In our new series Landmark Solar Design, we will be exploring the world, all from the comfort of the Aurora office in Palo Alto. In each post, we will ‘travel’ to a famous landmark and investigate its potential for solar energy generation.
For each site, we will go through the entire solar design process - from determining an optimal component layout based on the roof structure and shading losses all the way to a cost analysis with various financial options.
With election season in full swing, we couldn’t think of a more appropriate site than the White House for the inaugural post of our series. We have prepared a preliminary site assessment and proposal for President Obama to look at in the last few months of his term (or the National Parks Service since they’re in charge of maintaining the White House grounds).
A brief history of solar energy at the White House
President Jimmy Carter on the unveiling of his solar thermal panels in 1979.
The White House is no stranger to the benefits of solar, and has had solar systems in place since 1979.
- 1979 - 32 solar thermal panels are installed on the roof of the White House by President Jimmy Carter. He predicted that solar could “be a small part of one of the greatest and most exciting adventures ever undertaken by the American people.”
- 1986 - Carter’s solar panels are dismantled by the Reagan administration.
- 2003 - Under the administration of Pres. George W. Bush, the National Park Service (NPS) oversaw the installation of a 10kW PV system, along with two thermal solar systems for the White House swimming pool.
- 2013 - President Barack Obama orders the installation of 6.3-kW of PV panels on the roof of the Obamas’ executive residence. The system is estimated to have an eight year payback period.
While 6.3-kW is a typical PV size for an average American home, the White House roof has untapped solar potential that could power administrative offices and facilities in the complex. The estimated yearly electricity consumption of the White House is around 852,500kWh, based on average kWh/sq ft of office buildings.
Given the size of the building, a commercial scale installation would be appropriate. To meet those electricity needs, we found more spots for solar panels on the roof of the White House.
Analyzing the roof structure
The White House has three main sections:
- Executive residences - where the Obama family lives
- West Wing - presidential offices
- East Wing - office spaces for the First Lady and her staff
And the two colonnades that connect the wings to the original central residence.
The grandiose three-story executive residence has various obstructions on the roof, making it difficult to place large arrays there in our solar design. Its height also results in shading on the surrounding structures.
The irradiance map reveals that the West Wing is a hotspot, not just for political activity but also for solar access.
Based on solar access values from nearby weather stations (TMY3), we see that East and West wings have the highest solar energy potential, followed by the unshaded regions of the East and West colonnades.
Solar system layout
Using Aurora’s autofill tool, we placed a total of 980 American-made SunPower solar modules on both wings and colonnades, for a 320-kW system. (For the colonnades, we only put solar modules where the annual solar access was more than 80%.)
|Row Spacing||2.0 ft|
|Number of Modules||980|
|Estimated Project Cost||$1,000,000|
Simulating energy performance
Taking into account system loss factors such as soiling, snow, and shading, our performance simulation engine estimates that the solar design can produce 358,123 kWh of electricity in a year.
The solar energy production would offset almost 43% of the White House’s electricity consumption, significantly reducing its carbon footprint.
Now, how should the United States government pay for the proposed solar system we designed?
Energy independence: Minimal shading across panels on the White House roof on the 4th of July
Cash If the White House paid for the entire system upfront, the payback period would be 11.65 years, or 2.91 presidential terms. Not ideal.
Loan Thankfully, the US government can get a pretty good deal with financing options. After all, federal infrastructure development isn’t quite complete without some healthy debt.
Let’s assume Uncle Sam takes out a loan consistent with its borrowing history. The loan covers 100% of the project cost and they don’t pay any dealer fees. The loan interest rate is benchmarked to the current 30 year treasury yield rates (USGG30YR:IND via Bloomberg).
That looks like a much better investment! Because we predict utility rate escalation at 3.5%, the deal only gets better as time goes on.
There you have it: Clean Energy Savings for All -- of the White House. It’s a sound business decision that would entice any candidate.
- We assume the cost is $3.25/W.
- We assume that the White House is on the Potomac Electric Company’s Residential Time Metered (RTM) schedule, with 3.5% utility escalation rate, and 5c/kWh for Net Surplus Compensation.
- We assume that the White House roof is structurally sound enough to support the weight of the solar generation system.