommends getting several bids from certified installers.

1Why does Project Sunroof provide two different 20-year values?

Simple savings, or the payback method, and net present value are different ways of looking at the long-term value of a purchase. Payback tells you how long it takes to recoup your money. Net present value determines if it is a good financial investment compared to other things you could do with your money—like earning interest in your bank account or investing in stocks and bonds.